Co-reporter:Aoli Wu, Fei Lu, Panpan Sun, Xuanxuan Qiao, Xinpei Gao, and Liqiang Zheng
Langmuir December 12, 2017 Volume 33(Issue 49) pp:13982-13982
Publication Date(Web):November 20, 2017
DOI:10.1021/acs.langmuir.7b03504
Supramolecular ionogels were prepared by self-assembly of small molecules through host–guest interaction between β-cyclodextrin (β-CD) and a room-temperature ionic liquid (IL) 3-(1-methyl-3-imidazolio)propanesulfonate-lithium bis(trifluoromethanesulfonyl)imide (MIPS-LiTFSI) which contains zwitterion MIPS. 19F NMR and 2D ROESY 1H NMR have been used to prove that only TFSI– is involved in the complexation. 1H NMR, FT-IR, and comparative tests indicated that the electrostatic interaction between imidazole cation and TFSI– anion and intermolecular hydrogen bonding between three compounds also contribute to the formation of supramolecular ionogel. Ionogels with different gel–sol phase transition temperatures can be obtained by adjusting the molar ratio between β-CD and MIPS-LiTFSI. In addition, the supramolecular ionogels composed of “channel type” structural β-CD have been constructed. The ionogel with high conductivity and low activation energy open a door to new fields for special applications.
Co-reporter:Na Sun, Xinpei Gao, Aoli Wu, Fei Lu, Liqiang Zheng
Journal of Molecular Liquids 2017 Volume 248(Volume 248) pp:
Publication Date(Web):1 December 2017
DOI:10.1016/j.molliq.2017.10.121
•Mechanically strong polyzwitterionic ionogels were prepared without any crosslinker.•The mechanical performance is even comparable to chemically crosslinked ionogels reported.•The zwitterionic groups play an important role in the excellent mechanical property.•These polyzwitterionic ionogels also show satisfactory self-healing property and comparable electrochemical property.Recently, ionogels have obtained widespread attention as excellent functional materials due to their advantageous properties, such as nonvolatility, nonflammability, and good electrochemical properties. Herein, a novel two-component ionogel system exhibiting superior mechanical strength and flexibility, satisfactory self-healing property, as well as comparable electrochemical property is constructed through in situ photopolymerization. This kind of ionogels is free of any crosslinker and comprised of a polymerized imidazolium-type zwitterionic salt as polymer backbone and an ionic liquid 1-butyl-3-methylimidazolium chloride (bromide) as solvent. The zwitterionic groups interact strongly with each other and the ions of ionic liquid solvent, resulting in the formation of the physical crosslinking within the polymer chains and the ion-dipole interaction between the zwitterionic group in the polymer backbone and ionic liquid solvent which endow the ionogel with superior mechanical strength without any crosslinker. The compression strength and tensile strength can reach 58 MPa and 2.3 MPa, respectively. The mechanical performance of these polyzwitterion ionogels is even comparable to chemically crosslinked high strength ionogels reported. These tough ionogels also show good self-healing properties at their glass transition temperature and have 80% recovery of their original strength. Moreover, these ionogels exhibit comparable ionic conductivities and can be well-maintained even after successive bending or folding.Download high-res image (232KB)Download full-size image
Co-reporter:Panpan Sun;Fei Lu;Aoli Wu;Lijuan Shi
Soft Matter (2005-Present) 2017 vol. 13(Issue 13) pp:2543-2548
Publication Date(Web):2017/03/29
DOI:10.1039/C7SM00304H
Wormlike micelles were successfully fabricated by the self-assembly of a single-tailed zwitterionic surface-active ionic liquid (SAIL), 3-(1-hexadecyl-3-imidazolio) propanesulfonate β-naphthalene sulfonate (C16IPS-Nsa), in aqueous solutions without any additives. With increasing zwitterionic SAIL concentration, spontaneous transition from micelles to wormlike micelles and then a hexagonal phase occurs. Interestingly, the wormlike micelles are closed, stretched and directionally arranged, which was rarely found in previous research studies. This kind of wormlike micelle is useful to serve as novel soft template in the synthesis of functional materials. 1H NMR illustrated that the introduced π–π stacking and hydrophobic interactions originated from the hydrophobic aromatic counterions are responsible for the structural transformation. Density functional theory (DFT) simulated the optimum configuration of C16IPS-Nsa and calculated the interaction energy of C16IPS-Nsa–H2O is 39.6 kJ mol−1. This work paves the way for regulating the self-assembly structures of amphiphiles through changing specific weak interactions.
Co-reporter:Yizhi Liu;Xinpei Gao;Fei Lu;Mei Hu;Lijuan Shi
Soft Matter (2005-Present) 2017 vol. 13(Issue 17) pp:3072-3075
Publication Date(Web):2017/05/03
DOI:10.1039/C7SM00414A
Through the formation of dynamic covalent bonds, we succeeded, for the first time, in achieving a reversible chiral transfer from amino acids to perylene bisimide aggregates in aqueous solutions. Two opposite helical aggregations are induced with L-phenylalanine and L-tyrosine, respectively. It is possible that the change in configurations of phenyl groups in amino acids leads to the chiral inversion of BAPBI arrangements.
Co-reporter:Yizhi Liu;Xinpei Gao;Mingwei Zhao;Fei Lu
New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 15) pp:7643-7649
Publication Date(Web):2017/07/24
DOI:10.1039/C7NJ01107E
Herein, supramolecular gels from L-aspartic acid-based perylenebisimides (APBI) and various isomeric benzene dicarboxylic acids (o-phthalic acid, OPA; isophthalic acid, IPA and terephthalic acid, TPA) were obtained. It has been found that spatial position of carboxyl on the benzene ring plays a key role in the gelation process, and OPA or IPA could lead to gel formation while TPA could not. Intermolecular hydrogen bonding and π–π stacking interactions have been found to guide the aggregation as determined by UV-vis spectra, fluorescence spectra and FT-IR. Moreover the chirality transfer from perylene chromophores to benzene dicarboxylic acids was detected via circular dichroism spectroscopy (CD). The interesting features of the two-component gel system may give a better understanding of supramolecular chirality.
Co-reporter:Xinpei Gao;Fei Lu;Yizhi Liu;Na Sun
Chemical Communications 2017 vol. 53(Issue 4) pp:767-770
Publication Date(Web):2017/01/05
DOI:10.1039/C6CC08730B
The co-organization of polymerizable imidazolium-based ionic liquids and p-xylene led to the formation of a bicontinuous cubic phase with a primitive-type periodic minimal surface, and for the first time an anion exchange membrane preserving 3D interconnected ionic nano-channels was fabricated through in-phase photopolymerization of bicontinuous cubic liquid crystals.
Co-reporter:Xinpei Gao, Fei Lu, Bin Dong, Aoli Wu, Na Sun and Liqiang Zheng
Journal of Materials Chemistry A 2016 vol. 4(Issue 34) pp:13316-13323
Publication Date(Web):29 Jul 2016
DOI:10.1039/C6TA05223A
In this study, we present a facile method to construct highly ordered and well-defined ionic channels in anion-exchange membranes (AEMs) through in-phase photopolymerization of liquid crystals (LCs). Hexagonal and lamellar LC samples were prepared by the self-organization of polymerizable amphiphilic imidazolium-based ionic liquids. The preservation of LC nanostructures in the obtained polymeric membranes was confirmed by the combination of small-angle X-ray scattering (SAXS), polarized optical microscope (POM), and scanning electronic microscopy (SEM) measurements. Phase separations of LCs at the molecular level provided highly ordered and well-defined ionic channels for efficient anion conduction and meanwhile maintained a strong hydrophobic domain to suppress the swelling degree. The membranes synthesized in the present work provide a promising model system for understanding the idea of constructing ionic highways in AEMs through self-organization.
Co-reporter:Tao Zhou, Xinpei Gao, Bin Dong, Na Sun and Liqiang Zheng
Journal of Materials Chemistry A 2016 vol. 4(Issue 3) pp:1112-1118
Publication Date(Web):02 Dec 2015
DOI:10.1039/C5TA08166A
Recently, flexible electrolytes have aroused tremendous interest due to their wide applications in flexible electronic devices, such as wearable electronics, roll-up displays, smart mobile devices and implantable biosensors. Herein, novel ionic liquids, whose both cations and anions both can be polymerized, are used to construct flexible poly(ionic liquid) hydrogel electrolytes by one-step synthesis. Originating from the ionic interactions inside the ionic liquids, these hydrogels combine strong and weak crosslinks after polymerization, which makes these hydrogels tough, stretchable, flexible and self-recoverable. Their superior mechanical properties have been certified by mechanical tests. Moreover, these poly(ionic liquid) hydrogels show extremely high ionic conductivities over 1 S m−1 at room temperature and low activation energy. Notably, their electrochemical behaviors can remain stable under different bending angles and successive bending, folding, compressing and twisting. As flexible electrolytes, these poly(ionic liquid) hydrogels give the possibility to be used in fuel cells or supercapacitors, thus, promoting the development of flexible electronic devices.
Co-reporter:Tao Zhou, Xinpei Gao, Fei Lu, Na Sun and Liqiang Zheng
New Journal of Chemistry 2016 vol. 40(Issue 2) pp:1169-1174
Publication Date(Web):10 Nov 2015
DOI:10.1039/C5NJ02432C
Ionogels, solid-like materials maintaining many of the physicochemical properties of ionic liquids, have aroused much interest as excellent functional materials. Here, a facile strategy of the preparation of supramolecular ionogels is reported. Benzenetricarboxylic acid (H3BTC) and Fe(NO3)3·9H2O are selected as gelators, which form stable supramolecular ionogels within several seconds via metal-coordination interactions in the ionic liquids 1-butyl-3-methylimidazolium chloride (bmimCl) and 1-butyl-3-methylimidazolium benzenesulfonate (bmimBsa). The time for preparing ionogels is reduced dramatically. The ionogel Fe–H3BTC–bmimCl is broken down at 100 °C, but the ionogel Fe–H3BTC–bmimBsa can remain stable at 150 °C, exhibiting high temperature durability. These ionogels are characterized further by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetry (TG) in detail. In addition, oscillatory rheological measurements and electrochemical measurements show that these ionogels display superior mechanical properties and high conductivity due to the high ionic liquid content.
Co-reporter:Yi Yang, Na Sun and Liqiang Zheng
RSC Advances 2016 vol. 6(Issue 64) pp:58890-58897
Publication Date(Web):15 Jun 2016
DOI:10.1039/C6RA11498A
The relationship between the grafting density of the hydrophobic side chain and the microstructure of proton exchange membranes (PEMs) has been investigated thoroughly. Compared with the poly(ionic liquid)/polyvinyl alcohol/caprylic acid-0 (PIL/PVA/CA-0) membrane, when the hydrophobic side chains are grafted onto PVA, the SAXS results show that the PIL/PVA/CA-m (m = 0.05, 0.1, 0.15) membrane can generate ionic clusters which is of benefit to proton conduction. Meanwhile, the PIL/PVA/CA-0.05 membrane shows a higher proton conductivity at the same temperature compared with other membranes; this is attributed to the aggregation of bigger ionic clusters which can facilitate the formation of interconnected broad ionic channels. The highest proton conductivity of the PIL/PVA/CA-0.05 membrane is 158 mS cm−1; it is higher than that of Nafion117 (129 mS cm−1 at 80 °C). Moreover, the high grafting density would reduce the tolerance of the PEM to the attack of OH˙, but lower water uptake is of benefit for improving the oxidative stability, this is induced by the entanglement of side chains under higher grafting density. We anticipate that this finding will shed new light on the design of polymer structures of PEMs and relevant electrochemical devices.
Co-reporter:Panpan Sun, Lijuan Shi, Fei Lu and Liqiang Zheng
RSC Advances 2016 vol. 6(Issue 33) pp:27370-27377
Publication Date(Web):10 Mar 2016
DOI:10.1039/C6RA02986H
A group of zwitterionic surface active ionic liquids (SAILs) with different counterions, cations and alkyl chains, 3-(1-alkyl-3-imidazolio)propanesulfonate β-naphthalene sulfonate, (CnIPS-Nsa, n = 12, 14), 3-(1-dodecyl-3-imidazolio)propanesulfonate benzenesulfonate (C12IPS-Bsa), and dodecyl-N,N-dimethylammonio-3-propane sulfonate β-naphthalene sulfonate (SB-12-Nsa), were synthesized. Their aggregation behaviors in aqueous solutions were systematically investigated by surface tension, dynamic light scattering (DLS) and 1H NMR spectroscopy. Surface tension and DLS results illustrated that the surface properties, micelle size, and micellization behavior of zwitterionic SAILs in aqueous solutions are significantly affected by the anion type, anionic structure and the hydrophobicity of the alkyl chain. The SAILs with more hydrophobic anions and long alkyl chains are expected to favor the micellization. The steric hindrance and hydrophobicity of the cations, as well as the binding strength of the cations with the anions, also play important roles in the aggregation of zwitterionic SAILs. Additionally, the micelle formation mechanism was acquired by detailed analysis of the 1H NMR spectra. The existence of π–π stacking between imidazolium and counterions was proved. The enhanced π–π stacking and hydrophobic effect of Nsa− can promote the aggregation of zwitterionic SAILs. Density functional theory (DFT) calculations illustrated that the negative interaction energy of the complexes were C12IPS-Bsa/H2O > SB-12-Nsa/H2O > C12IPS-Nsa/H2O > C14IPS-Nsa/H2O. It is more difficult to form micelles in complexes with more negative interaction energy. The counterion electronegativity of Nsa− is smaller than that of Bsa−, which favors the formation of micelles.
Co-reporter:Yi Yang, Na Sun, Panpan Sun and Liqiang Zheng
RSC Advances 2016 vol. 6(Issue 30) pp:25311-25318
Publication Date(Web):03 Mar 2016
DOI:10.1039/C6RA02033J
A novel poly(ionic liquid) (PIL) based on bis-imidazolium is designed to improve the performances of alkaline anion exchange membrane (AAEM). As a result, the bis-imidazolium-based PILs AAEMs (PVA/DCnPIL) exhibit lower swelling ratio (higher dimensional stability) and higher chemical stability than that of mono-imidazolium-based PIL AAEM (PVA/C4PIL) under the same IEC value. Meanwhile, the length of the side chains of PILs was changed from the double imidazolium, which induces a different microstructure that can affect the ionic conductivity and stability obviously. The SAXS results show that the PVA/DC8PIL can generate larger ionic clusters for facilitating the formation of interconnected broad ionic channels, which leads to higher conductivity in comparison with the PVA/DCnPIL (n = 4, 12) membranes. These observations unambiguously indicate that the designed bis-imidazolium-based PIL with an appropriate length of hydrophobic chains is an effective approach to increase the ion conductivity, dimensional and chemical stability of AAEMs.
Co-reporter:Xinpei Gao, Fei Lu, Wenjiang Yang, Fengkang Shang and Liqiang Zheng
RSC Advances 2016 vol. 6(Issue 72) pp:67495-67501
Publication Date(Web):12 Jul 2016
DOI:10.1039/C6RA11193A
A wormlike micelle templated attachment growth approach for the preparation of mono- and bi-metallic nanochain networks is reported. Zwitterionic wormlike micelles with PtCl62− and PdCl42− counterions were fabricated for the first time as soft-templates. A possible soft-template assisted attachment-based growth mechanism for nanochain formation is proposed for the morphological replica process. The present strategy was further extended to synthesize alloyed noble-metal such as Pt–Au, Pd–Au, and Pt–Pd nanochain networks. The results presented may provide inspirations and strategies for the fabrication of noble metal nanostructures with adjustable structures and constituents through soft templated attachment growth.
Co-reporter:Aoli Wu, Fei Lu, Panpan Sun, Xinpei Gao, Lijuan Shi, and Liqiang Zheng
Langmuir 2016 Volume 32(Issue 32) pp:8163-8170
Publication Date(Web):July 22, 2016
DOI:10.1021/acs.langmuir.6b01937
A novel photoresponsive surface active ionic liquid (SAIL) 1-(4-methyl azobenzene)-3-tetradecylimidazolium bromide ([C14mimAzo]Br) with azobenzene located in the headgroup was designed. Reversible vesicle formation and rupture can be finely controlled by photostimuli without any additives in the aqueous solution of the single-tailed ionic liquid. The photoisomerization of the azobenzene derivative was investigated by 1H NMR and UV–vis spectroscopy. Density functional theory (DFT) calculations further demonstrate that trans-[C14mimAzo]Br has less negative interaction energy, which is beneficial to aggregate formation in water. The incorporation of trans-azobenzene group increases the hydrophobicity of the headgroup and reduces the electrostatic repulsion by delocalization of charge, which are beneficial to the formation of vesicles. However, the bend of cis-azobenzene makes the cis-isomers have no ability to accumulate tightly, which induces the rupture of vesicles. Our work paves a convenient way to achieve controlled topologies and self-assembly of single SAIL.
Co-reporter:Xinpei Gao, Fei Lu, Bin Dong, Yizhi Liu, Yanan Gao and Liqiang Zheng
Chemical Communications 2015 vol. 51(Issue 5) pp:843-846
Publication Date(Web):21 Nov 2014
DOI:10.1039/C4CC08549C
Zwitterionic wormlike micelles with AuCl4− counterions were fabricated for the first time as the soft templates for colloidal synthesis of gold nanowire networks; gold-based alloy nanowire networks were also achieved using mixed wormlike micelles as soft templates.
Co-reporter:Lijuan Shi, Fuyu Chen, Nan Sun and Liqiang Zheng
Soft Matter 2015 vol. 11(Issue 20) pp:4075-4080
Publication Date(Web):17 Apr 2015
DOI:10.1039/C5SM00658A
Novel gemini supra-amphiphiles, [Mim-4-Mim][DBS]2 and [Mim-4-Mim][DS]2, were facilely constructed. A slight variation of building blocks can effectively modulate the driving forces for the fabrication of gemini supra-amphiphiles, thus leading to the fine control of subsequent self-assemblies. [Mim-4-Mim][DS]2, constructed via electrostatic attraction, tends to form micelles and hexagonal liquid crystals. Rich lamellar structures, including unilamellar and multilamellar vesicles, planar bilayers, and lamellar liquid crystals can be formed by [Mim-4-Mim][DBS]2, which is constructed through electrostatic and π–π stacking interactions. With increasing temperatures, [Mim-4-Mim][DBS]2 exhibits interesting phase separation in the La phase, behaving like common nonionic surfactants. The cross-linking between vesicles, where the “bola-type” [Mim-4-Mim]2+ cations act as the bridges, was found to promote the elongation of aggregates until the occurrence of phase separation.
Co-reporter:Shuting Xie, Han Jia, Fei Lu, Nan Sun, Jierui Yu, Shaojie Liu and Liqiang Zheng
CrystEngComm 2015 vol. 17(Issue 5) pp:1210-1218
Publication Date(Web):09 Dec 2014
DOI:10.1039/C4CE02033B
Well-dispersed α-Fe2O3 nanostructures with controlled dimensionality and shape have been successfully prepared via a facile and environmentally friendly solvothermal route with the assistance of 1-N-butyl-3-methylimidazolium benzoate ([Bmim][PhCOO]). A significant advancement has been made in tailoring dendritic α-Fe2O3 nanostructures along {110} directions. The dendrites can be tailored to hexagonal plates and rods only by changing the molar ratio of [Bmim][PhCOO] to K3[Fe(CN)6] from 0:1 to 2:1, and 5:1. [Bmim][PhCOO] is found to play a key role in the evolution of α-Fe2O3 with different shapes: the nucleation rate is influenced by the hydrolysis of [PhCOO]− anions, and the [Bmim]+ cations can favorably stabilize the {110} facets due to the hydrogen bond-co-π–π stacking interaction. A possible mechanism was proposed. Furthermore, the visible light induced photodegradation of RhB reveals that α-Fe2O3 rods exhibit higher photocatalytic activity compared to dendrites and plates. Interestingly, with the process proceeding, the photoactivity of these samples increases successively. The enhancement of photocatalytic performance may be due to the different exposed crystal facets of α-Fe2O3 nanostructures and the degree of crystallinity. The tailoring process gives us an in-depth understanding of the formation mechanism of dendritic α-Fe2O3 structures, which is not possibly achieved by the traditional time-dependent method, and it is highly expected that this study will suggest a promising new strategy for engineering practical photocatalysts for wastewater treatment.
Co-reporter:Xinpei Gao, Fei Lu, Bin Dong, Tao Zhou, Yizhi Liu and Liqiang Zheng
RSC Advances 2015 vol. 5(Issue 78) pp:63732-63737
Publication Date(Web):20 Jul 2015
DOI:10.1039/C5RA10830F
In the present study, we synthesized a series of ionic liquids by mixing amphiphilic imidazolium-type zwitterions with sulfonic acids containing different substituent groups. Nanostructured proton conductors having hexagonal and cubic structures were constructed by the self-assembly of these zwitterionic ionic liquids. These nanostructured proton conductors exhibited an assembled-structure dependent proton conduction behavior. The introduction of highly ordered liquid crystal structures efficiently improved ionic conductivity, suggesting the induction of proton conduction through a hopping mechanism. Temperature-responsive ionic conductivity behavior based on phase transition within the self-assembled liquid crystal structures was also observed.
Co-reporter:Yi Yang, Hejun Gao and Liqiang Zheng
RSC Advances 2015 vol. 5(Issue 23) pp:17683-17689
Publication Date(Web):26 Jan 2015
DOI:10.1039/C4RA16106H
A series of novel anhydrous proton exchange membranes (poly(vinyl alcohol)–citric acid–ionic liquid (PVA–CA–IL)) were prepared using the low cost ionic liquids ethylammonium nitrate (EAN), diethylammonium nitrate (DEAN), and triethylammonium nitrate (TEAN) as conductive fillers in PVA support membrane. The properties of the PVA–CA–IL membranes can be controlled by changing the molar ratio of the PVA, ILs and CA. The thermal stability of PVA–CA–IL membrane was measured by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), and the microstructure was investigated using scanning electron microscopy (SEM) and the Anton-paar SAX Sess mc2 system (SAXS). The effects of temperature, ILs and crosslinker dosage on proton conductivity were also systematically investigated. The results showed that the PVA–CA–IL membranes had excellent performance. The proton conductivity of PVA–CA–EAN (mole ratio = 1:0.05:0.4) could reach up to 7.8 mS cm−1 at 140 °C. The introduction of ionic liquid into PVA membrane constituted a new and efficient kind of anhydrous proton exchange membrane.
Co-reporter:Hongtao Zhou, Han Jia, Ailing Zhang, Liping Zhang, Cunqi Jia, Liqiang Zheng
Journal of Molecular Liquids 2015 Volume 208() pp:27-33
Publication Date(Web):August 2015
DOI:10.1016/j.molliq.2015.04.028
•The interconversion between gold nanostars and gold nanodendrites can be achieved.•The high temperature is beneficial for the fabrications of gold nanodendrites.•The electrostatic action between capping agents can affect the final morphology.•The gold nanodendrites with larger aspect ratio are more suitable as SERS substrates.Gold nanostars and gold nanodendrites were readily synthesized by the reduction of HAuCl4 with ascorbic acid in aqueous mixed solutions of the cationic surfactant decane-1,10-bis(methylpyrrolidinium bromide) ([mpy-C10-mpy]Br2) and the anionic surfactant sodium dodecyl sulfonate (SDS). The interconversion of morphologies between gold nanostars and gold nanodendrites can be achieved by changing the reaction temperature under the otherwise identical conditions, which is seldom reported. Due to the electrostatic interaction, the introduction of SDS brought the dramatic impact to the formation process and the final morphologies of the gold nanostructures. Both of the hierarchical structures were found to yield large surface-enhanced Raman scattering (SERS) enhancement factors for rhodamine 6G (R6G) and the aspect ratio is a key factor for the enhancement.By changing the reaction temperature and the concentration of SDS, the morphological interconversion between gold nanostars and gold nanodendrites was successfully achieved.
Co-reporter:Han Yan, Bin Zhao, Yue Long, Liqiang Zheng, Chen-Ho Tung, Kai Song
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2015 Volume 482() pp:639-646
Publication Date(Web):5 October 2015
DOI:10.1016/j.colsurfa.2015.07.004
•Both hydrophilic and amphiphilic silica nanowires were synthesized via a wet-chemical process.•Pickering emulsions were prepared by use of the two types of silica nanowires.•Emulsions stabilized by amphiphilic nanowires show exceptional stability for over 4 months.In this work, oil-in-water and water-in-oil emulsions stabilized by hydrophilic and amphiphilic silica nanowires separately were investigated by scanning electron microscopy (SEM), optical microscopy and visual observation. The effects of length, concentration and wettability of the nanowires on the stabilization of the emulsion were investigated. The hydrophilic silica nanowires of 10 μm length can be used to prepare stable oil-in-water emulsions, with a network forming on the surface of the emulsion droplet is believed to be beneficial for the emulsion stability; whereas, the amphiphilic silica nanowires of all three lengths (1.5, 2.5 and 5 μm) can produce water-in-oil emulsions stable for at least 4 months, and it was found that increasing either the length or concentration of silica nanowires resulted in the enhancement of the stabilization of emulsions by nanowires. Phase inversion from oil-in-water to water-in-oil can be easily achieved by increasing the oil volume fraction in the amphiphilic silica nanowire stabilized emulsions.Pickering emulsions stabilized by hydrophilic and amphiphilic silica nanowires separately were prepared. The effect of length and concentration of the nanowires, and oil/water volume ratio on the stability of the emulsion were investigated.
Co-reporter:Nan Sun, Lijuan Shi, Fei Lu, Shuting Xie, Panpan Sun, and Liqiang Zheng
Langmuir 2015 Volume 31(Issue 8) pp:2281-2287
Publication Date(Web):February 10, 2015
DOI:10.1021/la504913v
In the present work, we reported a novel linear pseudo-oligomeric surfactant, which is formed by mixing dodecyl benzenesulfonate (SDBS) and a linear tricationic imidazolium bromide salt (LTIB) in a molar ratio of 3:1. The aggregation behavior, aggregate structures, and interactions between SDBS and LTIB were investigated by surface tension measurement, dynamic light scattering, turbidity, cryogenic transmission electron microscopy, and 1H NMR techniques. When SDBS is mixed with LTIB in aqueous solutions, three SDBS molecules may be “bridged” to one cationic LTIB molecule by intermolecular interactions, behaving like a linear oligomeric surfactant. Vesicles can be formed by this kind of linear pseudo-oligomeric surfactant. The aggregation behavior of the LTIB/SDBS mixed aqueous solutions behaves ratio- and concentration- dependence. Our work paves a convenient way for constructing surfactant systems with the characteristics of linear pseudo-oligomeric surfactant through intermolecular interactions between commercially available single-chain surfactants and linear tricationic imidazolium counterions.
Co-reporter:Xiu-Jie Yang, Bin Chen, Li-Qiang Zheng, Li-Zhu Wu and Chen-Ho Tung
Green Chemistry 2014 vol. 16(Issue 3) pp:1082-1086
Publication Date(Web):05 Nov 2013
DOI:10.1039/C3GC42042F
We report a simple but efficient photocatalytic nitrobenzene reduction method employing eosin Y as the photocatalyst and TEOA as the reducing agent. With green LED light irradiation, the nitro group in the nitrobenzenes containing other reducible groups was chemoselectively reduced into an amino group, and the corresponding anilines were isolated in quantitative yields. The photoinduced electron transfer mechanism suggests that the high chemoselectivity originates from the better electron-withdrawing ability of the nitro group.
Co-reporter:Xinpei Gao, Fei Lu, Bin Dong, Tao Zhou, Wenfei Tian and Liqiang Zheng
Chemical Communications 2014 vol. 50(Issue 63) pp:8783-8786
Publication Date(Web):17 Jun 2014
DOI:10.1039/C4CC03626C
Zwitterionic vesicles with AuCl4− counterions were fabricated for the first time as the soft templates for colloidal synthesis of gold nanostructures; gold nanoplates spontaneously generated at the vesicle bilayers were observed and gold nanospheres were achieved via a stepwise reduction approach.
Co-reporter:Xiu-Jie Yang, Bin Chen, Xu-Bing Li, Li-Qiang Zheng, Li-Zhu Wu and Chen-Ho Tung
Chemical Communications 2014 vol. 50(Issue 50) pp:6664-6667
Publication Date(Web):06 May 2014
DOI:10.1039/C4CC01671H
We report the first application of layered double hydroxide as a photocatalyst in the transformation of primary aromatic amines to their corresponding imines with high efficiency and selectivity by using oxygen in an air atmosphere as a terminal oxidant under light irradiation.
Co-reporter:Fei Lu, Xinpei Gao, Bin Dong, Panpan Sun, Nan Sun, Shuting Xie, and Liqiang Zheng
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 24) pp:21970
Publication Date(Web):December 3, 2014
DOI:10.1021/am504504m
Ionic liquid crystals (ILCs) with hexagonal and lamellar phases were successfully fabricated by the self-assembly of a polymerizable amphiphilic zwitterion, which is formed by 3-(1-vinyl-3-imidazolio)propanesulfonate (VIPS) and 4-dodecyl benzenesulfonic acid (DBSA) based on intermolecular electrostatic interactions. The microstructures and phase behaviors of ILCs were studied by polarized microscope (POM) and small-angle X-ray scattering (SAXS). The ILC topological structures can be considered as proton pathways and further fixed by photopolymerization to prepare nanostructured proton-conductive films. The introduction of highly ordered and well-defined ILC structures into these polymeric films radically improves the ionic conductivities.Keywords: ionic liquid crystals; photopolymerization; proton-conductors; self-assembly; zwitterions
Co-reporter:Shuting Xie, Fei Lu, Nan Sun, Shaojie Liu, Han Jia and Liqiang Zheng
CrystEngComm 2014 vol. 16(Issue 41) pp:9727-9734
Publication Date(Web):01 Sep 2014
DOI:10.1039/C4CE01177E
Hierarchical α-Fe2O3 nanostructures have been successfully synthesized in aqueous solution of sodium dodecyl sulfonate (SDS), 1-dodecyl-3-methylimidazolium bromide (C12mimBr) and ethylene glycol (EG) on the basis of a polyol process. Based on a series of experiments, the possible growth mechanism and fabrication process of the hierarchical structures were proposed. The addition of EG and utilizing Fe2+ ions as the source of iron were our “protection” reactions to guarantee the equilibrium between hydrolysis and oxidation of Fe3+. Furthermore, electrochemical measurements demonstrated that the as-prepared hierarchical α-Fe2O3 nanocrystals are ideal candidates for lithium-ion batteries. In addition, the photocatalytic activity of the as-prepared α-Fe2O3 was superior to that of the previously reported hierarchical α-Fe2O3 nanomaterials and the Fe2O3-based photocatalyst (α-Fe2O3/SnO2).
Co-reporter:Nan Sun, Lijuan Shi, Fei Lu, Shuting Xie and Liqiang Zheng
Soft Matter 2014 vol. 10(Issue 30) pp:5463-5471
Publication Date(Web):25 Apr 2014
DOI:10.1039/C4SM00565A
The phase behavior of a kind of pseudogemini surfactant in aqueous solutions, formed by the mixture of sodium dodecyl benzene sulfonate (SDBS) and butane-1,4-bis (methylimidazolium bromide) ([mim-C4-mim]Br2) or butane-1,4-bis(methylpyrrolidinium bromide) ([mpy-C4-mpy]Br2) in a molar ratio of 2:1, is reported in the present work. When [mim-C4-mim]Br2 or [mpy-C4-mpy]Br2 is mixed with SDBS in aqueous solutions, one cationic [mim-C4-mim]Br2 or [mpy-C4-mpy]Br2 molecule “bridges” two SDBS molecules by noncovalent interactions (e.g. electrostatic, π–π stacking, and σ–π interactions), behaving like a pseudogemini surfactant. Vesicles can be formed by this kind of pseudogemini surfactant, determined by freeze-fracture transmission electron microscopy (FF-TEM) or cryogenic-transmission electron microscopy (cryo-TEM) and dynamic light scattering (DLS). The mixed system of sodium dodecyl sulfate (SDS) with [mim-C4-mim]Br2 or [mpy-C4-mpy]Br2 was also constructed, and only micelles were observed. We infer that a pseudogemini surfactant is formed under the synergic effect of electrostatic, π–π stacking, and σ–π interactions in the SDBS/[mim-C4-mim]Br2/H2O system, while electrostatic attraction and hydrophobic interactions may provide the directional force for vesicle formation in the SDBS/[mpy-C4-mpy]Br2/H2O system.
Co-reporter:Han Yan, Yue Long, Kai Song, Chen-Ho Tung and Liqiang Zheng
Soft Matter 2014 vol. 10(Issue 1) pp:115-121
Publication Date(Web):16 Oct 2013
DOI:10.1039/C3SM52346B
A UV-induced self-assembly based on N-methyl-N-cetylpyrrolidinium bromide (C16MPBr) and sodium (4-phenylazo-phenoxy)-acetate (AzoNa) was fabricated in the present work through facile mixing of C16MPBr and trans-AzoNa in water. Due to the trans–cis photoisomerization functionality of the AzoNa, this self-assembly possesses photo-responsive properties. Under ambient conditions, the morphology of the self-assembly was wormlike micelles with a high viscosity of about 10 Pa s, whereas after applying UV light, the self-assembly transformed into spherical micelles with a dramatically lowered viscosity of about 0.01 Pa s. Different from most reported photo-responsive wormlike micelles consisting of conventional cationic surfactant CTAB, our system was constructed from a novel pyrrolidinium ionic liquid. We hope this study may provide a deeper understanding of photo-responsive wormlike micelles constructed by cationic surfactants and photo-sensitive additives in water.
Co-reporter:Yi Yang, Hejun Gao, Fei Lu, Liqiang Zheng
International Journal of Hydrogen Energy 2014 Volume 39(Issue 30) pp:17191-17200
Publication Date(Web):13 October 2014
DOI:10.1016/j.ijhydene.2014.08.055
•Cross-linked membrane was prepared successfully for ionic directional conduction.•The conductivity of the membrane enhances obviously by ionic directional conduction.•Alcohol resistance performance of the directional conducting membrane is better.•The proton directional conducting membrane exhibits high oxidative stability.To produce directional conducting and lower methanol permeable ultrathin membrane for fuel cell, the imidazolium salt as both cross-linking agent and proton donor has been designed to build a directional proton conducting channel in a poly (vinyl alcohol)-based membrane. The methanol permeability of directional conducting membrane is very low, which is about twice smaller than that of Nafion117. In addition, the membranes show a relatively high oxidative durability in H2O2 solutions, with only about 10% weight loss after the membrane being immersed in 3% H2O2 solution for 120 h. All the properties of prepared directional conducting membrane indicate their promising prospects in proton conducting membrane applications.
Co-reporter:Hongtao Zhou, Hui Yan, Ailing Zhang, Liqiang Zheng, Han Jia
Materials Chemistry and Physics 2014 Volume 148(Issue 3) pp:503-506
Publication Date(Web):15 December 2014
DOI:10.1016/j.matchemphys.2014.08.060
•The π–π stacking interactions play important roles in the assembly of gold nanorods.•The energy calculation demonstrated the stability of face–face stacked orientation.•The assembly fashion of gold nanorods can be tuned from end-to-end to side-by-side.Gold nanorods have been recognized as a good candidate for developing novel nanomaterials due to their exceptional optical properties. However, their assemblies, especially with the assisted ionic liquid, have not been well characterized. In this paper, we report the self-assembly of gold nanorods using thiol-functionalized ionic liquid (1-methyl-3-(2′-mercaptoacetoxyethyl) imidazolium bromine) (TFIL). We found that gold nanorods can self-assemble via two different ways: From end-to-end to side-by-side with the increase of TFIL concentration. The shift of the absorption peak in UV–vis spectrum indicates the change of the assembly fashion. We propose that the π–π stacking interactions between the imidazole rings of TFIL molecules play the most important role in regulating the assembly process. The energy calculation further demonstrated that the face–face stacked orientation was the most stable geometry at high TFIL concentration, which supports the proposed mechanism. These gold nanorod assemblies were shown to yield the large SERS enhancements for Rhodamine 6G.
Co-reporter:Fei Lu, Lijuan Shi, Han Yan, Xiujie Yang, Liqiang Zheng
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2014 Volume 457() pp:203-211
Publication Date(Web):5 September 2014
DOI:10.1016/j.colsurfa.2014.05.071
•A kind of room-temperature ILs with aromatic anions was successfully synthesized.•The aromatic ILs affect the micellization of a surfactant with aromatic headgroups.•The enhanced π–π stacking interaction and hydrophobic interaction play a key role.The effects of ionic liquids (ILs), 1-butyl-3-methylimidazolium acetate ([Bmim][OAc]) and 1-butyl-3-methylimidazolium benzoate ([Bmim][PhCOO]) on the aggregation behavior of dodecyltriphenylphosphonium bromide (C12TPB) in aqueous solution were investigated by surface tension measurements, dynamic light scattering (DLS) measurements and 1H NMR spectroscopy. The introduction of benzene rings in the anions of [Bmim][PhCOO] can promote the micellization of C12TPB more efficiently with a smaller CMC value and a bigger micellar size. The 1H NMR spectra revealed that [Bmim][PhCOO] can participate in the micelle formation. The combined effect of intermolecular interactions, such as electrostatic attraction, hydrophobic effect and π–π stacking interaction is proposed to be responsible for the enhancement in the micellization of C12TPB.Surface tension curves of C12TPB/[Bmim][PhCOO] system and the proposed mechanism.
Co-reporter:Yi Yang;Hejun Gao;Fei Lu
Colloid and Polymer Science 2014 Volume 292( Issue 11) pp:2831-2839
Publication Date(Web):2014 November
DOI:10.1007/s00396-014-3324-7
Poly-(vinyl alcohol) (PVA) proton-conducting composite membranes were prepared using succinic acid (SA) as a cross-linking agent and Brønsted acidic ionic liquid (BAIL) as a proton source. The incorporated BAILs resulted in a relatively high proton conductivity compared with PVA/SA membrane without BAILs. The proton conductivities of PVA/SA/BAIL composite membranes increased versus the BAIL content. In addition, the optimal resultant proton conductivity of PVA/SA/BAIL composite membrane under dry condition could reach 0.4 mS/cm at 140 °C, which was higher than that of PVA/sulfosuccinic acid (SSA) composite membrane (0.032 mS/cm), PVA/SSA/5-aminotetrazole membrane (0.022 mS/cm at 130 °C), and PVA/chlorosulfonic acid/glutaraldehyde membrane (0.0585 mS/cm at 90 °C) measured at the same condition. It was notable that the PVA/SA/BAIL composite membranes could reach high thermal stability up to 150 °C, which was higher than that of traditional PVA membranes (below 80 °C).
Co-reporter:Lijuan Shi, Ying Wei, Nan Sun and Liqiang Zheng
Chemical Communications 2013 vol. 49(Issue 97) pp:11388-11390
Publication Date(Web):15 Oct 2013
DOI:10.1039/C3CC45550E
It was found for the first time that rich lamellar structures are formed by a single-tailed amphiphilic ionic liquid (IL), 1-dodecyl-3-methylimidazolium β-naphthalene sulfonate ([C12mim][Nsa]), in aqueous solutions without any additives. With increasing IL concentration, spontaneous transition from micelles to unilamellar and multilamellar vesicles, planar bilayers, and then to lamellar liquid crystals occurs.
Co-reporter:Fei Lu, Xinpei Gao, Xiaojun Yan, Hejun Gao, Lijuan Shi, Han Jia, and Liqiang Zheng
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 15) pp:7626
Publication Date(Web):July 16, 2013
DOI:10.1021/am401940y
Hybrid Nafion membranes were successfully fabricated by incorporating with protic imidazolium ionic liquids 1-(2-aminoethyl)-3-methylimidazolium chloride ([MimAE]Cl), 1-(2-hydroxylethyl)-3-methylimidazolium chloride ([MimHE]Cl), and 1-carboxylmethyl-3-methylimidazolium chloride ([MimCM]Cl) for high-temperature fuel cells. The composite membranes were characterized by impedance spectroscopy, small-angle X-ray scattering (SAXS), scanning electronic microscopy (SEM), and thermogravimetric analysis (TGA). The incorporated protic ionic liquids enhance the doping of phosphoric acid (PA) and result in a relatively high ionic conductivity. The Nafion/10 wt % [MimAE]Cl/PA composite membrane exhibits an ionic conductivity of 6.0 mS/cm at 130 °C without humidification. [MimAE]Cl can swell the Nafion matrix more homogeneously than [MimHE]Cl or [MimCM]Cl, which results in a better ionic conductivity. It is notable that the composite Nafion/IL/PA membranes have a better thermal stability than the pristine Nafion membranes.Keywords: anhydrous condition; composite membranes; ionic conductivity; nafion; protic ionic liquids; SAXS;
Co-reporter:Xinpei Gao, Fei Lu, Lijuan Shi, Han Jia, Hejun Gao, and Liqiang Zheng
ACS Applied Materials & Interfaces 2013 Volume 5(Issue 24) pp:13312
Publication Date(Web):November 15, 2013
DOI:10.1021/am404288x
In the present study, we have synthesized a room-temperature ionic liquid by mixing imidazolium-type zwitterions with lithium bis(trifluoromethanesulfonyl)imide. We constructed nanostructured aqueous lithium-ion conductors having hexagonal, lamellar, and bicontinuous cubic structures by the self-assembly of this amphiphilic ionic liquid. These nanostructured lithium-ion conductors exhibited an assembled-structure dependent lithium-ion conduction behavior. The introduction of highly ordered and well-defined liquid crystal structures into room-temperature ionic liquid radically changes the conduction mechanism from diffusion to hopping.Keywords: electrolyte; ionic liquid crystals; ionic liquids; self-assembly; zwitterions;
Co-reporter:Xiujie Yang;Xinwei Li;Bin Chen;Lizhu Wu;Liping Zhang;Chenho Tung
Chinese Journal of Chemistry 2013 Volume 31( Issue 5) pp:603-606
Publication Date(Web):
DOI:10.1002/cjoc.201300275
Abstract
Irradiation of cyclohexyl phenyl ketone (1) results in either intra- or intermolecular hydrogen abstraction to afford compounds 1-phenylhept-6-en-1-one (2) and α-cyclohexyl benzyl alcohol (3) as photoproducts, in which 3 has a pair of enantiomers. Herein, two types of chiral hexagonal liquid crystals were prepared to direct the enantioselective photochemical reaction of 1. One of the hexagonal liquid crystals is composed of 1-tetradecyl-3-methylimidazolium bromide/p-xylene/H2O with the modification by a chiral inductor. The other one is formed by chiral (S)-3-hexadecyl-1-(1-hydroxy-propan-2-yl)-imidazolium bromide/p-xylene/H2O. The product analysis shows that the latter one can be used as a microreactor to achieve stereoselective photochemical reaction, while the former one produced compound 3 with no enantioselectivity at all.
Co-reporter:Yingqiu Gu, Lijuan Shi, Xiyuan Cheng, Fei Lu, and Liqiang Zheng
Langmuir 2013 Volume 29(Issue 21) pp:6213-6220
Publication Date(Web):May 3, 2013
DOI:10.1021/la400497r
The effects of ionic liquids (ILs), 1-butyl-3-methylimidazolium methylsulfonate (bmimMsa), 1-butyl-3-methylimidazolium benzenesulfonate (bmimBsa), and 1-butyl-3-methylimidazolium 2-naphthalenesulfonate (bmimNsa), on the aggregation behavior of 1-dodecyl-3-methylimidazolium bromide (C12mimBr) in aqueous solution were investigated by surface tension, dynamic light scattering measurements, and 1H NMR spectroscopy. The ability to promote the surfactant aggregation is in the order bmimNsa > bmimBsa > bmimMsa. Nevertheless, only bmimNsa distinctly reduces both the CMC value and the surface tension at CMC. Due to the penetration of C10H7SO3–anions into the surfactant aggregate, bmimNsa is found to induce a phase transition from micelles to vesicles, whereas the other ILs only slightly increase the sizes of micelles. The combined effect of intermolecular interactions, such as hydrophobic effect, electrostatic attractions, and π–π stacking interactions, is supposed to be responsible for this structural transformation, in which π–π stacking plays an important role.
Co-reporter:Yingqiu Gu, Lijuan Shi, Hejun Gao, Jun Li, Liqiang Zheng
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2013 420() pp: 82-88
Publication Date(Web):
DOI:10.1016/j.colsurfa.2012.12.026
Co-reporter:Dr. Mingwei Zhao;Dr. Yurong Zhao; Liqiang Zheng; Caili Dai
Chemistry - A European Journal 2013 Volume 19( Issue 3) pp:1076-1081
Publication Date(Web):
DOI:10.1002/chem.201203062
Abstract
Highly ordered supramolecular microfibers were constructed through a simple ionic self-assembly strategy from complexes of the N-tetradecyl-N-methylpyrrolidinium bromide (C14MPB) surface-active ionic liquid and the small methyl orange (MO) dye molecule, with the aid of patent blue VF sodium salt. By using scanning electron microscopy and polarized optical microscopy, the width of these self-assembled microfibers is observed to be about 1 to 5 μm and their length is from tens of micrometers to almost a millimeter. The 1H NMR spectra of the microfibers indicates that the supramolecular complexes are composed of C14MPB and MO in equal molar ratio. The electrostatic, hydrophobic, and π–π stacking interactions are regarded as the main driving forces for the formation of microfibers. Furthermore, through characterization by using confocal fluorescence microscopy, the microfibers were observed to show strong fluorescent properties and may find potential applications in many fields.
Co-reporter:Hejun Gao;Lijuan Shi;Shaohua Zhang;Jun Li;Xiaodong Wang
Colloid and Polymer Science 2013 Volume 291( Issue 5) pp:1077-1084
Publication Date(Web):2013 May
DOI:10.1007/s00396-012-2830-8
A novel imidazolium-based chiral surfactant with a Y-type hydrophobic chain, (S)-(+)-1-(2,3-bis(octanoyloxy)propyl)-3-methylimidazolium chloride ([Bopmim]Cl), was synthesized. The aggregation behavior of [Bopmim]Cl in aqueous solution was then investigated by surface tension, electrical conductivity, 1H NMR, and fluorescence measurements. Compared with [C12mim]Cl, the critical micelle concentration for [Bopmim]Cl is lower, indicating that the novel chiral surfactant has superior capacity to form micelles. A larger value of pC20, a greater minimum area per surfactant molecule (Amin), a smaller degree of counterion binding (β), and a looser aggregate are caused by the relatively larger Y-type hydrophobic chain of [Bopmim]Cl. Furthermore, analysis of the 1H NMR spectra revealed that the introduced Y-type hydrophobic chain may prevent the hydrophobic group from forming an extended chain configuration and cause a changeover from trans to gauche conformations upon micellization. The micelles of the novel chiral surfactant may provide some potential applications in the stereochemical recognition of surfaces or of biological structures.
Co-reporter:Lijuan Shi;Xinxin Jing;Hejun Gao;Yingqiu Gu
Colloid and Polymer Science 2013 Volume 291( Issue 7) pp:1601-1612
Publication Date(Web):2013 July
DOI:10.1007/s00396-013-2894-0
The effects of ionic liquids 1-(2-aminoethyl)-3-methylimidazolium chloride ([MimAE]Cl), 1-carboxylmethyl-3-methylimidazolium chloride ([MimCM]Cl), 1-(2-hydroxylethyl)-3-methylimidazolium chloride ([MimHE]Cl), and 1-ethyl-3-methylimidazolium chloride ([Emim]Cl) on the physicochemical properties of aqueous sodium dodecyl sulfate (SDS) solutions were studied. Compared with [Emim]Cl, the presence of amino group can further facilitate the micellization of SDS, while the opposite result is observed as carboxyl group is imparted. No obvious changes in critical micelle concentration (CMC) and \( {\gamma_{\mathrm{CMC}}} \) values are induced by the neutral hydroxyl group. Only the addition of [MimAE]Cl drastically increases the micellar size. Significant decrease in CMC and increase in micellar size were observed with decreasing pH of [MimAE]Cl solution. The increase in pH of [MimCM]Cl solution results in a slight increase in CMC and decrease in micellar size. 1H NMR spectra revealed the amino groups are adsorbed at the micellar surface, while the carboxyl groups/carboxylate ions and hydroxyl groups tend to point towards bulk water.
Co-reporter:Fei Lu;Lijuan Shi;Yingqiu Gu;Xiujie Yang
Colloid and Polymer Science 2013 Volume 291( Issue 10) pp:2375-2384
Publication Date(Web):2013 October
DOI:10.1007/s00396-013-2986-x
The aggregation behavior of alkyltriphenylphonium bromides, CnTPB (n = 12 and 14), has been investigated in two different room-temperature ionic liquids (ILs), the aprotic 1-butyl-3-metyllimidazolium tetrafluoroborate ([bmim][BF4]), and the protic ethylammonium nitrate (EAN). The critical micelle concentration was determined by the surface tension measurements. The calculated thermodynamic parameters based on surface tension measurements at various temperatures indicate that the micellization for CnTPB in both aprotic [bmim][BF4] and protic EAN is enthalpy-driven. But stronger solvophobic interactions presented between CnTPB and protic EAN than aprotic [bmim][BF4]. 1H NMR spectra were further conducted to reveal that ethylammonium cation can insert into the micelle while imidazole cation only locates among the head groups of CnTPB.
Co-reporter:Han Jia, Xiangtao Bai, Lijuan Shi, Fei Lu and Liqiang Zheng
Nanoscale 2012 vol. 4(Issue 10) pp:3162-3167
Publication Date(Web):02 Apr 2012
DOI:10.1039/C2NR30286A
Benzyl-n-hexadecyl dimethylammonium chloride (BHDC) monolayer-stabilized gold nanoparticles were synthesized in a two-phase liquid–liquid system and found to self-assemble into varied structures under the control of temperature at the air–water interface. It has been demonstrated that the π–π stacking interactions between the capping agent molecules significantly affect the formation of the unique patterns. A possible mechanism based on Marangoni–Bénard convection in the evaporating droplets and π–π stacking interactions was proposed. Four surfactants with similar structures: N-hexadecyl-N-methylpyrrolidinium bromide (C16MPB), 1-hexadecyl-3-methylimidazolium bromide (C16mimBr), 1-(2,4,6-trimethylphenyl)-3-hexadecylimidazolium bromide (C16pimBr) and hexadecyltrimethylammonium bromide (CTAB) were also used to further verify the formation mechanism mentioned above.
Co-reporter:Fei Lu, Shaohua Zhang, Hejun Gao, Han Jia, and Liqiang Zheng
ACS Applied Materials & Interfaces 2012 Volume 4(Issue 6) pp:3278
Publication Date(Web):June 12, 2012
DOI:10.1021/am300634n
A globular protein, β-lactoglobulin (BLG), was used to decorate reduced graphene oxide sheets (RGO) and the obtained BLG-RGO composite can be dispersed in aqueous solution with pH-sensitive solubility. The morphology of the BLG-RGO composite was studied by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The results indicate that BLG-RGO is effectively exfoliated with an average thickness of 2.5 nm. UV–vis spectra were performed to examine the reduction degree and determine the optimum concentration of β-lactoglobulin and appropriate pH value. Furthermore, Raman spectra demonstrate that β-Lactoglobulin promotes the chemical reduction process of graphene oxide and benefits to repair the crystal defects. Due to the adsorption of β-Lactoglobulin on the surface of graphene sheets, the BLG-RGO composite was further used as template for Au nanoparticles assembly. These Au nanoparticles assembled on the BLG-RGO composite were shown to yield a large SERS enhancement for Rhodamine 6G.Keywords: Au nanoparticles; composite; pH-sensitive solubility; reduced graphene oxide; SERS; β-lactoglobulin;
Co-reporter:Deping Huang, Yuanyuan Qi, Xiangtao Bai, Lijuan Shi, Han Jia, Dongju Zhang, and Liqiang Zheng
ACS Applied Materials & Interfaces 2012 Volume 4(Issue 9) pp:4665
Publication Date(Web):August 9, 2012
DOI:10.1021/am301040b
Hierarchical, three-fold symmetrical dendritic gold was prepared in an aqueous solution of the quaternary ammonium cationic surfactant dodecyltrimethylammonium bromide (DTAB). Similar surfactants with different head groups and hydrocarbon chain lengths were also used for comparison. Two-fold and one-fold symmetrical dendritic gold nanostructures were obtained in N-dodecyl-N-methylpyrrolidinium bromide (C12-MPB) and dodecyltriethylammonium bromide (DTEAB) aqueous solutions, respectively. Longer hydrocarbon chain lengths were unfavorable for the formation of dendritic nanostructures. The interaction energies between the individual surfactants and Au (111) plane were calculated using molecular dynamics simulations. Based on a series of contrast experiments and molecular dynamics simulations, the possible growth mechanism and fabrication process of the dendritic structures were proposed. The DTAB-capped, three-fold gold dendrites exhibited good surface-enhanced Raman scattering (SERS) sensitivity toward rhodamine 6G (R6G), indicating their potential for use in SERS-based detections and analysis. This work provides a simple and effective strategy for fabricating dendritic gold nanostructures in aqueous solutions.Keywords: ammonium cationic surfactant; dendritic gold nanostructures; DTAB; head groups; hydrocarbon chain length; SERS;
Co-reporter:Han Jia, Xinpei Gao, Zhaolong Chen, Guoqiang Liu, Xiao Zhang, Hui Yan, Hongtao Zhou and Liqiang Zheng
CrystEngComm 2012 vol. 14(Issue 22) pp:7600-7606
Publication Date(Web):12 Jul 2012
DOI:10.1039/C2CE25840D
We report a facile, green, and high yielding approach for the synthesis and stabilization of relatively monodisperse gold nanoparticles using typical nonionic biosurfactant ethoxylated sterol (BPS-30). The obtained gold nanoparticles capped by BPS-30 not only showed remarkable stability after several months of storage under ambient conditions, but also exhibited exciting stability in high concentrations of electrolyte aqueous solutions such as acid, base, salt, and even physiological phosphate buffered saline (PBS). Derjaguin–Landau–Verwey–Overbeek (DLVO) theory was introduced to interpret the relationship between the capping mechanism and the excellent stability of the nanoparticles. UV-vis absorption spectroscopy was used to determine the yield of the gold nanoparticles. Moreover, the catalytic efficiency of the gold nanoparticles was evaluated by using the reduction of 4-nitroaniline by potassium borohydride in aqueous solution.
Co-reporter:Han Jia, Xiangtao Bai and Liqiang Zheng
CrystEngComm 2012 vol. 14(Issue 8) pp:2920-2925
Publication Date(Web):17 Feb 2012
DOI:10.1039/C2CE06375A
Gold nanochains were prepared at the air/water interface under the Langmuir monolayer of a long-chain ionic liquid 1-hexadecyl-3-methylimidazolium bromide (C16mimBr) through the reduction of AuCl4− ions by UV-light irradiation. It is revealed that these nanochains are self-assembled from gold nanoparticles about an average diameter of 15 nm. The synthesis and assembly of the Au nanoparticles can be achieved in one step. It is found that the structures of the nanochains are mainly dependent on reaction temperature. Both the π–π interactions and the steric hindrance play important roles in the formations of the nanochains. The application of the thin film of Au nanochains as a substrate for surface-enhanced Raman scattering (SERS) was demonstrated. Interestingly, the enhancement property depended on the temperature. This means the effective “hot spot” of the metal nanochains are dependent on their lengths, which may be controlled by the temperature.
Co-reporter:Jun Li, Mingwei Zhao, Hongtao Zhou, Hejun Gao and Liqiang Zheng
Soft Matter 2012 vol. 8(Issue 30) pp:7858-7864
Publication Date(Web):28 Jun 2012
DOI:10.1039/C2SM25218J
A photo-responsive system composed of an imidazolium-type surfactant 1-hexadecyl-3-methylimidazolium bromide ([C16mim]Br) and a commonly photosensitive aromatic compound trans-cinnamic acid (trans-CA) was studied through UV spectra, 1H NMR, and rheological measurements. In aqueous solution, the compounds [C16mim]Br and trans-CA can self-assemble to form viscoelastic wormlike micelles. Through UV irradiation, the CA molecules exhibit molecular photoisomerization from trans- to cis-, which results in a change of the molecular critical packing. The wormlike micelles transform into spherical micelles after UV irradiation, which is also confirmed by rheological measurements.
Co-reporter:Lijuan Shi, Mingwei Zhao and Liqiang Zheng
RSC Advances 2012 vol. 2(Issue 31) pp:11922-11929
Publication Date(Web):05 Oct 2012
DOI:10.1039/C2RA21467A
The phase behavior of ternary systems involving long-chain pyrrolidinium ionic liquids, N-alkyl-N-methylpyrrolidinium bromide (CnMPB, n = 12, 14, 16), water, and 1-decanol was investigated at 25 °C. Polarized optical microscopy (POM), small-angle X-ray scattering (SAXS), and rheological measurements were employed to investigate the lyotropic liquid crystalline (LC) phases. Lamellar phase (Lα) and hexagonal phase (H1) were found to exist in all the three systems, but the isotropic cubic phase only appears in the C12MPB and C14MPB systems. Greater surfactant content leads to a denser aggregation of the cylindrical units in the H1 phase, and the structural parameters of Lα phase depends on water content. The alkyl chain length of CnMPB also has interesting effect on the structural parameters and rheological properties of the LC phase. Compared with a similar ternary system of 1-hexadecyl-3-methylimidazolium chloride ([C16mim]Cl) and traditional cationic surfactants cetyltrimethylammonium bromide (C16TAB), the effect of the cationic group on the phase behavior was also investigated.
Co-reporter:Hongchao Ma, Xiangtao Bai, Liqiang Zheng
Materials Letters 2012 Volume 66(Issue 1) pp:212-215
Publication Date(Web):1 January 2012
DOI:10.1016/j.matlet.2011.08.091
Dumbbell-like CdTe/Au nanohybrids were synthesized by assembly of CdTe quantum dots with the assistance of AuCl4− in aqueous solution. The products were characterized by TEM and SEM techniques. The images reveal that dumbbell-like nanostructures with uniform size were well formed. The dumbbell-like nanostructures were further characterized by HRTEM and EDX spectrum. The results indicate that the as-prepared dumbbell-like nanostructures were composed of CdTe quantum dots and Au nanoparticles. The effect of HAuCl4 concentration on the morphology of the products was also investigated, which shows that the morphology of the products evolved from sheaf-like nanostructures to rod-like nanostructures and finally dumbbell-like nanostructures as the HAuCl4 concentration increased. Based on the above results, a possible mechanism for the formation of dumbbell-like CdTe/Au nanohybrids is proposed.Highlights► Dumbbell-like CdTe/Au nanohybrids were prepared. ► The dumbbell-like nanohybrids have rough surface. ► The nanohybrids could be used in photocatalysis and photoconducting devices.
Co-reporter:Xiu Jie Yang, Xin Ping Li, Xiang Tao Bai, Li Qiang Zheng
Chinese Chemical Letters 2012 Volume 23(Issue 9) pp:1091-1094
Publication Date(Web):September 2012
DOI:10.1016/j.cclet.2012.06.021
Uniform CdS colloidal spheres have been successfully synthesized via a simple hydrothermal method. X-ray diffraction (XRD) analyses indicate that the products exhibit a hexagonal structure. Scanning electron (SEM) and transmission electron microscopy (TEM) are used to characterize CdS colloidal spheres. The final size of the spheres may be selected from a range of 71 ± 2 nm to approximately 181 ± 5 nm by changing the amount of polyvinylpyrrolidone (PVP) and hexamethylenetetramine (HMT). The CdS colloidal spheres are not obtained in the absence of either of the capping agents. A synergistic effect between HMT and PVP is proposed to be crucial for the formation of colloidal spheres.
Co-reporter:Jun Li, Mingwei Zhao, Liqiang Zheng
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2012 Volume 396() pp:16-21
Publication Date(Web):20 February 2012
DOI:10.1016/j.colsurfa.2011.12.019
The wormlike micelles formed by surface active N-alkyl-N-methylpyrrolidinium bromide ionic liquids (ILs) have been investigated in aqueous solution. The typical rheological parameters and the viscoelastic properties of wormlike micelles were characterized by rheological measurements and cryogenic-transmission electron microscopy (cryo-TEM). The typical rheological parameters were further evaluated by Maxwell model and the viscoelastic properties were discussed based on the living polymer model. Cryo-TEM images confirmed the formation of wormlike micelles in aqueous solution. The effect of the hydrocarbon chain length of the ILs on the wormlike micelles formation was also studied.Graphical abstractThe wormlike micelles formed by C16MPB in aqueous solutions was investigated by rheological and cryo-TEM.Highlights► Methylpyrrolidium ionic liquid are formed wormlike micelles by salt induced in aqueous solution. ► The strong hydrophobic interactions are necessary to form the wormlike micelles in the system. ► The cryo-TEM image shows the long entangled wormlike micelles and branched micelles.
Co-reporter:Hejun Gao;Shaohua Zhang;Deping Huang
Colloid and Polymer Science 2012 Volume 290( Issue 8) pp:757-762
Publication Date(Web):2012 June
DOI:10.1007/s00396-012-2619-9
Multi-wall carbon nanotubes (MWCNTs) can be effectively dispersed by an ionic liquid-based polyether, poly(1-glycidyl-3-methylimidazolium chloride) (PGMIC) in aqueous solution. The amount of dispersed MWCNTs increases with the increasing of PGMIC concentration, and then decreases. Reaggregation of MWCNTs is observed when PGMIC exceeded the optimal concentration, which may be due to the conformational change of PGMIC molecules around MWCNT. The ultrasonic dispersion method is better than stirring method in the PGMIC solution. Furthermore, the acidic solution is convenient to prepare stable MWCNTs suspensions. Through the characterizations of ultraviolet–visible–near infrared, thermogravimetric analysis and Fourier transform infrared, it can be concluded that electrostatic repulsions, hydrophobic effect, n–π, and cation–π interactions played important roles in the dispersion of MWCNTs.
Co-reporter:Shaohua Zhang;Jie Liu;Na Li;Xiujie Yang
Colloid and Polymer Science 2012 Volume 290( Issue 18) pp:1927-1935
Publication Date(Web):2012 December
DOI:10.1007/s00396-012-2733-8
The aggregation behavior of two silicone surfactants (monomeric and Gemini) was studied by surface tension measurements in a room temperature ionic liquid, ethylammonium nitrate (EAN), at various temperatures. A series of parameters, including critical micelle concentration (CMC), surface tension at the CMC (γCMC), adsorption efficiency (pC20), and effectiveness of surface tension reduction (ΠCMC), were obtained. By comparing the silicone surfactants with traditional surfactants, we deduced that the surface activity of the silicone surfactants in EAN was superior to the activity of other surfactants. In addition, from the CMC values and their temperature dependence, we estimated the thermodynamic parameters of the micelle formation, \( \Delta G_m^0 \), \( \Delta H_m^0 \), and \( \Delta S_m^0 \). It was revealed that the micellization of the silicone surfactants is entropy driven at low temperature and enthalpy driven at high temperature. Isothermal titration calorimetry measurements were also carried out to study the micellization of Gemini silicone surfactant. 1H NMR was performed to study the silicone surfactant micelle formation mechanism in EAN.
Co-reporter:Mingwei Zhao;Jie Yuan
Colloid and Polymer Science 2012 Volume 290( Issue 14) pp:1361-1369
Publication Date(Web):2012 September
DOI:10.1007/s00396-012-2664-4
The phase behavior of the mixed catanionic surfactants in aqueous solution, composed of the long-chain ionic liquid (IL) N-dodecyl-N-methylpyrrolidinium (C12MPB) and a divalent metal surfactant copper dodecyl sulfate (Cu(DS)2·4H2O), was investigated. The phase diagram of the catanionic system was mapped through visual observation and electrical conductivity measurement. The formation of vesicles was confirmed in the lamellar phase (Lα) through transmission electron microscopy (TEM). Rheological measurements were used to study the macroscopic properties of the birefringent Lα phase. Electrostatic and hydrophobic interactions are regarded as the main driving forces for the formation of vesicles. Furthermore, the vesicles were successfully used as the templates to prepare the leaflike CuO nanomaterials.
Co-reporter:Hejun Gao;Shaohua Zhang;Fei Lu;Han Jia
Colloid and Polymer Science 2012 Volume 290( Issue 17) pp:1785-1791
Publication Date(Web):2012 November
DOI:10.1007/s00396-012-2720-0
Graphene sheets can be effectively dispersed by a novel ionic liquid-based polyether, poly(1-glycidyl-3-methylimidazolium chloride) (PGMIC), in aqueous solution. The reduction of graphene oxide to graphene is confirmed by UV–Vis and Raman spectrum in aqueous solution of PGMIC. TEM image showed that the stable and uniform dispersion of graphene sheets were obtained. Both the TGA and AFM analysis indicated that the graphene sheet was covered by PGMIC. FTIR spectra demonstrated that n–π, cation–π interactions and electrostatic repulsions played important roles in the dispersion of graphene sheets.
Co-reporter:Jie Liu;Qian Zhang;Yu Huo;Mingwei Zhao;Dezhi Sun
Colloid and Polymer Science 2012 Volume 290( Issue 17) pp:1721-1730
Publication Date(Web):2012 November
DOI:10.1007/s00396-012-2690-2
In the preceding paper of this series, we studied the interactions of copolymers with the ionic liquids, 1-alkyl-3-methylimidazolium bromide (CnmimBr, n = 8, 10, 12, 14, 16) and N-alkyl-N-methylpyrrolidinium bromide (CnMPB, n = 12, 14, 16). An obvious difference was detected between the interaction mechanism and the alkyl chain length of the surfactant. In the present study, we performed a systematic study on the interaction of sodium carboxymethylcellulose (NaCMC) with ionic liquids in aqueous solution by isothermal titration microcalorimetry (ITC), conductivity, turbidity, and dynamic light scattering (DLS) measurements. The existence of electrostatic attraction between NaCMC and ILs could increase the complexity of these systems. The results show that the monomers of C8mimBr can bind to the NaCMC chains and form free surfactant micelles in the solution, while no micelle-like C8mimBr/NaCMC cluster is detected. For other surfactants, the formation of surfactant/NaCMC clusters in the solution is driven by electrostatic and hydrophobic interactions, which could be divided into two types. One type is the polymer-induced surfactant/NaCMC complexes that form in the solution for the surfactant of CnmimBr (n = 10, 12, 14) or CnMPB (n = 12, 14). The other type is that the surfactant-induced surfactant/NaCMC complexes come into being for the surfactant of C16mimBr or C16MPB. Finally, the different modes of complex formation proposed have a good interpretation of the experiment results, unraveling the details of the effect of surfactant alkyl chain length and headgroup on the surfactant–NaCMC interactions.
Co-reporter:Lijuan Shi and Liqiang Zheng
The Journal of Physical Chemistry B 2012 Volume 116(Issue 7) pp:2162-2172
Publication Date(Web):January 23, 2012
DOI:10.1021/jp211338k
The aggregation behavior of surface active imidazolium ionic liquids (ILs) with different alkyl chain length, cations, and counterions, namely, 1-alkyl-3-methylimidazolium bromide ([Cnmim]Br (n = 8, 10, 12)), 1-dodecyl-2,3-dimethylimidazolium bromide ([C12bmim]Br), 1-(2,4,6-trimethylphenyl)-3-dodecylimidazolium bromide ([C12pim]Br), and 1-dodecyl-3-methylimidazolium tetrafluoroborate ([C12mim][BF4]) in a protic room temperature IL, ethylammonium nitrate (EAN), was investigated through surface tension measurements and 1H NMR spectroscopy. Surface tension results show that surface properties and micellization behavior of surface active ILs in EAN are significantly affected by the structure of the cations, the basicity of counterions, and the hydrophobicity of alkyl chains. A detailed analysis of chemical shifts of various protons of surface active ILs and EAN was employed to investigate the micelle formation mechanism. Hydrogen bonding interaction is found to occur between the protons at C-2 on the imidazolium ring and the oxygen atoms in [NO3]− anions, and the interaction varies as a function of the basicity of the counterions and the hydrophobicity of the side-chains bonded to the imidizolium ring. The micelle formation may be accompanied by a partial changeover from trans to gauche conformations in the alkyl chain. The solvophobic effect may exist between the hydrophobic portion of [CH3CH2NH3]+ and the hydrophobic chains of the surface active ILs.
Co-reporter:Fei Lu, Shaohua Zhang, Liqiang Zheng
Journal of Molecular Liquids 2012 173() pp: 42-46
Publication Date(Web):
DOI:10.1016/j.molliq.2012.06.012
Co-reporter:Mingwei Zhao, Jie Yuan, Liqiang Zheng
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2012 Volume 407() pp:116-120
Publication Date(Web):5 August 2012
DOI:10.1016/j.colsurfa.2012.05.016
The spontaneous formation of vesicles in an aqueous catanionic mixture, composed of a cationic surface active long-chain ionic liquid N-dodecyl-N-methylpyrrolidinium bromide (C12MPB) and an anionic surfactant sodium dodecyl sulfate (SDS), is investigated. The phase behavior of catanionic system is studied and the phase diagram is mapped through visual observation and electrical conductivity measurement. The vesicles formed in the lamellar phase (Lα) are characterized by transmission electron microscopy (TEM). The macroscopic properties of birefringent Lα phase are investigated by rheological measurements. The hydrophobic and electrostatic interactions are regarded as the main driving forces for spontaneous formation of vesicles.Graphical abstractThe spontaneous formation of vesicles in the aqueous catanionic mixture, composed of a cationic surface active long-chain ionic liquid N-dodecyl-N-methylpyrrolidinium bromide (C12MPB) and an anionic surfactant sodium dodecyl sulfate (SDS), is investigated through visual observation, electrical conductivity measurement, transmission electron microscopy (TEM), and rheological measurements.Highlights► The spontaneous formation of vesicles was studied in the aqueous catanionic mixture of N-dodecyl-N-methylpyrrolidinium bromide (C12MPB) and sodium dodecyl sulfate (SDS). ► The TEM image confirmed the formation of vesicles. ► The hydrophobic and electrostatic interactions are regarded as the main driving forces.
Co-reporter:Han Jia, Xiangtao Bai, Na Li, Li Yu and Liqiang Zheng
CrystEngComm 2011 vol. 13(Issue 20) pp:6179-6184
Publication Date(Web):17 Aug 2011
DOI:10.1039/C1CE05715D
A siloxane surfactant was used for the mild synthesis and simultaneous 1D assembly of gold nanoparticles. The length of the gold nanochains could be tuned by facile adjustment of the surfactant concentration. The multiple interactions between the siloxane surfactant and gold nanoparticles made the non-uniform spatial distribution of stabilizers at the nanoparticle surfaces and then led to the 1D assembly. Transmission electron microscopy (TEM) and UV-vis spectroscopy have been employed for characterizing the nanochains. The effect of ionic strength in the spontaneous linear assembly of gold nanoparticles was investigated to further elucidate the assembly of mechanism. These gold nanochains were shown to yield a large SERS enhancement for Rhodamine 6G.
Co-reporter:Mingwei Zhao and Liqiang Zheng
Physical Chemistry Chemical Physics 2011 vol. 13(Issue 4) pp:1332-1337
Publication Date(Web):23 Nov 2010
DOI:10.1039/C0CP00342E
The micellization of the ionic liquid N-alkyl-N-methylpyrrolidinium bromide (CnMPB, n = 12, 14 and 16) in aqueous solutions was investigated by surface tension measurements, electrical conductivity and static luminescence quenching. The effectiveness of the surface tension reduction (Πcmc), maximum surface excess concentration (Γmax) and the minimum area (Amin) occupied per surfactant molecule at the air/water interface can be obtained from the surface tension measurements at 25 °C. The critical micelle concentration (cmc) at different temperatures and a series of thermodynamic parameters (ΔG0m, ΔH0m and ΔS0m) of micellization were evaluated from electrical conductivity measurements in the temperature range of 25–45 °C. The thermodynamic parameters show that the micelle formation is entropy-driven at low temperature and enthalpy-driven at high temperature. Furthermore, the micelle aggregation number (Nagg) of CnMPB was calculated according to the Turro-Yekta method through static luminescence quenching and found that Nagg (49, 55, and 59) increased with the hydrophobic chain length of CnMPB.
Co-reporter:Han Jia, Xiangtao Bai and Liqiang Zheng
CrystEngComm 2011 vol. 13(Issue 24) pp:7252-7257
Publication Date(Web):30 Sep 2011
DOI:10.1039/C1CE05835E
A facile and effective method to synthesize dendrite-shaped calcium carbonate (CaCO3) nanocrystals in aqueous solutions of dodecyltrimethylammonium bromide (DTAB) and β-cyclodextrin (β-CD) is reported. It has been demonstrated that the supramolecular host–guest complexes formed by DTAB and β-CD play a key role in the fabrication of these unique CaCO3 nanocrystals. In order to systematically study the effect of the cationic surfactant, 1-dodecyl-3-methylimidazolium bromide (C12mimBr) and didodecyltrimethylammonium bromide (DDAB) were also used. The results show that the structures of the complexes formed by different cationic surfactants with β-CD have a strong impact on the final morphologies of the CaCO3 nanocrystals. Moreover, the interaction energies between β-CD and cationic surfactant molecules were calculated using molecular mechanics, and a possible mechanism for the formation of CaCO3 nanocrystals was proposed.
Co-reporter:Hongchao Ma, Xiangtao Bai and Liqiang Zheng
CrystEngComm 2011 vol. 13(Issue 11) pp:3788-3793
Publication Date(Web):31 Mar 2011
DOI:10.1039/C1CE05086A
In the present work, urchin-like CdTe microspheres were prepared through the self-assembly of CdTe quantum dots (QDs) via the monolayer of a long-chain ionic liquid, 1-hexadecyl-3-methylimidazolium bromide (C16mimBr). The TEM and SEM images indicated that the synthesized urchin-like microspheres were about 2.0 μm in diameter and composed of nanorods grown on their surfaces. The effects of the growth time and the concentration of CdTe QDs were investigated, and the results revealed that sufficient growth time and appropriate concentration were both required for the formation of the urchin-like CdTe microspheres. Based on these results, a possible mechanism for the formation of the urchin-like CdTe microspheres is proposed.
Co-reporter:Xiangtao Bai, Yanan Gao and Liqiang Zheng
CrystEngComm 2011 vol. 13(Issue 10) pp:3562-3568
Publication Date(Web):18 Mar 2011
DOI:10.1039/C1CE05084B
Hierarchical, three-fold symmetrical, single-crystalline gold dendrites are synthesized on different metal substrates including Al, Zn, and Ni in a mixture of ethanol and water with the assistance of an ionic liquid. Structural characterizations suggest that the obtained gold dendrites are grown along the <211> directions. Such <211>-oriented gold dendrites are seldom reported. Both the metal substrate and the volume ratio of ethanol and water have demonstrated a significant effect on the dendrite morphologies. The obtained gold dendrites are found to yield large SERS enhancement factors for rhodamine 6G (R6G) and the morphology of the branches is a key for the enhancement.
Co-reporter:Bin Dong, Yijin Su, Yonghui Liu, Jie Yuan, Jingkun Xu, Liqiang Zheng
Journal of Colloid and Interface Science 2011 Volume 356(Issue 1) pp:190-195
Publication Date(Web):1 April 2011
DOI:10.1016/j.jcis.2010.12.080
Surfactants with a polycyclic aromatic moiety and a long hydrocarbon chain, carbazole-tailed amphiphilic imidazolium ionic liquids 1-[n-(N-carbazole)alkyl]-3-methylimidazolium bromide [CzCnMIm]Br (n = 10 and 12), were designed to disperse carbon nanotubes (CNTs) in aqueous solutions. UV–vis–NIR spectra were performed to determine the dispersion of CNTs and the optimal concentration (Copt) of [CzCnMIm]Br. Compared with [CnMIm]Br, [CzCnMIm]Br was more effective with the smaller Copt and more individual CNTs, reflecting the effect of the carbazole moiety. The adsorption of [CzCnMIm]Br molecules on CNTs was investigated by zeta-potential, surface tension, fluorescence, and 1H NMR. Having zeta-potentials higher than 15 mV contributed to the long-term stability of aqueous CNT dispersions. The significant fluorescence quenching and the upfield shift of carbazole protons support the π–π stacking interaction between carbazole moieties and the π-networks of CNTs. Meanwhile, the upfield shift of imidazolium protons indicates the cation–π interaction between the imidazolium ions and the π-networks of CNTs.Graphical abstractCNTs were dispersed in water using a surface-active ionic liquid with a polycyclic aromatic moiety and a long hydrophobic chain.Research highlights► Surfactants enhanced the solubilization of CNTs in water. ► Polycyclic compounds enhanced the solubilization of CNTs in water. ► [CzCnMIm]Br contains a polycyclic aromatic moiety and a long hydrophobic chain. ► [CzCnMIm]Br shows a strong ability to disperse CNTs in water.
Co-reporter:Jie Liu;Mingwei Zhao;Qian Zhang;Dezhi Sun;Xilian Wei
Colloid and Polymer Science 2011 Volume 289( Issue 15-16) pp:1711-1718
Publication Date(Web):2011 October
DOI:10.1007/s00396-011-2492-y
The interaction of nonionic triblock copolymers of poly(ethyleneoxide) (PEO) and poly(propyleneoxide) (PPO) (PEOnPPOmPEOn) with a series of cationic surface-active ionic liquids in aqueous solutions have been investigated. The cationic surface-active ionic liquids include 1-alkyl-3-methylimidazolium bromide (CnmimBr, n = 8, 10, 12, 14, 16) and N-alkyl-N-methylpyrrolidinium bromide (CnMPB, n = 12, 14, 16). For different polymer-surfactant systems, the critical aggregation surfactant concentration (cac), the surfactant concentration to form free micelles (Cm), and the saturation concentration of surfactant on the polymer chains (C2) were determined using isothermal titration microcalorimetry (ITC) and conductivity measurements. The structure of the formed aggregates depended strongly on the hydrophobicity of the surfactant and the ratio of polymer/surfactant concentration. For C8mimBr, there were not any micelle-like surfactant–polymer clusters detected in the solution, and only micelles appeared. For other surfactants, the polymer–surfactant aggregates were formed in the solution, which was verified by the appearance of a broad endothermic peak in the ITC thermograms. The intensity of polymer–surfactant interaction increased with the hydrophobicity of the surfactants and the polymers but was not affected by the surfactant headgroups.
Co-reporter:Han Jia, Xiangtao Bai, Liqiang Zheng
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2011 Volume 384(1–3) pp:75-79
Publication Date(Web):5 July 2011
DOI:10.1016/j.colsurfa.2011.03.007
Ribbon-like, wedge-shaped, and spherical gold nanostructures were prepared via a novel two-step growth method. Various gold nanostructures were first pre-formed in aqueous solution by using β-cyclodextrin (β-CD) as both reducing and capping agent. Due to the continuous growth of the pre-formed gold nanostructures at the air/water interface with the help of the Langmuir monolayers of 1-hexadecyl-3-methylimidazolium bromide (C16mimBr), morphology changes can be observed obviously. The gold nanostructures were characterized by transmission electron microscopy (TEM) and UV–vis spectroscopy. A possible mechanism based on the interaction between β-CD and the pre-formed gold nanostructures is proposed.Graphical abstractGold nanostructures of various morphologies were prepared via a two-step growth method. Controlled synthesis of gold nanostructures in aqueous solution was realized by varying the ratios of β-CD-to-HAuCl4, and the β-CD was as both reducing and capping agent. Through their continuous growth with the aid of Langmuir monolayers, ribbon-like, wedge-shaped and spherical gold nanostructures were obtained.Highlights► Seed-mediated growth and Langmuir–Blodgett technique are combined to prepare the gold nanostructures. ► Various gold nanostructures were first pre-formed in aqueous solution by varying the ratio β-CD-to-HAuCl4. ► A delicate adsorbing equilibrium caused by the variety of molar ratios of β-CD-to-HAuCl4 plays a key role in the continuous growth at the air/water interface.
Co-reporter:Han Yan, Mingwei Zhao, Liqiang Zheng
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2011 Volume 392(Issue 1) pp:205-212
Publication Date(Web):5 December 2011
DOI:10.1016/j.colsurfa.2011.09.057
A novel hydrogel constructed by N-methyl-N-cetylpyrrolidinium bromide (C16MPBr) and sodium salicylate (NaSal) is investigated using 1H NMR, FT-IR, SEM, and rheological measurements. Through the rheological characterization of the hydrogels, both the NaSal concentration and pH have significant effects on the formation and properties of the gels. 1H NMR, FT-IR, and SEM have also been employed to investigate the molecular arrangement and morphology of the gels. Hydrophobic and electrostatic interactions are considered as the main driving forces to form the gels.Graphical abstractA novel hydrogel constructed by N-methyl-N-cetylpyrrolidinium bromide (C16MPBr) and sodium salicylate (NaSal) is investigated using 1H NMR, FT-IR, SEM, and rheological measurements.Highlights► A hydrogel formed by C16MPBr and NaSal is investigated. ► The gel formation process undergoes a transition from wormlike micelles to gels. ► Both salt concentration and pH have effects on the properties of the gels. ► Hydrophobic and electrostatic interactions are driving forces to form the gels.
Co-reporter:Lijuan Shi, Mingwei Zhao, Liqiang Zheng
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2011 Volume 392(Issue 1) pp:305-312
Publication Date(Web):5 December 2011
DOI:10.1016/j.colsurfa.2011.09.064
The aggregation behavior of long-chain pyrrolidinium ionic liquids, N-alkyl-N-methylpyrrolidinium bromide (CnMPB, n = 12, 14, and 16) was investigated by surface tension measurements in a protic room temperature ionic liquid, ethylammonium nitrate (EAN), at various temperatures. A series of parameters, including critical micelle concentration (CMC), surface tension at the CMC (γCMC), effectiveness of surface tension reduction (ΠCMC), maximum surface excess concentration (Γmax), and the area occupied per surfactant molecule at the air/solution interface (Amin) were estimated. From these parameters, we demonstrated that the surface activity of CnMPB is much lower in EAN than that in water. Comparing CnMPB with alkylimidazolium bromides and alkylpyridinium bromides, the effect of the cationic group on micellization in EAN was also investigated. The thermodynamic analysis of micellization revealed that the micelle formation process for CnMPB (n = 12, 14, and 16) is entropy-driven at low temperature and enthalpy-driven at high temperature. The micelle aggregation number estimated from the 1H NMR data is about 21 for C12MPB in EAN, which is much less than that in water. The results of the surface tension measurements and 1H NMR spectra indicate that the [CH3CH2NH3]+ cations of EAN exist around the head groups of CnMPB when micelles are formed and the NO3− ions are adsorbed at the micelle surface.Graphical abstractThe aggregation behavior of long-chain pyrrolidinium ionic liquids, N-alkyl-N-methylpyrrolidinium bromide (CnMPB, n = 12, 14, and 16) was investigated by surface tension measurements in a protic room temperature ionic liquid, ethylammonium nitrate (EAN), at various temperatures.Highlights► The micellization of N-alkyl-N-methylpyrrolidinium bromide in EAN was investigated. ► The surface activity of CnMPB in EAN is much lower than that in water. ► The CMC for CnMPB is much lower than CnmimBr. ► The thermodynamic parameters of the micelle formation were estimated. ► [CH3CH2NH3]+ cations and NO3− ions of EAN exist around the micelle surface.
Co-reporter:Lijuan Shi, Na Li, Han Yan, Yan’an Gao, and Liqiang Zheng
Langmuir 2011 Volume 27(Issue 5) pp:1618-1625
Publication Date(Web):January 19, 2011
DOI:10.1021/la104719v
The aggregation behavior of three long-chain N-aryl imidazolium ionic liquids (ILs), 1-(2,4,6-trimethylphenyl)-3-alkylimidazolium bromide [Cnpim]Br (n = 10, 12, and 14), in aqueous solutions was systematically explored by surface tension, electrical conductivity, and 1H NMR. A lower critical micelle concentration (cmc) for the N-aryl imidazolium ILs is observed compared with that for 1,3-dialkylimidazolium ILs [Cnmim]Br, indicating that the incorporation of the 2,4,6-trimethylphenyl group into a headgroup favors micellization. The enhanced π−π interactions among the adjacent 2,4,6-trimethylphenyl groups weaken the steric hindrance of headgroups and thus lead to a dense arrangement of [Cnpim]Br molecules at the air−water interface. An analysis of the 1H NMR spectra revealed that the introduced 2,4,6-trimethylphenyl group may slightly bend into the hydrophobic regions upon micellization. The micelle formation process for [Cnpim]Br (n = 10, 12, and 14) was found to be enthalpy-driven in the investigated temperature range, which is attributed to the strong electrostatic self-repulsion of the headgroups and the counterions as well as the π−π interactions among headgroups. Strong, stable fluorescence properties are presented by the new N-aryl imidazolium ILs, indicating their potential application in the field of photochemistry.
Co-reporter:Shaohua Zhang;Fei Lu
Colloid and Polymer Science 2011 Volume 289( Issue 17-18) pp:1815-1819
Publication Date(Web):2011 November
DOI:10.1007/s00396-011-2500-2
Gemini pyrrolidinium surfactants ([Cnpy-4-Cnpy][Br2]) are a new kind of ionic liquid-based Gemini surfactants. Multiwalled carbon nanotubes (MWCNTs) can be dispersed effectively in [Cnpy-4-Cnpy][Br2] aqueous solution. The resulting MWCNT suspensions are stable for more than 1 month, and no precipitation is observed. Ultraviolet–visible–near infrared (UV–Vis–NIR) spectra are performed to determine the dispersion of MWCNTs and the optimal concentration (Copt) of [Cnpy-4-Cnpy][Br2]. Compared with CnMPB, [Cnpy-4-Cnpy][Br2] is more effective in dispersing MWCNTs. It was also observed that [Cnpy-4-Cnpy][Br2] with a longer hydrocarbon chain displays a stronger dispersion ability. The adsorption of [Cnpy-4-Cnpy][Br2] on MWCNTs is investigated by zeta-potential and surface tension measurements. The zeta-potential results show that MWCNTs dispersed in [Cnpy-4-Cnpy][Br2] aqueous solution have relatively high positive charges. It is the electrostatic repulsion force between the MWCNTs which makes them stable. Furthermore, a possible dispersion mechanism is proposed.
Co-reporter:Deping Huang, Xiangtao Bai, and Liqiang Zheng
The Journal of Physical Chemistry C 2011 Volume 115(Issue 30) pp:14641-14647
Publication Date(Web):July 5, 2011
DOI:10.1021/jp2037284
Three-dimensional dendritic gold nanostructures were prepared via an ultrafast one-step homogeneous solution method. Cationic surfactants, decane-1,10-bis(methylpyrrolidinium bromide) ([mpy-C10-mpy]Br2), were used as the capping agent and l-ascorbic acid (AA) was used as the reducing agent. The as-prepared gold dendrites present a [111] plane and grow along the ⟨211⟩ direction. The AA plays an important role in the formation of the dendritic nanostructures. The methylpyrrolidinium quaternary ammonium headgroups and bolaform nanostructures of the surfactants are the key factors for the formation of dendritic structures. Further investigation revealed that the reaction time and concentration of HAuCl4 weakly affect the formation of the dendrites. Moreover, the obtained gold dendrites exhibit excellent activity toward the catalytic reduction of p-nitraniline and higher enhancement of surface-enhanced Raman scattering when using Rhodamine 6G as the model molecules.
Co-reporter:Lijuan Shi ; Na Li
The Journal of Physical Chemistry C 2011 Volume 115(Issue 37) pp:18295-18301
Publication Date(Web):August 16, 2011
DOI:10.1021/jp206325d
The aggregation behavior of long-chain N-aryl imidazolium ionic liquids (ILs), 1-(2,4,6-trimethylphenyl)-3-alkylimidazolium bromide [Cnpim]Br (n = 10, 12, 14), was investigated in a room temperature IL, 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) by surface tension measurements. Freeze-fracture transmission electron microscopy (FF-TEM) and dynamic light scattering (DLS) measurements further verified that micelles are formed. A relatively lower critical micelle concentration (CMC) and smaller micelle size were observed compared with that of N-alkylimidazolium ILs [Cnmim]Br. The main reason for this phenomenon is that the electrostatic repulsion between the head groups of [Cnpim]Br is weakened due to the incorporation of the 2,4,6-trimethylphenyl group. The thermodynamic parameters of micelle formation of [Cnpim]Br in [bmim][BF4] were estimated from the CMC values and their temperature dependence. The micelle formation process is enthalpy-driven in the investigated temperature range, similar to the case in water. The novel N-aryl imidazolium ILs present strong fluorescence properties in [bmim][BF4], indicating their potential application in the field of photochemistry.
Co-reporter:Jie Liu, Bin Dong, Dezhi Sun, Xilian Wei, Suna Wang, Liqiang Zheng
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2011 380(1–3) pp: 308-313
Publication Date(Web):
DOI:10.1016/j.colsurfa.2011.03.019
Co-reporter:Shaohua Zhang;Jie Yuan;Hongchao Ma;Na Li
Colloid and Polymer Science 2011 Volume 289( Issue 2) pp:213-218
Publication Date(Web):2011 January
DOI:10.1007/s00396-010-2333-4
An aqueous phase behavior was investigated for ionic liquid-related cationic gemini surfactant, [C12im-4-C12im][Br2], in which two dodecylimidazolium parts are linked by a spacer composed of four methylene units. Differential scanning calorimetry was used to detect phase boundaries among various phases, from which a temperature−composition (T−X) phase diagram was constructed. Lyotropic liquid-crystalline phases appearing in this mixture were characterized by means of polarized optical microscopy. It was revealed that (1) two types of liquid-crystalline phases, lamellar (\( {{\hbox{L}}_\alpha } \)) and hexagonal (H1), are formed; (2) H1 phase coexists with micellar solution (L1) over a wide concentration range from a few wt.% to ca. 80 wt.% of the surfactant; and (3) the hydrated solid with the composition of [C12im-4-C12im][Br2]·2H2O exhibits incongruent melting point at which the hydrated solid decomposes into H1 phase and unhydrated surfactant solid.
Co-reporter:Xiangtao Bai and Liqiang Zheng
Crystal Growth & Design 2010 Volume 10(Issue 11) pp:4701-4705
Publication Date(Web):October 6, 2010
DOI:10.1021/cg101220v
Two-dimensional dendritic gold nanostructures are synthesized at the air/water interface with the assistance of a special additive, [camphorC2mim]Cl, which can form a precipitate with AuCl4−. Interestingly, the precipitate is essential to the formation of dendritic nanostructures. Transmission electron microscopy (TEM) characterization reveals that the ratio of [camphorC2mim]Cl to HAuCl4 rather than the concentration is crucial to the morphology of the obtained dendritic nanostructures. A reasonable mechanism based on diffusion-limited aggregation (DLA) theory is proposed according to the high resolution TEM (HRTEM) characterization. The obtained gold dendrites are shown to yield a large surface-enhanced Raman scattering (SERS) enhancement for rhodamine 6G.
Co-reporter:Guo-Li Li, Yan-An Gao, Xin-Wei Li, Jie Liu, Li-Qiang Zheng, Hang Xing, Jin-Xin Xiao
Journal of Colloid and Interface Science 2010 Volume 342(Issue 2) pp:372-381
Publication Date(Web):15 February 2010
DOI:10.1016/j.jcis.2009.10.058
N-alkyl perfluorooctanesulfonamides (C8F17SO2NHCnH2n+1, FC8HCn, n = 2, 4, 6, 8) were shown to form aggregates in dimethyl sulfoxide (DMSO). Surface tension results revealed that the dissolution of FC8HCn reduced the surface tension of DMSO in a manner analogous to common surfactants in aqueous solutions. Maximum surface excess amount (Γmax) and minimum surface area per molecule (Amin) at the air–liquid interface were estimated. Γmax decreases and Amin increases with an increase of the hydrocarbon chain length of FC8HCn. Steady-state fluorescence and NMR measurements demonstrated that both fluorocarbon and hydrocarbon chains of FC8HCn molecules were incorporated inside the aggregates. UV–vis spectroscopy confirmed the formation of aggregates and determined the critical micelle concentration (cmc) of FC8HC6 and FC8HC8 solutions. The thermodynamic parameters ΔGagg0, ΔHagg0, and ΔSagg0 for the aggregate formation of FC8HCn in DMSO derived from the temperature dependence of the cmc revealed that the aggregate formation is an enthalpy-driven process, which was further confirmed by isothermal titration calorimetry (ITC) measurements. Moreover, the absolute values of ΔGagg0 and ΔHagg0 increase with an increase of the hydrocarbon chain length of FC8HCn at 298 K.Aggregation behavior of N-alkyl perfluorooctanesulfonamides (FC8HCn, n = 2, 4, 6, 8) in dimethyl sulfoxide solutions were studied by surface tension measurements, FF-TEM, steady-state fluorescence, NMR and UV–vis spectroscopy.
Co-reporter:Xin-Wei Li, Yan-An Gao, Jie Liu, Li-Qiang Zheng, Bin Chen, Li-Zhu Wu, Chen-Ho Tung
Journal of Colloid and Interface Science 2010 Volume 343(Issue 1) pp:94-101
Publication Date(Web):1 March 2010
DOI:10.1016/j.jcis.2009.11.010
The synthesis of a chiral long-chain ionic liquid (IL), S-3-hexadecyl-1-(1-hydroxy-propan-2-yl)-imidazolium bromide ([C16hpim]Br), is presented. The adsorption and aggregation of this surface active IL in aqueous solution is described. The critical micelle concentration (cmc) measurement suggests that the chiral IL has superior capacity for micelle formation compared to traditional ionic surfactants. The relatively larger hydrophilic head group of the IL results in a larger maximum surface excess concentration (Γmax) and a smaller minimum molecular cross-sectional area (Amin). Electrical conductivity studies show a small degree of counterion binding to these micelles, which may increase the electrostatic repulsions between the hydrophilic heads of adjacent surfactant molecules. Both factors of the hydrophilic headgroup size and electrostatic repulsion in [C16hpim]Br micelles lead to a looser packing of the surfactant molecules in the micelles. As a result, a higher micropolarity and smaller mean aggregation number is observed. Moreover, the looser micellar packing of the [C16hpim]Br molecules results in a unusual upfield shift of the proton NMR signals in the hydrophobic chains after micelle formation. 1H NMR and 2D ROESY spectroscopic analyses confirm a chiral arrangement of the micelles. Chiral IL micelles may have potential applications in the stereochemical recognition of surfaces or of biological structures.Aggregation behavior of a surface active long-chain chiral ionic liquid, S-3-hexodecane-1-(1-hydroxy-propan-2-yl) imidazolium bromide, in aqueous solution are investigated.
Co-reporter:Mingwei Zhao;Yanan Gao, ;Wenpei Kang;Xiangtao Bai ;Bin Dong
European Journal of Inorganic Chemistry 2010 Volume 2010( Issue 6) pp:975-982
Publication Date(Web):
DOI:10.1002/ejic.200900737
Abstract
Hollow silica microspheres and hollow worm-like materials were synthesized by using a simple method with the aid of 1-dodecyl-3-methylimidazolium bromide (C12mimBr). Hollow silica microspheres were initially produced by utilizing the combination of evaporation and an emulsion template. At a longer mixing time, the microspheres fused to form hollow worm-like silica materials due to the fusion of the emulsion templates. The resultant silica materials were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and nitrogen adsorption/desorption. Both the hollow silica microspheres and the hollow worm-like materials are microporous. On the basis of experimental observations and the resulting products, a plausible formation mechanism is proposed. Preliminary tests demonstrate that the hollow silica microspheres and worm-like materials are capable of being loaded with Rhodamine B and releasing it, thus showing a great potential in controlled delivery applications.
Co-reporter:Hong Ying Wang, Yan An Gao, Ming Wei Zhao, Li Qiang Zheng
Chinese Chemical Letters 2010 Volume 21(Issue 7) pp:872-875
Publication Date(Web):July 2010
DOI:10.1016/j.cclet.2010.01.036
Silver nanorods have been successfully synthesized in large scale by the ethylene glycol (EG) reduction in the presence of ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4) and polyvinyl-pyrrolidone (PVP). The silver nanorods were characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), transmission electron microscopy (TEM), electron energy disperse spectroscopy (EDS) and UV–vis spectroscopy. The results showed that the uniform silver nanorods have an average diameter of about 100 nm and the aspect ratio from 15 to 20. IL, bmimBF4 may play a role of capping agent together with PVP in the formation of silver nanorods. On the other hand, bmimBF4 may accelerate nucleation and improve the stability of the resulting Ag nanorods due to the low interface tension of IL.
Co-reporter:Mingwei Zhao, Wenpei Kang, Liqiang Zheng, Yanan Gao
Materials Letters 2010 Volume 64(Issue 8) pp:990-992
Publication Date(Web):30 April 2010
DOI:10.1016/j.matlet.2010.01.083
Silica nanoboxes have been successfully synthesized via a simple hard-template method at room temperature. The MnCO3 nanocubes are firstly employed as the hard template. Scanning electron microscopy (SEM) is used to characterize silica nanoboxes and indicates the hollow structure of products. The shell thickness of nanoboxes can be well controlled by the amount of tetraethylorthosilicate (TEOS) and the surface area is calculated through the N2 adsorption–desorption isotherm. Based on these results, a plausible mechanism is proposed to explain the formation of silica nanoboxes. In addition, preliminary tests demonstrate that the silica nanoboxes are capable of being loaded and releasing Rhodamine B, thus showing a great potential in the controlled delivery applications.
Co-reporter:Xinping Li, Yanan Gao, Li Yu, Liqiang Zheng
Journal of Solid State Chemistry 2010 Volume 183(Issue 6) pp:1423-1432
Publication Date(Web):June 2010
DOI:10.1016/j.jssc.2010.04.001
Polycrystalline CdS hollow nanospheres with diameter of about 130 nm have been successfully synthesized in high yield by an ionic liquid (IL) assisted template-free hydrothermal method for the first time. Both the molar ratios of Cd/S precursor in the solution and the reaction temperature play important roles in the formation of the CdS hollow nanospheres. The concentrations of capping agent hexamethylenetetramine (HMT) and polyvinylpyrrolidone (PVP) are also crucial for the morphology and size of the final product. IL was found to be a key component in the formation of CdS hollow structures, because solid spheres were obtained in the absence of IL. A subsequent growth mechanism of hollow interior by localized Ostwald ripening process has been further discussed. Such hollow structures show high photocatalytic ability in the photodegradation of methylene blue.TEM images of typical as-prepared CdS hollow nanospheres.
Co-reporter:Wenpei Kang;Bin Dong;Yanan Gao
Colloid and Polymer Science 2010 Volume 288( Issue 12-13) pp:1225-1232
Publication Date(Web):2010 August
DOI:10.1007/s00396-010-2254-2
The aggregation behavior of long-chain imidazolium ionic liquids, 1-alkyl-3-methyl-imidazolium bromide (CnmimBr, n = 12, 14, 16) was studied by surface tension measurements in a room temperature ionic liquid, ethylammonium nitrate (EAN), at various temperatures. A series of parameters including critical micelle concentration (cmc), surface tension at the cmc (γcmc), and the effectiveness of surface tension reduction (Πcmc) were obtained. In addition, from the cmc values and their temperature dependence, we estimated the thermodynamic parameters of the micelle formation, \( \Delta G_{\rm{m}}^0 \), \( \Delta H_{\rm{m}}^0 \), and \( \Delta S_{\rm{m}}^0 \). The contribution of enthalpy term to the micelle formation is superior to that of entropy term. 1H NMR was performed to study the CnmimBr micelle formation mechanism in EAN.
Co-reporter:Na Li, Shaohua Zhang, Hongchao Ma and Liqiang Zheng
Langmuir 2010 Volume 26(Issue 12) pp:9315-9320
Publication Date(Web):March 19, 2010
DOI:10.1021/la100215z
We demonstrate here the aggregation behavior of a nonionic surfactant Triton X-100 in two 1-butyl-3-methylimidazolium ionic liquids (the hydrophilic IL [bmim][BF4] and the hydrophobic IL [bmim][PF6]) by surface tension measurements. The effects of added water on the microstructure of Triton X-100 in ILs micelles are investigated. When small amounts of water are added to Triton X-100 in [bmim][PF6] micelles, the water molecules are first bound to the ethylene oxide (EO) units of Triton X-100 and then form the water pool in the core of the microemulsion. When water molecules are added to the Triton X-100 in [bmim][BF4] micelles, there is no microemulsion formed; these water molecules are first solubilized in [bmim][BF4]. When the solubilization is saturated, the water molecules start to bind to the EO group of Triton X-100; these results are confirmed by UV−vis, FTIR, and 1H NMR spectra.
Co-reporter:Bin Dong, Yan’an Gao, Yijin Su, Liqiang Zheng, Jingkun Xu and Tohru Inoue
The Journal of Physical Chemistry B 2010 Volume 114(Issue 1) pp:340-348
Publication Date(Web):October 21, 2009
DOI:10.1021/jp908136f
Three amphiphilic imidazolium ionic liquids (ILs), 1-[n-(N-carbazole)alkyl]-3-methylimidazolium bromide [carbazoleCnmim]Br (n = 6, 10, and 12), that incorporate a fluorescent carbazole moiety at the terminal of the hydrocarbon chain, were designed and synthesized. Their surface activity, aggregation behavior, and thermodynamics of micelle formation in aqueous solutions were systematically investigated by surface tension, electrical conductivity, and 1H NMR spectroscopy. The incorporation of bulky carbazole groups led to the loose arrangement of [carbazoleCnmim]Br molecules at the air−water interface. Both the enhanced hydrophobicity and the π−π interaction due to the incorporation of carbazole groups contributed to the lower critical micelle concentration (cmc) and higher micellar aggregation number, reflecting a strong capability of the designed carbazole-tailed imidazolium ILs for the formation of micelle. The analysis of 1H NMR spectra revealed that the carbazole moieties may overlap with the middle methylenes of the alkyl chains. The amphiphilic carbazole-tailed imidazolium ILs demonstrated strong and stable fluorescence properties, indicating their potential application in the combined field of surface chemistry and photochemistry.
Co-reporter:Shaohua Zhang, Yanan Gao, Bin Dong, Liqiang Zheng
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2010 Volume 372(1–3) pp:182-189
Publication Date(Web):3 December 2010
DOI:10.1016/j.colsurfa.2010.10.011
The effect of added long-chain ionic liquid 1-dodecyl-3-methylimidazolium tetrafluoroborate ([C12mim][BF4]) on Triton X-100 aqueous solution has been studied by surface tension measurements, electrical conductivity, 1H NMR and FF-TEM technologies. The surface tension measurements revealed that the ionic liquid [C12mim][BF4] can increase the critical micelle concentration (CMC) of Triton X-100 dramatically, suggesting that it is not conducive to the micelle formation of Triton X-100. The electrical conductivity results showed very interesting features. The electrical conductivity curves of Triton X-100 are very different while the concentration of added [C12mim][BF4] is below and upon its CMC. The 1H NMR data demonstrated that there are hydrogen-bond interactions between the imidazolium cation of [C12mim][BF4] and the hydrophilic PEO groups of Triton X-100 and hydrophobic interactions between the dodecyl chain of the imidazolium cation and the hydrophobic chain with phenyl of Triton X-100. Through these two kinds of interactions, [C12mim][BF4] and Triton X-100 can form mixed micelles.Graphical abstractHydrogen-bond interactions between the imidazolium cation of [C12mim][BF4] and the hydrophilic PEO groups of Triton X-100 and hydrophobic interactions between the dodecyl chain of the imidazolium cation and the hydrophobic chain of Triton X-100 occur when Triton X-100 is added into [C12mim][BF4] aqueous solutions. Through these two kinds of interactions, [C12mim][BF4] and Triton X-100 can form mixed micelles.Research highlights▶ The physicochemical properties of Triton X-100 aqueous solutions can be modified by addition of long-chain ionic liquid [C12mim][BF4]. ▶ The effect of added ionic liquid [C12mim][BF4] on the micelle formation of Triton X-100 results from hydrogen-bond interactions and hydrophobic interactions between them. ▶ The change of the morphology of the aggregates formed by [C12mim][BF4]/Triton X-100 is demonstrated by FF-TEM.
Co-reporter:Mingwei Zhao, Yanan Gao, Liqiang Zheng
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2010 Volume 369(1–3) pp:95-100
Publication Date(Web):20 October 2010
DOI:10.1016/j.colsurfa.2010.08.015
The phase behavior of a surfactant-like ionic liquid 1-tetradecyl-3-methylimidazolium chloride (C14mimCl) in a room-temperature ionic liquid ethylammonium nitrate (EAN) is studied. The lyotropic liquid crystalline (LLC) phases formed in the binary mixture are thoroughly investigated by polarized optical microscopy (POM) and small-angle X-ray scattering (SAXS) measurements, and the temperature effect on the LC phases is also elucidated. Then, a hexagonal (H1) LC phase was used to disperse multi-walled carbon nanotubes (MWCNTs). Both POM images and SAXS patterns indicate that, the dispersion of MWCNTs cannot break the structure of H1 phase. By comparing the rheological properties before and after dispersing, it could be found that the incorporation of MWCNTs has increased the viscosity of H1 phase.
Co-reporter:Jie Liu, Liqiang Zheng, Dezhi Sun, Xilian Wei
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2010 Volume 358(1–3) pp:93-100
Publication Date(Web):5 April 2010
DOI:10.1016/j.colsurfa.2010.01.034
Complex formation between sodium carboxymethylcellulose (NaCMC) and 1-dodecyl-3-methylimidazolium bromide (C12mimBr) has been studied by isothermal titration microcalorimetry (ITC), turbidimetric titration, and the surface tension measurements at varied concentrations of NaBr. The addition of salt is found to influence the formation of C12mimBr/NaCMC complexes markedly. At CNaBr < 0.20 M, C12mimBr forms micelle-like aggregates with the NaCMC polymer chains to form C12mimBr/NaCMC complexes above the critical aggregate surfactant concentration (C1). Free C12mimBr micelles are formed at Cm before the saturation concentration of surfactant on the NaCMC chains (C2). However, when CNaBr > 0.20 M, there is no polyelectrolyte/surfactant complex formation because of complete salt screening of the electrostatic attraction between C12mimBr micelles and the NaCMC chains. Additionally, the addition of salt to a system of 0.01 g/L NaCMC and fixed C12mimBr concentration induces the formation of C12mimBr/NaCMC complexes when CNaBr < 0.20 M, and dissociates the complexes at CNaBr > 0.20 M. The salt effect on complex formation is explained as the result of a competition between the screening interaction (the addition of NaBr screens the electrostatic attraction between surfactant headgroups and stabilizes surfactant micelles) and the increasing interaction (the addition of NaBr compresses the diffusive electric double layers and hence reduces the repulsion between the surfactant heads and carboxylate groups).
Co-reporter:Xiangtao Bai, Xinwei Li and Liqiang Zheng
Langmuir 2010 Volume 26(Issue 14) pp:12209-12214
Publication Date(Web):May 25, 2010
DOI:10.1021/la101602a
Chiral ionic liquid monolayer-stabilized gold nanoparticles were synthesized in a two-phase liquid−liquid system and found to self-assemble into ringlike structures at the air/water interface. Control experiments with long-chain ILs revealed that the molecular structure of the CIL significantly affects the formation of the gold nanoparticle ring structures. A possible mechanism based on Marangoni−Bénard convection in evaporating droplets was proposed. These gold nanoparticle structures were shown to yield a large SERS enhancement for Rhodamine 6G.
Co-reporter:Xiangtao Bai, Hongchao Ma, Xinwei Li, Bin Dong, and Liqiang Zheng
Langmuir 2010 Volume 26(Issue 18) pp:14970-14974
Publication Date(Web):August 24, 2010
DOI:10.1021/la102674f
Gold nanoparticles stabilized with different capping agents were synthesized in a two-phase liquid−liquid system and found to self-assemble into various patterns at the air/water interface. The shapes of the patterns are closely related to the molecule structures of the capping agents. Systems with mixed capping agents were also investigated, and honeycomb patterns can be obtained in this way. T-shape and H-shape patterns were also observed. A possible mechanism based on Marangoni−Benard convection in evaporating droplets is proposed.
Co-reporter:Jie Yuan, Xiangtao Bai, Mingwei Zhao and Liqiang Zheng
Langmuir 2010 Volume 26(Issue 14) pp:11726-11731
Publication Date(Web):June 8, 2010
DOI:10.1021/la101221z
The phase behavior of an aqueous catanionic surfactant system, composed of a long-chain imidazolium ionic liquid 1-dodecyl-3-methylimidazolium bromide (C12mimBr) and sodium dodecyl sulfate (SDS), is described. The phase diagram of the catanionic system was determined by electrical conductivity measurements and the formation of vesicles in a birefringent Lα phase characterized by transmission electron microscopy (TEM) and freeze-fracture transmission electron microscopy (FF-TEM). Rheological measurements were used to characterize the macroscopic properties of the birefringent Lα phase. Both electrostatic and hydrophobic interactions contribute to the vesicle formation in the catanionic system. Compared to the DTAB/SDS aqueous solution, differences between the imidazolium and trimethylammonium headgroups geometric packing and charge density induce the different phase behavior in each system. Silica hollow spheres, with diameters 30−60 nm and a wall thickness of 8−10 nm, were prepared by using the vesicles as the templates. The hollow silica spheres were characterized by TEM, scanning electron microscopy (SEM), and nitrogen adsorption−desorption. The results suggest additional application for ionic liquid based vesicles to be used as templates for the synthesis of hollow inorganic materials.
Co-reporter:Mingwei Zhao, Yanan Gao and Liqiang Zheng
The Journal of Physical Chemistry B 2010 Volume 114(Issue 35) pp:11382-11389
Publication Date(Web):August 17, 2010
DOI:10.1021/jp103728x
The phase behavior of a surfactant-like ionic liquid, N-hexadecyl-N-methylpyrrolidinium bromide (C16MPB), was studied in both water and a room temperature ionic liquid, ethylammonium nitrate (EAN). Polarized optical microscopy (POM) and small-angle X-ray scattering (SAXS) measurements were employed to investigate the phase behavior of the two systems and to determine which lyotropic liquid crystalline (LC) phases were formed. With increasing C16MPB concentration, an isotropic solution phase, a hexagonal (H1) phase, and a cubic phase (V2) are all present in either EAN or H2O. The structural parameters of the H1 phase were calculated from SAXS patterns, which show the structural changes as a function of the amount of C16MPB. The rheological results reveal that the H1 phase constructed by C16MPB in EAN displays a typical Maxwell behavior, whereas the H1 phase formed by C16MPB in water shows a gel-like behavior, unlike traditional cationic surfactants. POM and differential scanning calorimetry (DSC) results demonstrate that the lyotropic LC phase in EAN has a higher thermal stability than that formed in H2O, which may be important to extend the applications of the LC phase.
Co-reporter:Bin Dong, Daifeng Song, Liqiang Zheng, Jingkun Xu, Na Li
Journal of Electroanalytical Chemistry 2009 Volume 633(Issue 1) pp:63-70
Publication Date(Web):1 August 2009
DOI:10.1016/j.jelechem.2009.04.032
An air and moisture stable ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6) was utilized as an electrolyte for the direct anodic oxidation electropolymerization of fluorene. The corresponding electroactive polyfluorene films showed good redox activity and structural stability. 1H NMR and FTIR spectra together with density functional theory calculations indicated that the polymerization of fluorene occurred at the C2 and C7 positions. Scanning electron microscopy results demonstrated that smooth and compact polyfluorene films were obtained, due to the use of bmimPF6 as both the growth medium and the electrolyte. Doped polyfluorene films were examined to oxidize formic acid in 0.5 mol/L sulfuric acid by cyclic voltammetry and demonstrated stable electrocatalytic activity, showing their potential use in fuel oxidation.
Co-reporter:Bin Dong, Jingkun Xu, Liqiang Zheng, Jian Hou
Journal of Electroanalytical Chemistry 2009 Volume 628(1–2) pp:60-66
Publication Date(Web):1 April 2009
DOI:10.1016/j.jelechem.2009.01.011
The electrosyntheses of poly(3-methoxythiophene) (PMOT) by direct anodic oxidation of MOT in novel ionic liquid microemulsions, BmimPF6/Tween 20/H2O, have been investigated. Among water-in-BmimPF6 (W/IL), bicontinuous (BC), and BmimPF6-in-water (IL/W) sub-regions, IL/W was found to be the most suitable medium for the electropolymerization of MOT. The use of IL/W microemulsions remarkably reduces the amount of IL, which is really expensive as electrolyte. BmimPF6 serves both as the core of IL/W microemulsions and as the supporting electrolyte and thus presents a novel microenvironment for the electropolymerization of MOT. Thus, MOT microdroplets were assembled on a bare ITO electrode and polymerized into PMOT microcups. In addition, the oxidation onset potential of MOT in IL/W microemulsions was lower than that in micellar aqueous solutions or conventional organic solvents. As-formed PMOT films obtained in IL/W microemulsions had an electrical conductivity of 3.8 S/cm and could be dissolved in many conventional organic solvents, including dichloromethane, chloroform, acetonitrile, and dimethyl sulfoxide with green-light emitting property.
Co-reporter:Guo-Li Li, Li-Qiang Zheng, Jin-Xin Xiao
Journal of Fluorine Chemistry 2009 Volume 130(Issue 7) pp:674-681
Publication Date(Web):July 2009
DOI:10.1016/j.jfluchem.2009.05.006
A variety of fluorinated surfactants soluble in organic solvent were prepared, including C8F17SO2NHCnH2n+1 (n = 2, 4, 6, 8, 10), C8F17SO2NHR (R = C6H11, C6H5), C8F17SO2N(CnH2n+1)2 (n = 1, 2, 3, 4) and C8F17SO2NH(CH2)nNHO2SC8F17 (n = 6, 10). Their surface activities in various organic solvents were determined by surface tension measurement. The results showed that these fluorinated surfactants can reduce the surface tension of both polar and non-polar organic solvents. In general, organic solvents with strong polarity or long alkyl chain are beneficial to increase the surface activity of these polar fluorinated surfactants. By comparing fluorinated surfactants with the same fluorocarbon segment and connecting group, C8F17SO2N(CnH2n+1)2 (n = 1, 2, 3, 4) showed lower surface activity in organic solvents than C8F17SO2NHCnH2n+1 (n = 2, 4, 6, 8) with an equal carbon number of the solvophilic group. Through surface tension vs. concentration curves given for N-octyl perfluorooctanesulfonamide in various organic solvents, a break point like the critical micelle concentration of ordinary surfactants in aqueous solutions was observed, and the effect of the different types of organic solvents on adsorption and aggregation behavior was also studied.
Co-reporter:Xiangtao Bai, Liqiang Zheng, Hongguo Liu, Mingwei Zhao
Materials Letters 2009 Volume 63(13–14) pp:1156-1158
Publication Date(Web):31 May 2009
DOI:10.1016/j.matlet.2009.02.026
Tadpole-shaped nanoplates, linearly arranged nanoparticles and triangular and hexagonal nanoplates were synthesized under a Langmuir monolayer of a cationic fluorocarbon surfactant, FC-4 (C3F7O(CF(CF3)CF2O)2CF(CF3)CONH(CH2)3N+(C2H5)2CH3I−) through interfacial reduction of AuCl4− by formaldehyde gas. Reports about such tadpole-shaped nanoparticles are relatively scarce. The predominantly plate-like particles are mainly nearly perfect triangular and hexagonal nanocrystals, of micrometer scale in diameter. The Au nanoparticles are characterized using transmission electron microscopy (TEM) and selected-area electron diffraction (SAED). The atomically flat planar surfaces of the Au nanoplates correspond to {111} planes and the lateral surfaces are {110} planes. The surface pressure strongly influences the formation of different Au nanostructures. A potential mechanism of such diverse morphologies is also discussed.
Co-reporter:Na Li, Shaohua Zhang, Liqiang Zheng and Tohru Inoue
Langmuir 2009 Volume 25(Issue 18) pp:10473-10482
Publication Date(Web):May 14, 2009
DOI:10.1021/la901170j
The cationic fluorinated surfactant, FC-4, unlike other surfactants, forms micelles in the room temperature ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (bmimTf2N). Surface tension, freeze-fracture transmission electron microscopy, 19F NMR, 1H NMR, and Fourier transform infrared measurements revealed that (i) the FC-4 cation forms an ion pair with the Tf2N anion, (ii) the ion pairs undergo association to form premicellar aggregates, and (iii) the premicellar aggregates transform into micelles at the critical micelle concentration (CMC). The thermodynamic parameters for micelle formation derived from the temperature dependence of the CMC demonstrated that the solvophobic interaction between the solvophobic tails of the surfactant molecules is rather weak in bmimTf2N compared with other ionic liquids, in accordance with the observation that surfactants do not readily form micelles in bmimTf2N. The fact that FC-4 forms micelles in such an inconvenient solvent is attributed to the ion-pair formation between the surfactant cation and the ionic liquid anion.
Co-reporter:Yanan Gao, Na Li, Xinwei Li, Shaohua Zhang, Liqiang Zheng, Xiangtao Bai and Li Yu
The Journal of Physical Chemistry B 2009 Volume 113(Issue 1) pp:123-130
Publication Date(Web):December 15, 2008
DOI:10.1021/jp809166f
Nonionic surfactant Triton X-100 was shown to aggregate and form micellar aggregation in ionic liquids (ILs), 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4) and 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6). The surface tension measurements revealed that the dissolution of Triton X-100 in ILs depressed the surface tension in a manner analogous to aqueous solutions, and a relatively higher critical micellar concentration (CMC) was obtained compared to that of water. Freeze-fracture transmission electron microscopy (FFTEM) shows that the micelles have an irregular droplet shape, which is larger than that formed in water. The micellar droplets preferred to assemble into larger clusters. 1H NMR and two-dimensional rotating frame nuclear Overhauser effect (NOE) experiments (2D ROESY) show that the addition of Triton X-100 destroyed the ion pairs of pure ILs due to the electrostatic interaction between the positively charged imidazolium cation of ILs and the electronegative oxygen atoms of oxyethylene (OE) units of Triton X-100. The electrostatic interaction behaves similar to hydrogen bond that occurred between the OE units of nonionic surfactants and water molecules in aqueous micelles and cooperates with solvatophobicity, leading to the formation of IL micelles. The 2D ROESY analysis reveals that the microstructures of Triton X-100-based micelles in ILs are not regular spherical, which accords with the FFTEM image. Similar to the aqueous micellar systems, the hydrophobic interaction or solvatophobicity was found to drive the formation of micelles.
Co-reporter:Xin-Wei Li, Jin Zhang, Li-Qiang Zheng, Bin Chen, Li-Zhu Wu, Feng-Feng Lv, Bin Dong and Chen-Ho Tung
Langmuir 2009 Volume 25(Issue 10) pp:5484-5490
Publication Date(Web):April 15, 2009
DOI:10.1021/la803336g
The phase behavior of the ternary system consisting of an ionic liquid (1-tetradecyl-3-methylimidazolium bromide [C14mim]Br), p-xylene, and water were investigated. Depending on the composition of the ternary system, formation of hexagonal and lamellar liquid crystals as well as microemulsions was observed. 1H NMR spectroscopy study, 2D ROESY spectroscopic analysis, and rheological measurements of the microemulsions indicated that p-xylene is preferably located in the hydrophobic core and the palisade shells of the microemulsions. The sizes of the microemulsion droplets for the samples with water/[C14mim]Br ratio of 78:22 are measured by both dynamic light scattering (DLS) and transmission electron microscopy with the freeze−fracture technique (FF-TEM). Upon change of the mole ratio of the solubilized xylene to [C14mim]Br from 0 to 2.4, the diameters of the microemulsion droplets increase from ca. 20 to 90 nm and size distribution gets broad. These microemulsions can solubilize and preorientate anthracene derivatives with a polar 9-substituent, and thus may enhance the head-to-head cyclomers in the photocyclization of these substrates.
Co-reporter:Yanan Gao, Na Li, Liane Hilfert, Shaohua Zhang, Liqiang Zheng and Li Yu
Langmuir 2009 Volume 25(Issue 3) pp:1360-1365
Publication Date(Web):January 8, 2009
DOI:10.1021/la803452m
In the present contribution, results concerning the effect of temperature on the nonionic surfactant Triton X-100 based 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4)-in-cyclohexane and bmimBF4-in-toluene ionic liquid (IL) reverse microemulsions are reported. Dynamic light scattering (DLS) along with freeze-fracture transmission electron microscopy (FF-TEM) measurements revealed that the sizes of single microemulsion droplets increased with increasing temperature. However, a decreased temperature led to the appearance of droplet clusters, which have also been observed previously when the single microemulsion droplets were swollen by added bmimBF4 to a certain extent (Gao, Y. A.; Vogit, A.; Hilfert, L.; Sundmacher, K. ChemPhysChem, 2008, 9, 1603−1609). Compared to traditional aqueous microemulsions, IL microemulsions revealed relatively high temperature-independence. The droplet-shaped microstructure was always kept in a large range of temperature. The temperature-independence is ascribed to the temperature-insensitive electrostatic attraction between the solubilized bmimBF4 and Triton X-100, which was considered to be the driving force for solubilizing bmimBF4 into the cores of Triton X-100 aggregates. Two-dimensional rotating frame nuclear Overhauser effect (NOE) experiments (ROESY) further confirmed the microstructural change with temperature.
Co-reporter:Xin-Wei Li, Jin Zhang, Bin Dong, Li-Qiang Zheng, Chen-Ho Tung
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2009 Volume 335(1–3) pp:80-87
Publication Date(Web):5 March 2009
DOI:10.1016/j.colsurfa.2008.10.031
1-Alkyl-3-methylimidazolium bromide (CnmimBr), are substituted for surfactants and formed lyotropic liquid crystalline phases with p-xylene and water. Small angle X-ray scattering (SAXS), polarized optical microscopy (POM), 2H nuclear magnetic response (2H NMR) and rheological measurement were performed to investigate the lyotropic liquid crystalline phases. A lyotropic bicontinuous cubic phase formed in imidazolium-type ionic liquid (IL) system was found for the first time. Moreover, the effect of chain length of CnmimBr on the phase behavior, structural parameters and rheological properties was studied. The strong “π–π stacking” of imidazolium based ILs and their “π-cation” interactions with p-xylene molecules have unique effect on the structural parameters, especially the thickness of the water channel (dW).
Co-reporter:Mingwei Zhao, Liqiang Zheng, Xiangtao Bai, Na Li, Li Yu
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2009 Volume 346(1–3) pp:229-236
Publication Date(Web):20 August 2009
DOI:10.1016/j.colsurfa.2009.06.021
Silica products with two different morphologies were synthesized using nonaqueous ionic liquid microemulsion droplets as templates. The morphologies of the obtained products were characterized by both transmission electron microscopy (TEM) and scanning electron microscopy (SEM). By adjusting the reaction conditions, ellipsoidal nanoparticles were formed under acidic conditions, while hollow silica spheres were obtained under alkaline conditions. It is demonstrated that the size distribution of hollow silica spheres was narrower than that of the ellipsoidal nanoparticles. The various vibration modes of different functional groups in the silica materials were revealed by Fourier transform infrared (FTIR) spectroscopy. The two samples were both shown to be amorphous, not crystalline by X-ray diffraction (XRD). A simple diagram of the formation process including the hydrolysis and condensation reactions is given. Furthermore, a probable mechanism for the formation of silica materials under acidic or alkaline conditions is presented, which may be helpful for better understanding the different silica materials obtained under different conditions.
Co-reporter:Jiapei Wu, Jin Zhang, Liqiang Zheng, Xueyan Zhao, Na Li, Bin Dong
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2009 Volume 336(1–3) pp:18-22
Publication Date(Web):20 March 2009
DOI:10.1016/j.colsurfa.2008.11.011
The phase diagram of ternary mixtures of 1-dodecyl-3-methylimidazolium bromide (C12mimBr)/1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4)/H2O is constructed at 25 °C. The formed hexagonal liquid crystalline phase in the mixtures is investigated by the polarized optical microscopy (POM), small-angle X-ray scattering (SAXS), and rheology measurements in comparison with the hexagonal phase formed in the ternary system, dodecyltrimethylammonium bromide (DTAB)/bmimBF4/H2O. The structural parameters of the lyotropic liquid crystalline phases are calculated. The increase of the lattice parameter with the increase of the bmimBF4 content is attributed to the location region of bmimBF4 in the water layer of the hexagonal phase. Furthermore, the denser aggregation of the cylindrical units in the hexagonal liquid crystalline phase formed in the C12mimBr system than in the DTAB system could be concluded from the SAXS and rheological measurements.The lyotropic liquid crystalline phases formed in the ternary mixtures of 1-dodecyl-3-methylimidazolium bromide (C12mimBr)/1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4)/H2O is studied by small-angle X-ray scattering, polarized optical microscopy and rheology measurements.
Co-reporter:Yanan Gao, Na Li, Shaohua Zhang, Liqiang Zheng, Xinwei Li, Bin Dong and Li Yu
The Journal of Physical Chemistry B 2009 Volume 113(Issue 5) pp:1389-1395
Publication Date(Web):January 12, 2009
DOI:10.1021/jp808522b
The role of four organic solvents in the formation process of 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4) based ionic liquid (IL) microemulsions is investigated. The results showed that the addition of Triton X-100 remarkably decreased the conductivity of bmimBF4. The added organic solvents provided a strong apolar environment for the hydrophobic tails of Triton X-100 and caused the surfactant molecules to aggregate into the interfacial film of oil-in-bmimBF4 (O/IL) microemulsions. As a result, the conductivities of the solutions were initially increased because the insulative Triton X-100 molecules were assembled, which corresponded to increasing the concentration of continuous bmimBF4 solutions. The hydrophobic interaction between the dispersed organic solvents and the hydrophobic tails of Triton X-100 may be the driving force for the formation of O/IL microemulsions. The droplets of O/IL microemulsions were successively swollen by organic solvents, and a bicontinuous IL-containing microemulsion was observed by freeze-fracture transmission electron microscopy for the first time. The current study can help in further understanding the ILs-containing microemulsions and thereby improve microemulsion theory.
Co-reporter:Xiangtao Bai, Yanan Gao, Hong-guo Liu and Liqiang Zheng
The Journal of Physical Chemistry C 2009 Volume 113(Issue 41) pp:17730-17736
Publication Date(Web):September 2, 2009
DOI:10.1021/jp906378d
Uniform gold nanorods were prepared via a three-step seed-mediated growth method using a long-chain ionic liquid (IL), 1-dodecyl-3-methylimidazolium bromide (C12mimBr), as a capping agent. Both AgNO3 and HNO3 were used in the synthesis process. The aspect ratio, R, of the nanorods was increased when AgNO3 was replaced by HNO3. HRTEM revealed that these well-crystallized nanorods are all enclosed by five {100} facets and their cross section is pentagon. The interaction energies between the individual surfactants and different gold crystalline planes were calculated using a molecular dynamics simulation. The results showed that the interaction energies between the C12mimBr and different gold crystalline planes were smaller than those of CTAB based system. The catalytic experiments showed that the short gold nanorods had excellent catalytic efficiency for the reduction of nitro compounds.
Co-reporter:Na Li;Shaohua Zhang;Xinwei Li;Li Yu
Colloid and Polymer Science 2009 Volume 287( Issue 1) pp:103-108
Publication Date(Web):2009 January
DOI:10.1007/s00396-008-1946-3
The effect of a common polymer, polyethylene glycol with molecular weight of 400 (PEG-400) on the microstructure of 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4)/Triton X-100/cyclohexane ionic liquid (IL) reverse microemulsion has been investigated. The addition of PEG-400 leaded to the linear increase of the microemulsion droplet size, in accordance with the observation of dispersed phase, showing that PEG-400 was only solubilized into the polar interior of the IL microemulsions. FTIR spectroscopic analysis indicated that the addition of PEG-400 decreased the electrostatic interaction between the oxygen atoms of OE units and the positive electrical charged imidazolium cation of bmimBF4. At the same time, the oxygen atoms of PEG-400 can also interact with the imidazolium cation. These results suggested that small amounts of PEG-400 entered the palisade layers of the IL microemulsion. The conductivity of the IL reverse microemulsions was decreased owing to the dilution of conducting polar cores by the addition of insulative PEG-400, indicating that PEG-400 was only solubilized into the reverse IL microemulsion interior. The conclusion was further supported by viscosity measurement.
Co-reporter:Bin Dong, Yaohui Xing, Jingkun Xu, Liqiang Zheng, Jian Hou, Feng Zhao
Electrochimica Acta 2008 Volume 53(Issue 19) pp:5745-5751
Publication Date(Web):1 August 2008
DOI:10.1016/j.electacta.2008.03.049
The electrochemical polymerization of selenophene in a room temperature ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF6) led to the formation of free-standing and highly conducting polyselenophene (PSe) films with an electrical conductivity as high as 2.3 S/cm, higher than PSe electrodeposited in conventional media. The polymerization rate was significantly improved as BmimPF6 served as both the growth medium and an electrolyte. PSe showed good electroactivity and stability even in concentrated sulfuric acid. Infrared (IR) spectra confirmed the polymerization mainly through α–α′ coupling. Scanning electron microscopy results indicated the formation of smooth and compact PSe films.
Co-reporter:Bin Dong, Jin Zhang, Liqiang Zheng, Suqing Wang, Xinwei Li, Tohru Inoue
Journal of Colloid and Interface Science 2008 Volume 319(Issue 1) pp:338-343
Publication Date(Web):1 March 2008
DOI:10.1016/j.jcis.2007.11.040
The growth and structure of the aqueous micellar solutions of a surface active ionic liquid, 1-hexadecyl-3-methylimidazolium bromide (C16mimBr), in the presence of an organic salt sodium tosylate (NaTos), were investigated by rheological measurements and freeze-fracture transmission electron microscopy at room temperature (298 K). As in some conventional ionic surfactant/salt aqueous systems, wormlike micelles and network structures could be formed in the C16mimBr/NaTos aqueous solutions, according to measurements of the zero-shear viscosity, the entanglement length, the average contour length, as well as application of the Cox–Merz empirical rule and Cole–Cole plots. FF-TEM images further confirmed that wormlike micelles were formed in these aqueous solutions. The wormlike micelles presented here would expand potential applications of ionic liquids in home care products, oilfield stimulation fluids, and nanobiotechnology.Salt-induced viscoelastic wormlike micelles formed in surface active ionic liquid aqueous solutions were investigated.
Co-reporter:Jin Zhang, Bin Dong, Liqiang Zheng, Na Li, Xinwei Li
Journal of Colloid and Interface Science 2008 Volume 321(Issue 1) pp:159-165
Publication Date(Web):1 May 2008
DOI:10.1016/j.jcis.2008.01.020
The phase behavior of ternary mixtures of 1-cetyl-3-methylimidazolium bromide (C16mim-Br)/p-xylene/water is studied by small-angle X-ray scattering (SAXS), polarized optical microscopy (POM), and rheology measurements. Two types of lyotropic liquid crystalline phases are formed in the mixtures: hexagonal and lamellar. The structural parameters of the lyotropic liquid crystalline phases are calculated. Greater surfactant content in the sample leads to denser aggregation of the cylindrical units in the hexagonal liquid crystalline phase. The increase in lattice parameter and thickness of the water layer in lamellar phase are attributed to the increase of water content, and the area per surfactant molecule at the hydrophobic/hydrophilic interface for lamellar phase is found to be larger than that for hexagonal phase. The structural parameters of the liquid crystalline phases formed from the cetyltrimethylammonium bromide (CTAB) system are larger than those for the C16mim-Br system. The rheological properties of the samples are also found to be related to the structure of the liquid crystalline phases.The phase behavior of the ternary mixtures of 1-cetyl-3-methylimidazolium bromide/p-xylene/water is studied by small angle X-ray scattering, polarized optical microscopy and rheology measurements.
Co-reporter:Na Li, Shaohua Zhang, Liqiang Zheng, Bin Dong, Xinwei Li and Li Yu
Physical Chemistry Chemical Physics 2008 vol. 10(Issue 30) pp:4375-4377
Publication Date(Web):19 Jun 2008
DOI:10.1039/B807339B
The aggregation behavior of long-chain ionic liquids 1-alkyl-3-methylimidazolium bromide (CnmimBr) in another ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4), was studied for the first time. Surface tension measurements revealed that aggregates are formed by CnmimBr, and freeze fracture transmission electron microscopy (FF-TEM) observations suggested the aggregates are spheres with a size much larger than traditional micelles. The sizes of the aggregates were further confirmed by dynamic light scattering (DLS) measurements.
Co-reporter:Xiangtao Bai, Liqiang Zheng, Na Li, Bin Dong and Hongguo Liu
Crystal Growth & Design 2008 Volume 8(Issue 10) pp:3840-3846
Publication Date(Web):August 29, 2008
DOI:10.1021/cg800549e
Triangular, hexagonal, and truncated triangular single-crystal gold nanoplates are successfully synthesized under Langmuir monolayers of long-chain ionic liquid molecules 1-hexadecyl-3-methylimidazolium bromide (C16mimBr) through interfacial reduction of AuCl4− by formaldehyde gas. The Au nanoparticles are characterized using transmission electron microscopy (TEM), selected-area electron diffraction (SAED), high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), and UV−vis spectroscopy. It is found that the size of the Au plates varies from several hundred nanometers to several micrometers, up to 20 μm, and the thickness is ca. 35 nanometers. The atomically flat planar surfaces of the Au nanoplates correspond to {111} planes and the lateral surfaces are {110} planes. The concentration of HAuCl4 aqueous solution strongly influences the formation of the Au nanoplates. The formation of the nanoplates should be attributed to the preferential adsorption of 1-hexadecyl-3-methylimidazolium cations onto the {111} planes of Au nuclei and the connection of small, triangular nanoplates.
Co-reporter:Renyun Zhang, Sebastian Gutmann, Jian Zhou, Xueyan Zhao, Hongguang Li, Liqiang Zheng, Xuemei Wang
Applied Surface Science 2008 Volume 255(Issue 2) pp:585-588
Publication Date(Web):15 November 2008
DOI:10.1016/j.apsusc.2008.06.172
Abstract
In this study, the specific DNA binding behavior of a water soluble C60 derivative (C60DF) and redox-controlled hydrophilic-to-hydrophobic transformations of the relative C60DF monolayer on surfaces of glassy carbon electrode (GCE) have been demonstrated by using in situ electrochemical static contact angle analysis. The results illustrate that in situ electrochemical contact angle detection based on C60DF functional film can be utilized to sensitively probe some specific bio-molecular recognition like DNA interaction, which will provide the new strategy to develop the promising multi-signal responsive biosensors for relevant biological process.
Co-reporter:Yong Qiang Ji, Wei Shan Wang, Gan Zuo Li, Li Qiang Zheng
Chinese Chemical Letters 2008 Volume 19(Issue 4) pp:483-487
Publication Date(Web):April 2008
DOI:10.1016/j.cclet.2008.01.010
Aqueous solution of anionic surfactant, sodium oleate (NaOA), was studied by means of steady-state shear rheology and dynamic oscillatory technique. The system of NaOA/Na3PO4 showed high viscosity, strong viscoelasticity and good ability of countering Ca2+, Mg2+. The Maxwell model and Cole–Cole plot were applied to study the dynamic viscoelasticity of wormlike micelles. The microstructures of the wormlike micelles were characterized by FF-TEM.
Co-reporter:Mingwei Zhao, Liqiang Zheng, Na Li, Li Yu
Materials Letters 2008 Volume 62(Issue 30) pp:4591-4593
Publication Date(Web):15 December 2008
DOI:10.1016/j.matlet.2008.08.047
Hollow silica spheres have been successfully synthesized by using the ionic liquid microemulsion droplets as the template. The morphology and microstructures of the silica spheres were investigated by scanning electron microscopy (SEM), high-resolution transmission electron microscope (HRTEM), and Nitrogen adsorption–desorption measurements. The obtained images showed that the average size of the silica spheres was almost between 150 and 300 nm. The Nitrogen adsorption–desorption investigation on the silica spheres indicated the amorphous structure on the interface. Both of these two results provide us new insights into this novel template and hollow silica spheres were for the first time prepared free of additional acid and alkali conditions. The possible mechanism for the formation of silica spheres has been put forward and discussed in details.
Co-reporter:Quan Cao, Li Yu, Li-Qiang Zheng, Gan-Zuo Li, Yuan-Hua Ding, Jian-Hong Xiao
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2008 Volume 312(Issue 1) pp:32-38
Publication Date(Web):4 January 2008
DOI:10.1016/j.colsurfa.2007.06.024
Aqueous solutions of anionic surfactant, sodium oleate (NaOA), have been studied by means of steady-state shear rheology and dynamic oscillatory technique. The micellar structure can be changed upon the addition of NaCl, Na2CO3 and NaCl/NaOH while NaOA concentration is maintained at 0.060 M. These systems except NaOA/NaCl show high viscosity and strong viscoelasticity. The hydroxide ion is very important for the formation of wormlike micelles. The anions of salts also have effect on the rheological properties of wormlike micelles. Three parameters: intersection frequency ωi, plateau modulus G0 and relaxation time τ are also discussed. The Maxwell model and Cole-Cole plot are applied to investigate the dynamic viscoelasticity of wormlike micelles. Variation in surfactant packing parameter RP can be used to explain the change of rheology and microstructure of the micelles.
Co-reporter:Bin Dong, Xueyan Zhao, Liqiang Zheng, Jin Zhang, Na Li, Tohru Inoue
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2008 Volume 317(1–3) pp:666-672
Publication Date(Web):20 March 2008
DOI:10.1016/j.colsurfa.2007.12.001
Aqueous solutions of long-chain imidazolium ionic liquids have been investigated by surface tension and steady-state fluorescence measurements at room temperature (298 K). The micelle aggregation number (Nagg) was obtained by pyrene fluorescence quenching method. From the surface tension data, critical micelle concentration (cmc), surface tension at the cmc (γcmc), adsorption efficiency (pC20), and effectiveness of surface tension reduction (Πcmc), were determined. Moreover, applying the Gibbs adsorption isotherm, maximum surface excess concentration (Γmax) and minimum surface area per molecule (Amin) at the air–water interface were estimated. The effect of sodium halides, NaCl, NaBr, and NaI, on the surface activity was also investigated. The addition of salts decreases significantly both cmc and γcmc, and the dependence of the salt effect on the anion species is analogous for the case of conventional ionic surfactants. Due to the bulkiness of the imidazolium head group, the microenvironment in long-chain imidazolium ionic liquid micelles exhibits higher polarity compared with the corresponding CnTAB micelles, and the micelle aggregation numbers (Nagg) are smaller than those of CnTAB.
Co-reporter:XinWei Li, XiaoHong Lin, LiQiang Zheng, Li Yu, FengFeng Lv, QiQing Zhang, WeiChang Liu
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2008 Volume 317(1–3) pp:352-359
Publication Date(Web):20 March 2008
DOI:10.1016/j.colsurfa.2007.11.011
In the present contribution, surface-modified SLNs have been prepared from precipitation in an oil-in-water microemulsion, using monocaprate (MC) as solid matrix, polyethylene glycol sorbitan monooleate (Tween80) as emulsifier and poly(ethylene glycol) stearate (PEG-S) as surface modifier. The aim of present work was to evaluate the effect of PEG-S on the phase behavior of MC/Tween80/H2O system as well as on the properties of surface-modified SLNs. Three different PEG-Ss: PEG8-S, PEG40-S and PEG100-S with varying PEG chain length were used to modify SLN. First, the effect of PEG-S on pseudo-ternary phase showed that the presence of PEG-S extended the areas of liquid crystal and microemulsion in the phase diagram. Meanwhile, with increasing the PEG chain length, liquid crystal and microemulsion areas extended to the water corner. In addition, the morphology and microstructure of PEG-S-modified SLN were investigated. The pictures of transmission electron microscope (TEM) and environmental scanning electron microscopy (ESEM) showed that the modified SLNs to be spherical particles, and the average diameters measured by dynamic light scattering (DLS) were between ca. 71 nm and ca. 140 nm. The crystallographic properties of them were characterized by X-ray diffraction (XRD). It was found that PEG-S did not exist in crystallline state in the SLN, both surface-modified and non-modified SLN existed in the amorphous state. Further more, zeta potential analysis and the Fourier transform infrared spectrum (FTIR) were carried out, and the results revealed that conformations of PEG-S on the surface of SLN were different when changing the concentration and the EO chain length of PEG-S both in solid state and liquid state.
Co-reporter:Shaohua Zhang, Na Li, Liqiang Zheng, Xinwei Li, Yanan Gao and Li Yu
The Journal of Physical Chemistry B 2008 Volume 112(Issue 33) pp:10228-10233
Publication Date(Web):July 26, 2008
DOI:10.1021/jp8035132
Three amphiphilic poly(oxyethylene)-poly(oxypropylene)-poly(oxyethylene) ethers triblock copolymers, denoted Pluronic L61 (PEO3PPO30PEO3), Pluronic L64 (PEO13PPO30PEO13), and Pluronic F68 (PEO79PPO30PEO79) were shown to aggregate and form micelles in ionic liquids (ILs) 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4) and 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6). The surface tension measurements revealed that the dissolution of the copolymers in ILs depressed the surface tension in a manner analogous to aqueous solutions. The cmcs of three triblock copolymers increase following the order of L61, L64, F68, suggesting that micellar formation was driven by solvatophobic effect. cmc and γcmc decrease with increasing temperature because hydrogen bonds between ILs and hydrophilic group of copolymers decrease and accordingly enhance the solvatophobic interaction. Micellar droplets of irregular shape with average size of 50nm were observed. The thermodynamic parameters ΔGm0, ΔHm0, ΔSm0of the micellization of block copolymers in bmimBF4 and bmimPF6 were also calculated. It was revealed that the micellization is a process of entropy driving, which was further confirmed by isothermal titration calorimetry (ITC) measurements.
Co-reporter:Na Li, Shaohua Zhang, Liqiang Zheng, Jiapei Wu, Xinwei Li and Li Yu
The Journal of Physical Chemistry B 2008 Volume 112(Issue 39) pp:12453-12460
Publication Date(Web):September 10, 2008
DOI:10.1021/jp8054872
The aggregation behavior of a fluorinated surfactant (FC-4) was studied by surface tension measurements in 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) and hexafluorophosphate ([bmim][PF6]) at various temperatures. A series of surface properties, including adsorption efficiency (pC20), effectiveness of surface tension reduction (ΠCAC), maximum surface excess concentration (Γmax) and minimum surface area/molecule (Amin) at the air−water interface were estimated. By comparing the fluorinated surfactant with traditional surfactants, we deduced that the surface activity of the fluorinated surfactant in ILs was superior to the activity of other surfactants. From the CAC values and their temperature dependence, we estimated the thermodynamic parameters of aggregate formation. The thermodynamic parameters indicate that the aggregate of FC-4 in [bmim][BF4] is a traditional micelle, while the aggregate of FC-4 in [bmim][PF6] is nanodroplets composed of FC-4 molecules segregated from the solution phase. These results were further confirmed by 1H NMR measurements.
Co-reporter:Jiapei Wu, Na Li, Liqiang Zheng, Xinwei Li, Yan’an Gao and Tohru Inoue
Langmuir 2008 Volume 24(Issue 17) pp:9314-9322
Publication Date(Web):July 29, 2008
DOI:10.1021/la801358z
Surface tension measurements were carried out for the solutions of polyoxyethylene (20) sorbitan monolaurate (Tween 20) in 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4) and hexafluorophosphate (bmimPF6) at various temperatures. Two transition points were found in the surface tension−concentration curves at each temperature. The freeze-fracture transmission electron microscopy revealed that two kinds of particles with different sizes are formed at the concentrations of each transition point. Thus, the surfactant concentrations of the two transition points are regarded as critical aggregation concentrations, CAC1 and CAC2. From the CAC values and their temperature dependence, we estimated the thermodynamic parameters of the aggregate formation, ΔGagg0, ΔHagg0, and ΔSagg0. The thermodynamic parameters related to CAC1 are almost independent of temperature. On the other hand, as for the aggregate formation at CAC2, a positiveΔSagg0 contributes to a negative ΔGagg0 at low temperature, while a negative ΔHagg0 contributes to a negative ΔGagg0 at high temperature. The behavior of the thermodynamic parameters as a function of temperature, combined with the variation of 1H NMR chemical shifts of the bmim+ protons as a function of the surfactant concentration, demonstrated that the aggregates formed at CAC1 are nanodroplets of Tween 20 segregated from the solution phase, while those formed at CAC2 are similar to the usual surfactant micelles formed in aqueous solution.
Co-reporter:Jin Zhang;Na Li;Quan Cao;Xiangtao Bai;Yanan Gao Dr. ;Mingwei Zhao;Li Yu;Zhen Li;Bin Dong
ChemPhysChem 2007 Volume 8(Issue 15) pp:2211-2217
Publication Date(Web):20 SEP 2007
DOI:10.1002/cphc.200700382
We demonstrate a novel ionic liquid (IL) microemulsion, consisting of 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4) and nonionic surfactant Triton X-100 prepared in triethylamine which is used either as an organic solvent or a Lewis base. The effects of small amounts of added water on the microstructure of the IL microemulsion are investigated by various techniques. UV/Vis spectroscopic analysis and FTIR spectra indicate that these water molecules are not solubilized into the IL pools of the microemulsions. 1H NMR spectra further show that the added water binds with triethylamine to form a surrounding OH− base environment. Some of OH− ions enter the palisade layers of the IL microemulsions and a continuous base interface is created. The unique solubilization behavior of water reveals that it is possible to use the triethylamine microemulsions as a template to prepare metal hydroxides as well as metal oxides in the microemulsions, which is not possible when using traditional microemulsions.
Co-reporter:Feng-Feng Lv, Shi-Ling Yuan, Li-Qiang Zheng, Na Li, Li-Zhu Wu, Chen-Ho Tung, Tohru Inoue
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2007 Volume 305(1–3) pp:132-137
Publication Date(Web):15 September 2007
DOI:10.1016/j.colsurfa.2007.04.060
The surface behaviors of 3-nonylphenoxy-2-hydroxyl-propyl-trimethyl-ammonium bromide (RTAB), a cationic surfactant, are examined by dynamic surface tensions (DSTs), π–A isotherms and molecular dynamics simulations as a function of pH. While the DST remains almost constant when the pH of the solutions changes from 7.0 to 3.0, which decreases remarkably in alkaline solutions. The results of π–A isotherms indicate that RTAB molecule has a much larger cross-sectional area at the air–water interface in alkaline solutions than that in acidic or neutral solutions. Molecular dynamics (MD) simulation studies revealed that the hydrocarbon chains of the surfactant molecules adsorbed at the air–water interface become conformationally more complex under alkaline solutions than in neutral or acidic conditions. These abnormal surface behaviors of RTAB in alkaline solutions are explained by assuming the binding of a hydroxide ion to the hydroxyl group in RTAB molecule.
Co-reporter:Xue-Yan Zhao, Jing Xu, Li-Qiang Zheng, Xin-Wei Li
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2007 Volume 307(1–3) pp:100-107
Publication Date(Web):15 October 2007
DOI:10.1016/j.colsurfa.2007.05.006
Temperature-sensitive microemulsion-based gels (MBGs) of Pluronic F127 (PEO99–PPO67–PEO99) were formed in microemulsion systems composed of isopropyl myristate (IPM)/Span20/Tween20/H2O, with or without a model drug (chloramphenicol), and the phase behaviors of the systems were investigated. The viscoelastic properties and gelation temperatures of the systems were characterized by rheological measurements. Effects of the concentration of F127 and the model drug (chloramphenicol) on the viscoelastic properties and gelation temperatures were also studied. It was observed that the viscosities of the gels increased and the gelation temperatures decreased with increasing F127 concentration. Chloramphenicol had little effect on the viscosities and gelation temperatures of the MBG. Moreover, chloramphenicol was sustainably released from the MBG system. Freeze-fracture transmission electron microscopy (FF-TEM) demonstrated that the amphiphilic triblock copolymer (F127) self-assembled in the selected microemulsion system and formed network structures. The microstructures of the microemulsion droplets were maintained in the MBG after the addition of F127. The results of fluorescence spectroscopy also supported this conclusion. Based on these results, a plausible schematic model was proposed to explain the mechanism of MBG formation.
Co-reporter:Xiaohong Lin, Xinwei Li, LiQiang Zheng, Li Yu, Qiqing Zhang, Weichang Liu
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2007 Volume 311(1–3) pp:106-111
Publication Date(Web):1 December 2007
DOI:10.1016/j.colsurfa.2007.06.003
Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) are potential drug delivery systems based on solid lipids. Although both carrier types are based on solid lipids, SLN consist of pure solid lipids while NLC are made of a solid matrix entrapping liquid oil. In the present paper, aqueous dispersions of SLN and NLC were successfully prepared by an oil-in-water microemulsion technique using monocaprate (MC) as the solid lipid, medium chain triglyceride (MCT) as the liquid oil and polyethylene glycol sorbitan monooleate (Tween 80) as the emulsifier. The present work aimed to modify the inner structure of an SLN by inducing liquid oil into the system to form an NLC, and then to investigate these new carriers in detail. Several methods including dynamic light scattering (DLS), environmental scanning electron microscopy (ESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectra were applied to characterize the particle size, morphology and structure of the NLC and SLN. DLS data showed that the average diameters of the SLN were ∼42 nm and the diameters of the NLC ranged from ∼25 to ∼120 nm. All samples had polydispersity indexes about 0.27. Using ESEM and TEM, SLN and NLC were observed to be nearly spherical particles. XRD, DSC and FTIR measurements revealed that imperfect crystallization occurred in the inner core of the NLC particles. The results suggest that nanostructured lipid carriers can be produced by this microemulsion method, and incorporation of the liquid oil into the SLN may affect their encapsulation capacity.
Co-reporter:Yan'an Gao Dr.;Na Li ;Xueyan Zhao;Jin Zhang Dr.;Quan Cao;Mingwei Zhao;Zhen Li;Gaoyong Zhang
Chemistry - A European Journal 2007 Volume 13(Issue 9) pp:
Publication Date(Web):19 DEC 2006
DOI:10.1002/chem.200600939
The ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) forms nonaqueous microemulsions with benzene with the aid of nonionic surfactant TX-100. The phase diagram of the ternary system was prepared, and the microstructures of the microemulsion were recognized. On the basis of the phase diagram, a series of ionic liquid-in-oil (IL/O) microemulsions were chosen and characterized by dynamic light scattering (DLS), which shows a similar swelling behavior to typical water-in-oil (W/O) microemulsions. The existence of IL pools in the IL/O microemulsion was confirmed by UV/Vis spectroscopic analysis with CoCl2 and methylene blue (MB) as the absorption probes. A constant polarity of the IL pool is observed, even if small amounts of water are added to the microemulsion, thus suggesting that the water molecules are solubilized in the polar outer shell of the microemulsion, as confirmed by FTIR spectra. 1H NMR spectroscopic analysis shows that these water molecules interact with the electronegative oxygen atoms of the oxyethylene (OE) units of TX-100 through hydrogen-bonding interactions, and the electronegative oxygen atoms of the water molecules attract the electropositive imidazolium rings of [bmim][BF4]. Hence, the water molecules are like a glue that stick the IL and OE units more tightly together and thus make the microemulsion system more stable. Considering the unique solubilization behavior of added water molecules, the IL/O microemulsion system may be used as a medium to prepare porous or hollow nanomaterials by hydrolysis reactions.
Co-reporter:Na Li, Jie Liu, Xueyan Zhao, Yan’an Gao, Liqiang Zheng, Jin Zhang, Li Yu
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2007 Volume 292(2–3) pp:196-201
Publication Date(Web):15 January 2007
DOI:10.1016/j.colsurfa.2006.06.023
An ionic liquid (IL) surfactant, 1-dodecyl-3-methylimidazolium hexafluorophosphate (C12mimPF6) can form the inclusion complexes (ICs) with β-cyclodextrin (β-CD). The surface tension measurements revealed that there were two kinds of inclusion formations, 1:1 and 1:2 (β-CD/IL) stoichiometry for β-CD-C12mimPF6 ICs. The inclusion complexation interaction was further confirmed by FT-IR spectra. The inclusion compound was also characterized by Powder X-ray diffraction (XRD), 13C CP/MAS NMR, 2D 1H-1H COSY and TGA. The results showed that the host–guest system presented a channel type structure and each glucose unit of β-CD was in a similar environment. Only the tails of C12mimPF6 were included into the cavity of β-CD. The formation mechanism of the β-CD-C12mimPF6 was also discussed. It was suggested that hydrophobicity played a crucial role in supporting the formation of β-CD-C12mimPF6 ICs and hydrogen bonding was dispensable to maintain the channel type crystal structure. The weak hydrophobic driven force made the β-CD-C12mimPF6 unstable, which was reflected by TGA curves. In addition, possible inclusion structures of β-CD-C12mimPF6 were speculated.
Co-reporter:Yanan Gao, Suqing Wang, Liqiang Zheng, Shuaibing Han, Xuan Zhang, Deming Lu, Li Yu, Yongqiang Ji, Gaoyong Zhang
Journal of Colloid and Interface Science 2006 Volume 301(Issue 2) pp:612-616
Publication Date(Web):15 September 2006
DOI:10.1016/j.jcis.2006.05.010
Nonaqueous ionic liquid (IL) microemulsion consisting of IL, 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4), surfactant TX-100, and toluene was prepared and the phase behavior of the ternary system was investigated. Electrical conductivity measurement was used for investigating the microregions of the nonaqueous IL microemulsions. On the basis of the percolation theory, the bmimBF4-in-toluene (IL/O), bicontinuous, and toluene-in-bmimBF4 (O/IL) microregions of the microemulsions were successfully identified using insulative toluene as the titration phase. However, this method was invalid when conductive bmimBF4 acted as the titration phase. The microregions obtained by conductivity measurements were further proved by electrochemical cyclic voltammetry experiments. The results indicated that the conductivity method was feasible for identifying microstructures of the nonaqueous IL microemulsions.Nonaqueous ionic liquid microemulsion consisting of 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4), TX-100, and toluene were prepared and the phase behavior was investigated. Electrical conductivity was used to identify the microregions of the microemulsion on the basis of percolation theory. The data were further proved by the experiments of cyclic voltammetry.
Co-reporter:Xue-Yan Zhao, Quan Cao, Li-Qiang Zheng, Gao-Yong Zhang
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2006 Volume 281(1–3) pp:67-73
Publication Date(Web):15 June 2006
DOI:10.1016/j.colsurfa.2006.02.051
Gelatin-containing microemulsion-based organogels (MBGs) composed of isopropyl myristate (IPM), AOT, Tween85 and H2O, loaded with and without a model drug (butenafine hydrochloride), have been prepared and characterized by rheological measurements and environmental scanning electron microscope (ESEM). The effects of gelatin and butenafine hydrochloride on the rheological properties and microstructures of the MBGs were investigated systematically. Transparent and homogeneous MBGs could be formed when the concentration of gelatin in the selected W/O microemulsion is in the range of 7.0–12.0 wt%. The rheological properties such as the yield stresses (σy), storage and loss moduli (G′, G″) of the MBGs samples increased and the network structures of the MBGs became more compact with increasing the concentration of gelatin in the formulations. Furthermore, the addition of butenafine hydrochloride to the MBGs could weaken the interconnected network structures of the MBGs systems. Namely, when the concentration of butenafine hydrochloride was lower than 0.5 wt%, the samples are still microemulsion gels. These results show that the MBGs can be used as potentially transdermal drug delivery vehicles.
Co-reporter:Yan'an Gao Dr.;Jin Zhang;Xinwei Li;Hongyan Xu;Xueyan Zhao;Li Yu Dr.
ChemPhysChem 2006 Volume 7(Issue 7) pp:1554-1561
Publication Date(Web):21 JUN 2006
DOI:10.1002/cphc.200600120
The ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4) forms nonaqueous microemulsions with p-xylene, with the aid of the nonionic surfactant TX-100. The phase behavior of the ternary system is investigated, and three microregions of the microemulsions—ionic liquid-in-oil (IL/O), bicontinuous, and oil-in-ionic liquid (O/IL)—are identified by conductivity measurements, according to percolation theory. On the basis of a phase diagram, a series of IL/O microemulsions are chosen and characterized by dynamic light scattering (DLS). The size of aggregates increases on increasing the amount of added polar component (bmimBF4), which is a similar phenomenon to that observed for typical water-in-oil (W/O) microemulsions, suggesting the formation of IL/O microemulsions. The microstructural characteristics of the microemulsions are investigated by FTIR and 1H NMR spectroscopy. The results indicate that the interaction between the electronegative oxygen atoms of the oxyethylene (OE) units in TX-100 and the electropositive imidazolium ring may be the driving force for the solubilization of bmimBF4 into the core of the TX-100 aggregates. In addition, the micropolarity of the microemulsions is investigated by using methyl orange (MO) as a UV/Vis spectroscopic probe. A relatively constant polarity of the microemulsion droplets is obtained in the IL microemulsion. Finally, a plausible structure for the IL/O microemulsion is presented.
Co-reporter:Zhining Wang, Liqiang Zheng, Tohru Inoue
Journal of Colloid and Interface Science 2005 Volume 288(Issue 2) pp:638-641
Publication Date(Web):15 August 2005
DOI:10.1016/j.jcis.2005.03.021
The effect of sucrose on the structure of molecular assemblies formed in an MO/H2O mixture has been studied using a small-angle X-ray scattering method. It was found that the phase transition Ia3d → Pn3m → HII occurs with increased sucrose concentration in the mixture with the composition 70 wt% MO at 20 °C. This structural change induced by sucrose addition would be ascribed to a cosmotropic property of sucrose, which leads to the dehydration of the MO head group and hence causes a decrease in the effective area occupied by the MO molecule at the polar/apolar interface, which facilitates the formation of molecular assemblies with a high curvature for the reversed liquid-crystal mesophase.
Co-reporter:Shui Ling-Ling;Wang Zhi-Ning;Zheng Li-Qiang
Chinese Journal of Chemistry 2005 Volume 23(Issue 3) pp:
Publication Date(Web):4 APR 2005
DOI:10.1002/cjoc.200590245
Monoglyceride (MO) can form various liquid crystalline phases spontaneously in the presence of various amount of water at room temperature. The appropriate compositions from binary phase diagram of MO/H2O were selected to form cubic phases. The selected systems were studied at different salt concentrations and pH value using rheological methods. There was a weak effect of salt on viscoelastic properties of cubic phases formed from MO/H2O system. Hexagonal phase was formed when pH value was decreased or increased. The viscoelasticity of cubic phases was different from that of hexagonal liquid crystals. Rheological properties of MO/H2O cubic phases were stable at pH and salt concentration similar to physiological condition.
Co-reporter:Lü Feng-Feng;Zheng Li-Qiang;Gao Yan-An;Li Gan-Zuo;Tong Zhen-He
Chinese Journal of Chemistry 2005 Volume 23(Issue 8) pp:
Publication Date(Web):10 OCT 2005
DOI:10.1002/cjoc.200590957
The equilibrium and dynamic surface tension (DST) of the novel cationic surfactant, 3-(p-nonylphenoxy)-2-hydroxylpropyl trimethyl ammonium bromide, abbreviated as RTAB, were studied. The effect of sodium halide such as NaCl, NaBr and NaI on the DST behavior of the RTAB solution below its CMC was studied in detail. Due to the preferential adsorption, the effect of hydration and salting out, the ability to reduce the DST values at the same concentration was in the order of NaI>NaBr>NaCl. Attributed to its high surface activity, the equilibrium time of the DST of the surfactant solution was insensitive to the ionic strength.
Co-reporter:Ling-Ling Shui, Pei-Zhi Guo, Feng Chen, Gui-Ying Xu, Li-Qiang Zheng
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2005 Volume 256(Issue 1) pp:85-90
Publication Date(Web):1 April 2005
DOI:10.1016/j.colsurfa.2004.09.018
Monoglyceride (MO) has the ability to form various liquid crystalline phases spontaneously in the presence of various amount of water at room temperature. The appropriate compositions from binary phase diagram of monoglyceride/water were selected to form the cubic phase. Various systems were studied at different Iopamidol concentrations using rheological method. It was revealed that the viscoelastic properties went through three regions with increasing the concentration of Iopamidol. When the concentration of Iopamidol was higher than 3.97 wt.%, the viscoelastic properties were increased, for the phase structure parameter was decreased which led to the more compact structure. The lipid bilayer would be attenuated or disrupted when the concentration of Iopamidol reached to 9.98 wt.%, for the viscoelastic properties of the system was decreased.
Co-reporter:Xinpei Gao, Fei Lu, Bin Dong, Aoli Wu, Na Sun and Liqiang Zheng
Journal of Materials Chemistry A 2016 - vol. 4(Issue 34) pp:NaN13323-13323
Publication Date(Web):2016/07/29
DOI:10.1039/C6TA05223A
In this study, we present a facile method to construct highly ordered and well-defined ionic channels in anion-exchange membranes (AEMs) through in-phase photopolymerization of liquid crystals (LCs). Hexagonal and lamellar LC samples were prepared by the self-organization of polymerizable amphiphilic imidazolium-based ionic liquids. The preservation of LC nanostructures in the obtained polymeric membranes was confirmed by the combination of small-angle X-ray scattering (SAXS), polarized optical microscope (POM), and scanning electronic microscopy (SEM) measurements. Phase separations of LCs at the molecular level provided highly ordered and well-defined ionic channels for efficient anion conduction and meanwhile maintained a strong hydrophobic domain to suppress the swelling degree. The membranes synthesized in the present work provide a promising model system for understanding the idea of constructing ionic highways in AEMs through self-organization.
Co-reporter:Na Li, Shaohua Zhang, Liqiang Zheng, Bin Dong, Xinwei Li and Li Yu
Physical Chemistry Chemical Physics 2008 - vol. 10(Issue 30) pp:NaN4377-4377
Publication Date(Web):2008/06/19
DOI:10.1039/B807339B
The aggregation behavior of long-chain ionic liquids 1-alkyl-3-methylimidazolium bromide (CnmimBr) in another ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF4), was studied for the first time. Surface tension measurements revealed that aggregates are formed by CnmimBr, and freeze fracture transmission electron microscopy (FF-TEM) observations suggested the aggregates are spheres with a size much larger than traditional micelles. The sizes of the aggregates were further confirmed by dynamic light scattering (DLS) measurements.
Co-reporter:Mingwei Zhao and Liqiang Zheng
Physical Chemistry Chemical Physics 2011 - vol. 13(Issue 4) pp:NaN1337-1337
Publication Date(Web):2010/11/23
DOI:10.1039/C0CP00342E
The micellization of the ionic liquid N-alkyl-N-methylpyrrolidinium bromide (CnMPB, n = 12, 14 and 16) in aqueous solutions was investigated by surface tension measurements, electrical conductivity and static luminescence quenching. The effectiveness of the surface tension reduction (Πcmc), maximum surface excess concentration (Γmax) and the minimum area (Amin) occupied per surfactant molecule at the air/water interface can be obtained from the surface tension measurements at 25 °C. The critical micelle concentration (cmc) at different temperatures and a series of thermodynamic parameters (ΔG0m, ΔH0m and ΔS0m) of micellization were evaluated from electrical conductivity measurements in the temperature range of 25–45 °C. The thermodynamic parameters show that the micelle formation is entropy-driven at low temperature and enthalpy-driven at high temperature. Furthermore, the micelle aggregation number (Nagg) of CnMPB was calculated according to the Turro-Yekta method through static luminescence quenching and found that Nagg (49, 55, and 59) increased with the hydrophobic chain length of CnMPB.
Co-reporter:Tao Zhou, Xinpei Gao, Bin Dong, Na Sun and Liqiang Zheng
Journal of Materials Chemistry A 2016 - vol. 4(Issue 3) pp:NaN1118-1118
Publication Date(Web):2015/12/02
DOI:10.1039/C5TA08166A
Recently, flexible electrolytes have aroused tremendous interest due to their wide applications in flexible electronic devices, such as wearable electronics, roll-up displays, smart mobile devices and implantable biosensors. Herein, novel ionic liquids, whose both cations and anions both can be polymerized, are used to construct flexible poly(ionic liquid) hydrogel electrolytes by one-step synthesis. Originating from the ionic interactions inside the ionic liquids, these hydrogels combine strong and weak crosslinks after polymerization, which makes these hydrogels tough, stretchable, flexible and self-recoverable. Their superior mechanical properties have been certified by mechanical tests. Moreover, these poly(ionic liquid) hydrogels show extremely high ionic conductivities over 1 S m−1 at room temperature and low activation energy. Notably, their electrochemical behaviors can remain stable under different bending angles and successive bending, folding, compressing and twisting. As flexible electrolytes, these poly(ionic liquid) hydrogels give the possibility to be used in fuel cells or supercapacitors, thus, promoting the development of flexible electronic devices.
Co-reporter:Xinpei Gao, Fei Lu, Yizhi Liu, Na Sun and Liqiang Zheng
Chemical Communications 2017 - vol. 53(Issue 4) pp:NaN770-770
Publication Date(Web):2016/12/14
DOI:10.1039/C6CC08730B
The co-organization of polymerizable imidazolium-based ionic liquids and p-xylene led to the formation of a bicontinuous cubic phase with a primitive-type periodic minimal surface, and for the first time an anion exchange membrane preserving 3D interconnected ionic nano-channels was fabricated through in-phase photopolymerization of bicontinuous cubic liquid crystals.
Co-reporter:Xinpei Gao, Fei Lu, Bin Dong, Yizhi Liu, Yanan Gao and Liqiang Zheng
Chemical Communications 2015 - vol. 51(Issue 5) pp:NaN846-846
Publication Date(Web):2014/11/21
DOI:10.1039/C4CC08549C
Zwitterionic wormlike micelles with AuCl4− counterions were fabricated for the first time as the soft templates for colloidal synthesis of gold nanowire networks; gold-based alloy nanowire networks were also achieved using mixed wormlike micelles as soft templates.
Co-reporter:Lijuan Shi, Ying Wei, Nan Sun and Liqiang Zheng
Chemical Communications 2013 - vol. 49(Issue 97) pp:NaN11390-11390
Publication Date(Web):2013/10/15
DOI:10.1039/C3CC45550E
It was found for the first time that rich lamellar structures are formed by a single-tailed amphiphilic ionic liquid (IL), 1-dodecyl-3-methylimidazolium β-naphthalene sulfonate ([C12mim][Nsa]), in aqueous solutions without any additives. With increasing IL concentration, spontaneous transition from micelles to unilamellar and multilamellar vesicles, planar bilayers, and then to lamellar liquid crystals occurs.
Co-reporter:Xiu-Jie Yang, Bin Chen, Xu-Bing Li, Li-Qiang Zheng, Li-Zhu Wu and Chen-Ho Tung
Chemical Communications 2014 - vol. 50(Issue 50) pp:NaN6667-6667
Publication Date(Web):2014/05/06
DOI:10.1039/C4CC01671H
We report the first application of layered double hydroxide as a photocatalyst in the transformation of primary aromatic amines to their corresponding imines with high efficiency and selectivity by using oxygen in an air atmosphere as a terminal oxidant under light irradiation.
Co-reporter:Xinpei Gao, Fei Lu, Bin Dong, Tao Zhou, Wenfei Tian and Liqiang Zheng
Chemical Communications 2014 - vol. 50(Issue 63) pp:NaN8786-8786
Publication Date(Web):2014/06/17
DOI:10.1039/C4CC03626C
Zwitterionic vesicles with AuCl4− counterions were fabricated for the first time as the soft templates for colloidal synthesis of gold nanostructures; gold nanoplates spontaneously generated at the vesicle bilayers were observed and gold nanospheres were achieved via a stepwise reduction approach.
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