New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 16) pp:8546-8553
Publication Date(Web):2017/08/07
DOI:10.1039/C7NJ01294B
In this paper, functional dialkoxysilanes, (3-((3-chloropropyl)thio)propyl)methyldimethoxysilane, 3-((3-(dimethoxy(methyl)silyl)propyl)thio) propanoic acid, 3-methoxy-3-methyl-2,11-dioxa-7-thia-3-silatridecan-13-ol, and 3-methoxy-3-methyl-2,11,14,17,20,23,26,29,32-nonaoxa-7-thia-3-silatritriacontane, are first obtained by reacting functional alkenes with 3-(dimethoxy(methyl)silyl)propane-1-thiol in near-quantitative yields using a simple, efficient and photoinitiated thiol–ene click reaction. Then, functional polysiloxanes are synthesized from their corresponding functional dialkoxysilane monomers. This two-step method is a novel and efficient way of synthesizing functional polysiloxanes. The functional polysiloxanes show obvious fluorescence properties, which are assumed to be generated from unconventional chromophores. Furthermore, a series of copolymers (PETHs) with mercaptopropyl and polyether side chains are also obtained. They are successfully used for hydrophilic modification of a poly(styrene-b-butadiene-b-styrene) triblock copolymer. The PETH-based blue-light-emitting silicone elastomer is synthesized first via a thiol–ene click reaction, and it exhibits wonderful hydrophilicity, which may be useful in biomedical fields.
New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 5) pp:1997-2003
Publication Date(Web):2017/02/28
DOI:10.1039/C6NJ03386E
Thermo-responsive polysiloxanes (TRPSis) were synthesized by the catalyst-free aza-Michael addition of poly(aminopropylmethylsiloxane) to N-isopropyl acrylamide. The TRPSis exhibited a lower critical solution temperature (LCST) in water and an upper critical solution temperature (UCST) in several non-aqueous solvents (e.g., acetonitrile, ethylene carbonate, ethyl acetate, butyl acetate, and their mixed solvents). Additionally, the phase separation behaviour of the TRPSis transformed from LCST-type to UCST-type in several water–organic mixed solvents (e.g. water–acetonitrile and water–ethylene carbonate) as the water content decreased. At high water content, the LCST of the TRPSis increased upon the addition of organic solvents (ethanol, acetonitrile, and ethylene carbonate) and the UCST decreased when water was added to the organic solvents, indicating that the LCST and UCST of the thermo-responsive polymers were caused by the synergistic effect of hydrogen bonding and compatibilization. The UCST of the TRPSis shows distinct tendencies using acetonitrile–ethylene carbonate or acetonitrile–ethyl acetate as solvents. In the former case, higher UCST values were observed in the mixed solvent than in their pure one, while lower UCST values were obtained in mixed solvents in the later case. The Hansen solubility parameter was applied to explain the phenomenon and reveal the relationship between the phase separation mechanism of the TRPSis and the solubility parameter of the solvents quantitatively. The smart TRPSis could serve as promising candidates for the all-in-one application of intelligent catalysts for extraction in non-aqueous conditions.
In this study, reversible silicone elastomers were successfully developed by light-triggered dimerization and heat depolymerization of the anthryl groups. Polysiloxanes with anthryl groups were prepared from poly(aminopropylmethylsiloxane) (PAPMS) with electron-donating (9-anthracenylmethyl acrylate) and electron-withdrawing (anthracene-9-carboxylic acid) units. The cross-linking networks were formed with the via 4π–4π photo-cycloadditions of the anthryl groups upon the UV light excitation (365 nm). 9-Anthracenylmethyl acrylate or anthracene-9-carboxylic acid efficiently dimerized through the photodimerization of the anthryl groups in the organic solvents, which was proven by UV-vis spectra, NMR spectra, and LC/MS. The covalent bonds between pendant anthryl groups were cleaved after heating at 120 °C. Furthermore, repeatable dimerization–depolymerization conversion was confirmed. In addition, for the first time, we found that the sunlight can also initiate the cycloaddition, which was “greener” and more environment-friendly. The green luminescence was observed from the PAPMS-1 film instead of the quenching effect caused by aggregation after the cycloaddition. Thus, a colorful UV-light emitting diode (LED) cell was obtained by coating the films on the commercially available LED cell.
High-molecular-weight poly[(aminopropyl)methylsiloxane-co-dimethylsiloxane] (P2) and poly[(aminoethylaminopropyl)-methylsiloxane-co-dimethylsiloxane] (P3) were synthesized through base equilibration of 3-aminopropylheptamethylcyclo-tetrasiloxane or N-β-aminoethyl-γ-aminopropylheptamethylcyclotetrasiloxane with octamethylcyclotetrasiloxane. These materials were crosslinked with oligo[(acryloxypropyl)methylsiloxane-co-dimethylsiloxane] (AP-PDMS) via an aza-Michael reaction to produce novel silicone rubbers. Diaddition and triaddition reactions occurred between the aminopropyl groups of P2 and the aminoethylaminopropyl groups of P3 with the acyl groups of AP-PDMS. This led to the higher modulus of novel silicone rubbers prepared via “tension spring-type crosslinking” compared with that of the silicone rubber prepared from poly[(piperazinylpropyl)methylsiloxane-co-dimethylsiloxane] (P1) via monoaddition reaction. Crosslinking mechanism was proven by solid-state 13C NMR and Fourier transform infrared spectroscopy. Curing characteristics were measured through cure curves conducted on rheometry. The postcure conditions and the ratio of crosslinkers used were investigated in detail. Analysis of mechanical properties showed that tension spring-type crosslinking improved the modulus of silicone rubber based on P2 or P3.
New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 23) pp:14545-14550
Publication Date(Web):2017/11/20
DOI:10.1039/C7NJ03313C
A facile synthesis of a series of polysiloxane-based ionic liquids (PNLs) is reported for the first time via straightforward thiol–ene reaction with high yield using three kinds of imidazolium ionic liquid monomers bearing a halide group and poly[(mercaptopropyl)methylsiloxane]. Unexpectedly, PNLs exhibit heterogeneous physical properties with the change of the modification molar ratio; meanwhile, their film-forming properties are well discussed. Furthermore, strong blue photoluminescence caused by the S→Si coordination bond and interesting self-assembly behavior in selected solvents were observed.
New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 23) pp:14498-14504
Publication Date(Web):2017/11/20
DOI:10.1039/C7NJ03177G
Two kinds of thermo- and photo-dual-responsive polysiloxanes (DRPSs) with functional pendent groups, N-isopropyl amides and azobenzene (Azo) or salicylideneaniline (SA), were synthesized through a facile, effective, and catalyst-free aza-Michael addition of poly(aminopropylmethyl-siloxane) with N-isopropyl acrylamide and N-azobenzene acrylamide or N-salicylaldehyde acrylamide. The chemical structrures of DRPSs were systematically characterized using FT-IR, H NMR and UV-Vis spectroscopy. The as-prepared DRPSs with lower Azo or SA contents exhibited lower critical solution temperature (LCST)-type phase transition in water, which is reversible and can be controlled by temperature and UV light. The effects of Azo and SA contents on the responsive properties of DRPSs are examined in detail. The LCST decreased with the increasing Azo or SA content. Once the content of Azo or SA reached up to 5.7% or 8.2%, respectively, DRPSs could not be dissolved in water even in an ice bath. Higher values of the LCST were measured after irradiation of the polymer solutions due to the higher polarity of cis-Azo and keto-SA conformation, induced by irradiation. The differences in cloud points between the irradiated and the non-irradiated DRPS aqueous solutions increased up to 3.4 °C and 9.8 °C when combined with 3.8% Azo and 5.8% SA units, respectively.
Co-reporter:Hua Wang, Yan Liang, Huanling Xie, Haifeng Lu, Shigui Zhao and Shengyu Feng
Journal of Materials Chemistry A 2016 vol. 4(Issue 4) pp:745-750
Publication Date(Web):16 Dec 2015
DOI:10.1039/C5TC03344F
In this paper, two new organic dyes derived from 1,8-naphthalimide and dendritic polyphenyl were designed and synthesized. Both the dyes exhibited unique aggregation-enhanced emission enhancement properties in methanol/water mixtures. The traditional fluorescent materials 1,8-naphthalimides were successfully transformed to AIE-active materials based on the dendritic polyphenyl structure. Furthermore, NPI-Ph and NPI-Si displayed excellent optical properties, such as solvent-induced emission changes from deep blue to light green, and the sensitive fluorescence response to nitroaromatic explosives. Interestingly, an unexpected SiMe3 effect was found in the two dyes: the SiMe3-containing compound NPI-Si exhibited remarkably enhanced optical properties compared with the non-SiMe3 compound NPI-Ph such as a wider color-tunable range and higher sensitivity for the fluorescence detection of nitroaromatic explosives. The dendritic polyphenyl strategy and the SiMe3 effect reported in this work will provide guidance to the design of AIE-active molecules and fluorescent materials for detecting nitroaromatic explosives.
Co-reporter:Xuefeng Wang, Lichao Xu, Dan Mu, Hua Wang and Shengyu Feng
RSC Advances 2016 vol. 6(Issue 28) pp:23335-23339
Publication Date(Web):22 Feb 2016
DOI:10.1039/C6RA00270F
In this study, two series of polyphenyl and silicon-containing dendritic derivatives were designed and investigated. Unlike the traditional aggregation-caused quenching molecules, all the compounds exhibited aggregation-induced emission properties. The silicon-containing derivatives exhibited higher fluorescence than the polyphenyl compounds in the aggregate states. These derivatives also showed visible blue light in contrast to the colorless emission of the polyphenyl compounds. Whether the silicon atom is in the core structure or peripheral substitute position, all the silicon-containing compounds showed the same result. Fluorescence enhancement and color adjustment caused by the Si atom resulted from the “silicon effect”.
A series of aminopropyl-modified silica (APS) with different amine contents was prepared and, subsequently, used as cross-linkers of polysiloxane containing γ-chloropropyl groups (CPPS) to prepare heat-curable silicone rubber (MCSR). The dispersion of APS in polysiloxane matrix was studied by scanning electron microscopy. The curing characteristics, mechanical and thermal properties of the MCSR were analyzed by a rheometer, mechanical testing and thermal gravimetric analysis (TGA), respectively. The effects of the silica (TS530) content and the molar ratio of APS/CPPS on the curing characteristics were studied. The influence of the amounts of TS530 and APS, and the kind of APS, on the comprehensive mechanical properties of MCSR is discussed. The optimized conditions to prepare MCSR were obtained as follows: the amount of TS530, 55 parts per hundreds of polysiloxane in weight; the molar ratio of [NH]/[γ-chloropropyl], 1.5: 1; and the amount of amino groups on the surface of APS, 0.65 mmol/g. Additionally, TGA results show that MCSR has high thermal stability.
•The synthesis of functional polysiloxanes containing chloromethyl groups.•The thermal degradation behaviors were investigated.•Isoconversional methods were utilized to determine the kinetic parameters.Functional polysiloxanes containing chloromethyl groups, namely, α, ω-Trimethylsiloxy-poly(methylchloromethyl)siloxane (PCMS) and α, ω-Trimethylsiloxy-poly(dimethyl-methylchloromethyl)siloxane (PDCMS), were synthesized in this work. The thermal degradation behaviors of the two functional polysiloxanes were investigated through thermogravimetric analysis (TGA) in nitrogen atmosphere. The two functional polysiloxanes exhibited more than two degradation stages in the temperature range of 30 °C–800 °C. The kinetic parameters of the thermal degradation of PCMS and PDCMS were determined with isoconversional methods, including Friedman and modified Kissinger–Akahira–Sunose (KAS) proposed by Starink.
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2016 Volume 509() pp:48-55
Publication Date(Web):20 November 2016
DOI:10.1016/j.colsurfa.2016.08.086
•The organic salts affect the aggregation and surface activity of cationic silicone surfactant.•Spherical-like structured aggregates were obtained in all mixed solutions may have potential applications in many fields.•The adsorption of Si4pyrCl at the interface is stronger than the aggregation in solution.In this study, we synthesized the cationic silicone surfactant tri-(trimethylsiloxy)silylpropylpyridinnium chloride (Si4pyrCl). We then systematically investigated the effects of organic salts such as sodium acetate, sodium oxalate, sodium citrate, sodium benzoate, and sodium salicylate on the aggregation behavior of Si4pyrCl in aqueous solution through surface tension and electrical conductivity analyses, dynamic light scattering (DLS), and transmission electron microscopy (TEM). The addition of organic salts promoted surfactant aggregation. The aggregation ability was observed to be in the following order: s sodium salicylate > sodium benzoate > sodium citrate > sodium oxalate > sodium acetate. The measurement of electrical conductivity shows that the micellization of Si4pyrCl in aqueous solution is spontaneous. Several spherical-like aggregates with a diameter of approximately 500 nm were observed via TEM. The diameter distribution was determined through DLS. This work will be of great significance for the understanding of cationic silicone surfactants and their applications in industrial production.The Figure shows the surface tension curves of Si4pyrCl with sodium acetate at different concentrations. The CMC values of Si4pyrCl decrease in the presence of organic salts and it drops with the increasing of the ionic strength.
The increasing pursuit of biocontained elastic materials led the investigation of the potential use of the monoterpene limonene in film synthesis via thiol–ene reaction. Poly[(mercaptopropyl)methylsiloxane] (PMMS) is first synthesized. By controlling the molar ratio of PMMS and functional monomers, such as polyethylene glycol allyl methyl ether or rhodamine-B, PMMS is partially functionalized while leaving spare mercapto groups that could be further used as cross-linking sites. On the basis of the functionalized PMMS, novel transparent silicone luminescent films with hydrophilic tunable properties are prepared by natural-sunlight-triggered thiol–ene “click” chemistry by using d-limonene as a cross-linker. Their structures and properties are thoroughly characterized. Transparent luminescent films are coated on commercially available UV-light emitting diode (LED) cell from solution medium followed by an in situ cross-linking step; a colorful LED cell is obtained through this facile and efficient method. The UV-LED coated by films show very intense photoluminescence under normal visible light or the light is on, and has very high coloric purity.
Co-reporter:Dan Mu, Jian-Quan Li and Sheng-Yu Feng
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 19) pp:12492-12499
Publication Date(Web):07 Apr 2015
DOI:10.1039/C5CP00561B
Twelve poly(ethylene oxide)-block-poly(methyl methacrylate) (PEO-b-PMMA) copolymers with lipid-like structures were designed and investigated by MesoDyn simulation. Spherical and worm-like micelles as well as bicontinuous, lamellar and defected lamellar phases were obtained. A special structure, designated B2412, with two lipid structures connected by their heads, was found to undergo four stages prior to forming a spherical micelle phase. Two possible assembly mechanisms were found via thermodynamic and dynamic process analyses; namely, the fusion and fission of micelles in dynamic equilibrium during the adjustment stage. Water can be encapsulated into these micelles, which can affect their size, particularly in low concentration aqueous solutions. The assignment of weak negative charges to the hydrophilic EO blocks resulted in a clear effect on micelle size. Surprisingly, the largest effect was observed with EO blocks with −0.5 e, wherein an ordered perfect hexagonal phase was formed. The obtained results can be applied in numerous fields of study, including adsorption, catalysis, controlled release and drug delivery.
Co-reporter:Dan Mu, Jian-Quan Li and Sheng-Yu Feng
Soft Matter 2015 vol. 11(Issue 22) pp:4366-4374
Publication Date(Web):03 Apr 2015
DOI:10.1039/C5SM00346F
We designed twelve types of weak polyelectrolytes (i.e., PEO-b-PMMA copolymers (BCP) in multi-arm structures, where six include EO blocks as joint points and the other six have MMA blocks as joint points). All of the BCPs with EO as the joint points form disordered phases with the exception of long-chained and four-armed BCP. The main mesophases of all of the BCPs with MMA as joint points are micelle-like and bicontinuous phases. In particular, the short-chained BCP with four-arms and EO segments outside form a new phase type (i.e., crossed lamellar phase). Using MesoDyn, we provide a comprehensive representation of the micelle and crossed lamellar phase formation mechanisms based on both thermodynamic and dynamic analyses. A shear force on a micelle-like phase could promote a hexagonal columnar phase, which is a good technique for generating an ordered arrangement of nanotube arrays. Blending homopolymers with the same constituents could promote uniformity of the micelle size and decrease the polydispersity, especially for blends with a high BCP concentration, which may provide a new approach for regulating the properties of materials.
Co-reporter:Dan Mu, Jian-Quan Li and Sheng-Yu Feng
Soft Matter 2015 vol. 11(Issue 22) pp:4356-4365
Publication Date(Web):02 Apr 2015
DOI:10.1039/C5SM00438A
Combined with quantum calculations and mesoscale simulations, the self-assembly of twelve lipid-structured PEO-b-PMMA copolymers (BCPs) with six types of molecular topologies was investigated. The BCPs with MMA species as the connecting center of the other arms present ample mesoscale structures, such as micelles and lamellae or curved lamellar phases, and even macrophase separation occurs for the long-chained BCPs. The excluded volume effect of confinements helps form vesicle-like structures, which proved to be a possible method of confinement to regulate phase morphologies or segment distributions and, ultimately, the properties of materials. An analysis of the phase formation process of short-chained BCP with two hydrophilic EO segments and one hydrophobic MMA segment indicated that four stages were found in both neutral and non-neutral wall confinement, all of which present a hexagonal columnar phase. Surprisingly, when the repulsion effect of the wall to the EO segment is greater than that of the MMA segment, such BCP self assembles into a crossed columnar phase, and the intersection angle of the orientation of these two sets of cylinder arrays is 75 degrees, which can be used to produce heterogeneous nanotube arrays. For the short-chained BCP with four arms joined at MMA species and EO segments in the outer region, we found a novel method of exchanging the repulsive preference of the wall to the EO or MMA species that can control the adsorption or desorption of the lamellar phase with the interval of EO or MMA segments.
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 40) pp:26783-26789
Publication Date(Web):09 Sep 2015
DOI:10.1039/C5CP03658E
Poly(amidoamine) dendrimers are typical luminescent polymers containing unconventional chromophores. A series of novel siloxane–poly(amidoamine) (Si–PAMAM) dendrimers were synthesized and investigated in this study. Their structures and properties were determined by NMR, XPS, LC/MS, and fluorescence spectroscopy. The introduction of Si–O–Si units in Si–PAMAM changed the photophysical properties of the dendrimers. The luminescence of Si–PAMAM was associated with the aggregation of its carbonyl groups, which was caused by N → Si coordination bonds. The strong blue luminescence of Si–PAMAM was also studied in detail, and it was found to be quite different from the ethanediamine-based poly(amidoamine). Results indicated that the luminescence of Si–PAMAM could be controlled by solvents, acids, metal ions, temperature, or degree of aggregation of the carbonyl groups. Moreover, micron-sized tubes composed of Si–PAMAM molecules were generated and found in water/methanol solution.
Co-reporter:Xuefeng Wang, Jiangyan Bian, Lichao Xu, Hua Wang and Shengyu Feng
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 48) pp:32472-32478
Publication Date(Web):16 Nov 2015
DOI:10.1039/C5CP05473G
Two novel aggregation-induced emission enhancement (AIEE) molecules, namely, 3,4-diphenyl-2,5-di(2-thienyl)phenyltrimethylsilane (DPTB-TMS) and bis[3,4-diphenyl- 2,5-di(2-thienyl)phenyl]methylphenylsilane (DPTB-MPS) were designed and synthesized. The optical properties of the two silanes were completely opposite to the traditional luminescent materials. Unlike the aggregation caused quenching, they all emit faint fluorescence in the dispersed state, while emission intensity increased sharply in aggregate states. Fluorescence spectra showed that the two compounds exhibited AIEE properties and that is due to the weak π–π stacking caused by the restriction of intramolecular rotations of dye segments, particularly the –SiMe3 and thienyl groups in the aggregate state. As fluorescent (FL) probes, the fluorescence quenching behavior was further investigated. Thanks to the richer-electron thiophene groups, both compounds showed good performance in detecting nitroaromatics, especially picric acid (PA). The two AIEE FL probes exhibited better quenching efficiency in aqueous-based than in organic-based solutions. For DPTB-MPS, the addition of 80 μM nitrobenzene, 60 μM m-nitrobenzene and 40 μM PA resulted in about 50% quenching in aqueous solutions. The quenching mechanism would be electron transfer from silanes to nitroaromatics. This work provides a basis for designing organic-silanes with “abnormal” but useful optical properties and FL probes with AIEE properties for the detection of nitroaromatics.
Co-reporter:Fang Zhao, Xuping Qin and Shengyu Feng
RSC Advances 2015 vol. 5(Issue 56) pp:45113-45121
Publication Date(Web):06 May 2015
DOI:10.1039/C5RA05969K
Acrylamide-co-2-acrylamido-2-methylpropane sulfonic acid based microgel composite (MC) hydrogels with high microgel content were prepared by post crosslinking method. Acetone was used as a demulsifier and in one group of mixed solvents, which reduced the foam during nitrogen bubbling. When the microgel content was high, the microgel particles containing hydroxymethyl groups aggregated to cluster. Acetone increased the homogeneity of cluster dispersing. The microgel composite hydrogel with high microgel content was crosslinked by a cluster, which had high mechanical strength and swelling rate. Although the tensile strength and elongation decreased as the microgel content increased, the swelling rate, the size and the number of pores increased as the microgel content increased. The exciting result was that the composite hydrogel with microgel content of 12 had a porous structure. Even though it had a high crosslinking density, the hydrogel was elastic and had excellent properties. It had a tensile strength of 44 kPa and an elongation of 45% when the water content was 90%, which is considerably higher than the conventional hydrogel. It can reach swelling equilibrium in 5 hours for 3 mm3 sizes of samples, which was faster than the conventional hydrogel owing to the partly connected porous structure. These excellent properties were due to the unique structure where the hydrogel was crosslinked by a microgel cluster. It may become a new method of preparing hydrogels with a porous structure.
A novel type of highly uniform polymer microspheres, poly(urea–siloxane) (PUSs) was prepared through the precipitation polymerization of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane (APTMDS) with isophorone diisocyanate (IPDI) in H2O–acetone mixed solvent. No additives such as surfactant and initiator were used. The effects of monomer ratio, H2O/acetone ratio, and monomer concentration on the yields and morphologies of the PUSs were investigated. Results indicated that PUS sizes can be regulated from 2.14 μm to 7.11 μm by varying the monomer ratio, monomer concentration and H2O/acetone ratio. Hydrogen bonds between polyurea units, polyurea and APTMDS moieties endowed the materials with good elasticity. The structures and morphologies of the materials were characterized by FT-IR, NMR, and SEM, and the thermal properties were characterized by TGA and DSC analyses.
Materials Chemistry and Physics 2015 Volume 153() pp:161-167
Publication Date(Web):1 March 2015
DOI:10.1016/j.matchemphys.2014.12.048
•A new type of curing system for silicone rubber was studied.•The new silicone rubber has an excellent mechanical strength.•The disadvantage in the traditional curing systems can be solved in the new curing system.A new type of curing system for silicone rubber was studied for the first time by using polysiloxanes containing chloropropyl groups (CPPS) as the gum and poly(dimethyl-co-3-aminopropylmethyl) silicone oil (APPS) or poly(dimethyl-co- 3-(2-aminoethylamino)propyl) silicone oil (AEAPPS) as a crosslinker. The effect of various factors on the silicone rubber was investigated in detail. Better technical conditions were determined and the silicone rubber with excellent mechanical properties was successfully obtained. The tensile strength, tear strength, and elongation at break of the silicone rubber reach 10.25 MPa, 41.87 kN/m, 1365%, respectively. Crosslinking density of the silicone rubber was measured by toluene-swelling method to analyze the crosslinking status. The crosslinking mechanism of the new curing system was also discussed.
Reactive and Functional Polymers 2015 Volume 96() pp:14-20
Publication Date(Web):November 2015
DOI:10.1016/j.reactfunctpolym.2015.09.005
A series of high-temperature vulcanization (HTV) silicone rubber was prepared with polyamidoamine (PAMAM) dendrimers as concentrative cross-linkers and polysiloxane containing 3-chloropropyl groups (CPPS) as gums in a novel curing system. The curing, mechanical, and thermal properties of this novel HTV silicone rubber (MCSR) were studied through rheometry, mechanical testing, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The curing process was analyzed on the basis of the cure curves obtained by rheometry. The optimal conditions to prepare MCSR were determined by changing curing conditions, including cross-linker concentration, curing temperature, and postcuring temperature. MCSR exhibited a tensile strength of 9.34 MPa and a tear strength of 47.71 kN/m when the molar ratio of [3-chloropropyl]/[N–H] was 1:1.5. These excellent mechanical properties were attributed to the concentrative cross-linking effect from PAMAM dendrimers. Meanwhile, the mechanical properties slightly changed as the generation of PAMAM dendrimers increased because of steric hindrance. In addition, TGA results indicated that MCSR was thermally stable in a nitrogen atmosphere even at high degradation temperatures, such as T5 wt.% loss (MCSR-3) = 451.7 °C and T50 wt.% loss (MCSR-3) = 659.0 °C. DSC analysis revealed that a glass transition peak followed by a melt was identified for MCSR at − 160 °C to 30 °C. The experimental results showed that using PAMAM dendrimers as cross-linkers is a practical way to obtain silicone rubber with excellent properties.
Co-reporter:Yujing Zuo;Zhiming Gou;Jinfeng Cao;Zhou Yang;Haifeng Lu ; Shengyu Feng
Chemistry - A European Journal 2015 Volume 21( Issue 31) pp:10972-10977
Publication Date(Web):
DOI:10.1002/chem.201502054
Abstract
Polymerization reactions are very common in the chemical industry, however, the reaction in which monomers are obtained from polymers is rarely invesitgated. This work reveals for the first time that oxone can break the Si-O-Si bond and induce further rearrangement to yield an ordered cyclic structure. The oxidation of P1, which is obtained by reaction of 2,2′-1,2-ethanediylbis(oxy)bis(ethanethiol) (DBOET) with 1,3-divinyl-1,1,3,3-tetramethyldisiloxane (MMVi), with oxone yielded cyclic crystallized sulfone–siloxane dimer (P1-ox) after unexpected cleavage and rearrangement of the Si-O-Si bond.
Co-reporter:Hang Lu, Linglong Feng, Shusheng Li, Jie Zhang, Haifeng Lu, and Shengyu Feng
Macromolecules 2015 Volume 48(Issue 3) pp:476-482
Publication Date(Web):January 28, 2015
DOI:10.1021/ma502352x
Poly(amidoamine) (PAMAM) dendrimers and hyperbranched poly(amidoamine)s are the first reported and most investigated luminescent polymers containing unconventional chromophores. The luminescence of these compounds is associated with the N-branched tertiary amine moiety, and the oxidation of the tertiary amine is assigned to the emitting source. However, in this paper, a series of novel siloxane–poly(amidoamine) (Si-PAMAM) dendrimers were synthesized by aza-Micheal reaction, and strong blue photoluminescence was observed even with the naked eye when these compounds were excited by a UV lamp. All of these compounds were not oxidated at all. Studies on the molecular structure showed that N → Si coordination bonds existed in these compounds, and those N → Si bonds caused the aggregation of carbonyl groups which show the strong luminescence.
Co-reporter:Huanling Xie, Hua Wang, Zhen Xu, Ruijing Qiao, Xuefeng Wang, Xianming Wang, Lianfeng Wu, Haifeng Lu and Shengyu Feng
Journal of Materials Chemistry A 2014 vol. 2(Issue 44) pp:9425-9430
Publication Date(Web):17 Sep 2014
DOI:10.1039/C4TC01183J
Two fluoranthene derivatives, nonsilicon-cored 7,10-diphenylfluoranthene (DF) and silicon-cored bis(7,10-diphenylfluoranthen-8-yl)diphenylsilane (BDS), were synthesized via the Knoevenagel/Diels–Alder method. The thermal properties and fluorescence quenching behavior of the derivatives with nitroaromatic compounds were investigated. Aside from its better thermal properties, BDS also showed lower detection limit, higher sensitivity, and higher quenching efficiency in detecting nitrobenzene and m-dinitrobenzene than DF. The detection limits of BDS were 50 and 10 ppm toward nitrobenzene and m-dinitrobenzene, respectively. Moreover, the Stern–Volmer plot of BDS swiftly curved upward, suggesting a super amplification effect. This result can be attributed to the special tetrahedral structure of BDS. Thus, BDS has great potential in the detection of explosives. This work may serve as a basis for designing new organic materials with great efficiency and sensitivity in fluorescence detection.
Co-reporter:Yujing Zuo, Haifeng Lu, Lei Xue, Xianming Wang, Liang Ning and Shengyu Feng
Journal of Materials Chemistry A 2014 vol. 2(Issue 15) pp:2724-2734
Publication Date(Web):28 Jan 2014
DOI:10.1039/C3TC32382J
Novel transparent and luminescent silicone elastomers were prepared by thiol–ene chemistry. They show very intense photoluminescence under ultraviolet light and have very high coloric purity. The luminescence was obtained by complexing lanthanide ions into an N-acetyl–L–cysteine functionalized polysiloxane. The functionalized polysiloxane was prepared by an easy thiol–ene reaction and the polysiloxane was cured by thiol–ene reaction to get a crosslinking network. Their structures and properties were characterized thoroughly. The experimental results indicate complexing lanthanide ions reduced the contact angles.
Co-reporter:Hua Wang, Yan Liang, Huanling Xie, Linglong Feng, Haifeng Lu and Shengyu Feng
Journal of Materials Chemistry A 2014 vol. 2(Issue 28) pp:5601-5606
Publication Date(Web):21 May 2014
DOI:10.1039/C4TC00570H
In this paper, we report the synthesis and optical behavior of tetraphenyl benzene and its two derivatives. All the three compounds exhibited aggregation-enhanced emission (AEE) properties at a low concentration. The AEE mechanism was investigated and is due to restricted intramolecular rotation and unique packing structure. Furthermore, this kind of dendritic benzene derivatives exhibited interesting optical properties with increased concentration. Furthermore, we found a new phenomenon that the silicon-cored structure could efficiently enhance emission intensity and adjust the emission colors of dendritic benzene. The phenomenon was called “silicon-cored effect.” This effect may give some guidance to the design of new luminescent materials with AIE and AEE properties.
The photoinitiated radical-based thiol–yne click reaction provides a simple and efficient method for the formulation of diverse alkoxysilanes. Seven alkoxysilanes, namely, 1,2-bis[3-(trimethoxysilyl)propylthio]hexane (T1), 1,2-bis[3-(trimethoxysilyl)propylthio]-3-chloropropane (T2), 1,2-bis[3-(trimethoxysilyl)propylthio]-3-bromopropane (T3), trimethoxy[3-(styrylthio)propyl]silane (T4), 1,2-bis{3-[dimethoxy(methyl)silyl]propylthio}hexane (D1), 1,2-bis{3-[dimethoxy(methyl)silyl]propylthio}-3-chloropropane (D2), and 1,2-bis{3-[dimethoxy(methyl)silyl]propylthio}-3-bromopropane (D3), were synthesized by reacting alkynes with 3-mercaptopropylalkoxysilane in the presence of a photoinitiator. The thiol–yne reactions ran neatly in standard glassware under 100 W UV irradiation. The functionalized trialkoxysilanes were obtained in quantitative to near-quantitative yields with high purity. Results showed that the reaction of synthesized T4 only occurred in the first cycle, and vinyl sulfide adduct was formed with two configurations of Z and E. Moreover, the isomerization of T4 from Z to E configurations was induced under UV irradiation. T1 and D1 showed excellent photoluminescence properties. Molecular calculations were also performed to confirm the experimental results. Computational results revealed that all compounds exhibited relatively large HOMO–LUMO band gaps, making them promising candidates as host materials for emitters and hole–electron blocking materials in OLED displays. In addition, T1, T2, and T3 were selected to modify the surface properties of Si (1, 0, 0), which can then be used for further functionalization or the immobilization of polymers or biomolecules.
Co-reporter:Hua Wang, Yan Liang, Yike Wang, Huanling Xie, Linglong Feng, Haifeng Lu and Shengyu Feng
RSC Advances 2014 vol. 4(Issue 33) pp:17171-17178
Publication Date(Web):21 Mar 2014
DOI:10.1039/C3RA47751G
A series of novel silicon-cored diphenylfluoranthene derivatives was synthesized in this paper to realize efficient solid-state emission. These silicone-cored diphenylfluoranthene derivatives show better fluorescent properties in the solid state than diphenylfluoranthene because these silicone-cored derivatives exhibit weaker π–π interactions among molecules. What is more, these silicone-cored derivatives exhibit very high thermal stabilities and exceptionally high glass transition temperatures. Interestingly, one silicon-cored diphenylfluoranthene derivative exhibited similar fluorescence emission spectra in both solution and solid state, and may be the most obvious candidate for an efficient solid-state emitter.
Co-reporter:Yu-Zhong Niu, Lin Zhang, Shu-Jie Liang, Deng-Xu Wang, Sheng-Yu Feng
Chinese Chemical Letters 2014 Volume 25(Issue 11) pp:1419-1422
Publication Date(Web):November 2014
DOI:10.1016/j.cclet.2014.08.003
A series of novel ester-capped carbosilane dendrimers (G0-COOCH3–G2-COOCH3) were designed and successfully synthesized via a hybrid divergent–convergent method through a facile hydrosilylation reaction. The structures of these dendrimers were confirmed by FTIR, 1H NMR, and HRMS analyses.A series of novel ester-capped carbosilane dendrimers were designed and successfully synthesized. The structures of these dendrimers were fully confirmed by FTIR, 1H NMR, and HRMS analyses.
Journal of Organometallic Chemistry 2014 Volume 767() pp:40-45
Publication Date(Web):15 September 2014
DOI:10.1016/j.jorganchem.2014.05.039
•We synthesize a new series of silicon-centered cyano functionalized silanes.•They all display high thermal stability and strong blue fluorescence emission.•They all exhibit the linear fluorescent quenching response to diphenylamine.A series of novel tetrahedral silicon-centered cyano functionalized silanes, bis(4-cyanodiphenyl)dimethylsilane (1), bis(4-cyanodiphenyl)diphenylsilane (2), tri(4-cyandiphenyl)methylsilane (3), tri(4-cyandiphenyl)phenylsilane (4), and tetra(4-cyandiphenyl) silane (5), have been synthesized by Suzuki coupling reactions. They all display high thermal stability, and are fluorescent with strong emission in the region of violet to blue. Furthermore, 1–5 all exhibited the linear fluorescent quenching response to diphenylamine (DPA) with the high binding constants up to 1.0 × 106 M−1 in dichloromethane solution, demonstrating the potential application in DPA detection.A series of novel tetrahedral silicon-centered cyano functionalized silanes have been synthesized and well characterized. They all display strong violet-to-blue emission and exhibit obvious fluorescent quenching response to diphenylamine, indicating the excellent candidates for blue emitter materials in OLEDs and for diphenylamine detection.
Chemistry - A European Journal 2014 Volume 20( Issue 40) pp:12924-12932
Publication Date(Web):
DOI:10.1002/chem.201402746
Abstract
Side-chain vinyl poly(dimethylsiloxane) has been modified with mercaptopropionic acid, methyl 3-mercaptopropionate, and mercaptosuccinic acid. Coordinative bonding of EuIII to the functionalized polysiloxanes was then carried out and crosslinked silicone elastomers were prepared by thiol–ene curing reactions of these composites. All these europium complexes could be cast to form transparent, uniform, thin elastomers with good flexibility and thermal stability. The networks were characterized by FTIR, NMR, UV/Vis, and luminescence spectroscopy as well as by scanning electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy. The europium elastomer luminophores exhibited intense red light at 617 nm under UV excitation at room temperature due to the 5D07F2 transition in EuIII ions. The newly synthesized luminescent materials offer many advantages, including the desired mechanical flexibility. They cannot be dissolved or fused, and so they have potential for use in optical and electronic applications.
Chemistry - A European Journal 2014 Volume 20( Issue 40) pp:12945-12953
Publication Date(Web):
DOI:10.1002/chem.201402836
Abstract
The preparation of thermoresponsive drug carriers with a self-destruction property is presented. These drug carriers were fabricated by incorporation of drug molecules and thermoresponsive copolymer, poly(N-isopropylacrylamide-co-acrylamide), into silica nanoparticles in a one-pot preparation process. The enhanced drug release was primarily attributed to faster molecule diffusion resulting from the particle decomposition triggered by phase transformation of the copolymer upon the temperature change. The decomposition of the drug carriers into small fragments should benefit their fast excretion from the body. In addition, the resulting drug-loaded nanoparticles showed faster drug release in an acidic environment (pH 5) than in a neutral one. The controlled drug release of methylene blue and doxorubicin hydrochloride and the self-decomposition of the drug carriers were successfully characterized by using TEM, UV/Vis spectroscopy, and confocal microscopy. Together with the nontoxicity and excellent biocompatibility of the copolymer/SiO2 composite, the features of controlled drug release and simultaneous carrier self-destruction provided a promising opportunity for designing various novel drug-delivery systems.
Journal of Chemical & Engineering Data 2014 Volume 59(Issue 6) pp:1830-1834
Publication Date(Web):April 15, 2014
DOI:10.1021/je401118k
The micellization of two silicone ionic liquids, 1-methyl-1-[tri(trimethylsiloxy)]- silylpropylpyrrolidinium nitrate (Si4pyNO3) and 1-methyl-1-[tri(trimethylsiloxy)]- silylpropylpyrrolidinium acetate (Si4pyAc), with different counterions was systematically investigated by surface tension and electrical conductivity. Surface tension of water can be reduced almost to 20 mN·m–1 with the addition of the silicone ionic liquids, indicating that the silicone ionic liquids exhibit excellent surface activity. The critical micelle concentration (CMC) values of Si4pyNO3 are less than those of Si4pyAc. Electrical conductivity measurements show that the degree of counterion binding (β) for Si4pyNO3 is twice as large as that for Si4pyAc. Thermodynamic parameters (ΔHm0, ΔSm0, and ΔGm0) of micellization derived from electrical conductivities indicate that the micellization for both Si4pyNO3 and Si4pyAc is enthalpy-driven process. The heat capacities, Δcm,p0, are negative for the two silicone ionic liquids relating to the removal of water accessible nonpolar surfaces. The addition of sodium halides in the aqueous solution decreases CMC remarkably; however, the surface tension at CMC stays the same with the salt-free system.
Co-reporter:Hua Wang, Huanling Xie, Yan Liang, Linglong Feng, Xiyuan Cheng, Haifeng Lu and Shengyu Feng
Journal of Materials Chemistry A 2013 vol. 1(Issue 34) pp:5367-5372
Publication Date(Web):10 Jul 2013
DOI:10.1039/C3TC31097C
Well-defined organic composite nanoparticles were prepared from perylene bisimide dye and silicon-cored fluoranthene derivate molecules. The composite nanoparticles exhibited good stability and thermal properties. The fluorescence emission of the perylene bisimide dye can be efficiently enhanced in composite nanoparticles based on efficient Föster resonant energy transfer. The composite nanoparticles exhibited tunable emission colors from blue to red by changing the concentration of the perylene bisimide dye. White-light emission with CIE coordinates (0.327, 0.339) was obtained as a good candidate for applications in white optoelectronic devices.
Co-reporter:Dengxu Wang, Wenyan Yang, Liguo Li, Xian Zhao, Shengyu Feng and Hongzhi Liu
Journal of Materials Chemistry A 2013 vol. 1(Issue 43) pp:13549-13558
Publication Date(Web):04 Sep 2013
DOI:10.1039/C3TA12324C
Cubic octavinylsilsesquioxane successively reacts with different tetrahedral silicon-centered precursors containing di-, tri-, or tetrabromophenyl groups to prepare hybrid porous polymers (HPPs) via Heck reaction. The resulting materials possess high porosities with Brunauer–Emmett–Teller specific surface areas of up to 875 m2 g−1. Their porosities can be tuned by altering the number of the connecting sites of silicon-centered units. For gas storage applications, HPP-5 exhibits the following properties: a high H2 uptake of 7.76 mmol g−1 (1.56 wt%) at 77 K and 1.01 bar; a moderate CO2 uptake of 1.04 mmol g−1 (4.58 wt%) at 298 K and 1.04 bar; and a low CH4 uptake of 0.28 mmol g−1 (0.45 wt%) at 298 K and 1 bar. These results suggest that these polymers can be applied as promising materials for H2 and CO2 storage as well as the selective adsorbents of CO2 rather than CH4. These polymers are also luminescent with the maximum emission at ca. 420 nm in the solid state; therefore, they could be potentially applied as blue light-emitting materials.
Co-reporter:Hua Wang, Yan Liang, Linglong Feng, Huanling Xie, Jie Zhang, Xiyuan Cheng, Haifeng Lu, Shengyu Feng
Dyes and Pigments 2013 Volume 99(Issue 2) pp:284-290
Publication Date(Web):November 2013
DOI:10.1016/j.dyepig.2013.05.022
•A novel silicon-cored fluoranthene derivative was synthesized as a blue emitter.•A new perylene end-capped polymer was synthesized and selected as an orange emitter.•A series of luminescence was obtained by controlling the donor/acceptor ratios.•White light emission was obtained when the proper ratio was adopted.•The different energy transfer mechanisms in solution and film were investigated.A series of tunable luminescence was obtained by controlling the donor/acceptor ratios. A silicon-cored fluoranthene derivative named bis (7,10-diphenyl-fluoranthene) methylphenylsilane (BFMPS) was used as the donor and a perylene end-capped polydimethylsiloxane (PECP) was used as the acceptor for preparing the blending systems. Efficient energy transfer was detected in these unique systems, which were composed of micromolecules and fluorescence macromolecules. In particular, pure white emission was obtained when the adequate blending ratio was adopted. Further characterizations and investigations were carried out to examine the energy transfer from donor to acceptor both in solution and in solid thin films. Two different energy transfer mechanisms were deduced from the investigation of the ultraviolet absorption and luminescence spectra. Radiative energy transfer was dominant in solution while Föster resonant energy transfer was dominant in thin films.
Pseudopolyrotaxanes (POSS/CB[7]) were synthesized using octaimidazolium-based polyhedral oligomeric silsesquioxanes (POSS) and cucurbit[7]uril (CB[7]) in aqueous solution. The binding interactions were monitored by 1H NMR. Their regular octahedral morphologies were confirmed by TEM. The POSS/CB[7] was also characterized by FT-IR, thermogravimetric analysis (TGA), and elemental analysis. The TGA results show that the thermal stabilities of POSS/CB[7] can be improved by the threading of CB[7].
Preparation of POSS–min–DS, an octaimidazolium-based polyhedral oligomeric silsesquioxanes (POSS) room temperature ionic liquid, by an ion-exchange reaction between POSS and sodium dodecyl sulfate was reported. Octaimidazolium-based POSS was synthesized with more than 98% yield within 3 h. POSS–min–DS and octaimidazolium-based POSS were confirmed by 1H, 13C, and 29Si NMR, FT-IR and elemental analysis.
Co-reporter:Lei Xue, Dengxu Wang, Zhizhou Yang, Yan Liang, Jie Zhang, Shengyu Feng
European Polymer Journal 2013 Volume 49(Issue 5) pp:1050-1056
Publication Date(Web):May 2013
DOI:10.1016/j.eurpolymj.2013.01.017
Polysiloxanes are unique hybrid inorganic and semi-inorganic polymers that have a wide range of applications in industries. In this study, we report a facile and efficient approach to prepare functional polysiloxanes via thiol–ene reaction. The functional polysiloxanes were characterized and confirmed by 1H NMR, 13C NMR, FT-IR, GPC, TGA and DSC. Influence of thiol and vinyl structure over reaction rate was analyzed. The proportion of α- and β-addition product was also determined by 1H NMR. GPC analysis showed that the molecular-weight distribution of polysiloxanes cannot be disturbed in thiol–ene reaction.Graphical abstractHighlights► Various functional polysiloxanes were prepared via thiol–ene reaction under high-intense ultraviolet (UV) condition. ► This modification reaction was carried out under a mild condition without metal catalysts. ► The resulting functional polysiloxanes maintained the excellent thermal stability of traditional polysiloxane.
Co-reporter:Yuanzhi Yue;Yan Liang;Hua Wang;Linglong Feng;Haifeng Lu
Photochemistry and Photobiology 2013 Volume 89( Issue 1) pp:5-13
Publication Date(Web):
DOI:10.1111/j.1751-1097.2012.01199.x
Abstract
Novel luminescent silicone hybrids (LSHs) containing lanthanide ions were prepared via different sol–gel processes. The precursor, dimethyl ester-functionalized silane, was synthesized via a facile amino-ene reaction. The coordinated assembly of the ester ligands and lanthanide ions (Eu3+, Tb3+ and Dy3+) occurred. The ester ligands were immobilized onto the Si-O network backbone during the preparation of the silicone hybrid materials. The particle size can be controlled to ca 50 nm by adjusting the solvent ratio. The obtained materials were characterized by Fourier transform infrared, 1H nuclear magnetic resonance spectroscopy (NMR), 13C NMR, 28Si NMR, X-ray diffraction, X-ray photoelectron spectroscopy, thermogravimetric analysis, high-resolution scanning electronic microscopy and luminescent (excitation and emission) spectroscopy. The coordination state and photophysical performance of the compounds were studied in detail. The terbium- and europium-containing materials show sharp green and red emissions, respectively, which indicate that efficient intramolecular energy transfer took place in these LSHs.
Understanding the thermal rearrangement mechanism of chloromethylsilane in the presence of Lewis acids is particularly important in industrial applications. In this study, the thermal rearrangements of chloromethylsilane under the catalysis of AlCl3 and BF3 were studied on the basis of density functional theory (DFT) at the B3LYP/6-311G (d, p) level. The structures of the reactants, transition states and products were located and fully optimized. The geometries of various stationary points and the harmonic vibrational frequencies were calculated at the same levels. The reaction paths were investigated and confirmed by intrinsic reaction coordinate (IRC) calculations. The results showed that the thermal rearrangement of chloromethylsilane in the presence of a Lewis acid occurred via two pathways (MX3-1 and MX3-2). Only pathway MX3-1 had a catalytic effect. The determining factor of the reaction activation energies and rates was the formation of the transition state in each reaction. Among all the reactions, the Al atom could form an approximate tetrahedral coordination with four Cl atoms, resulting in the lowest energy barrier. The kinetic and thermodynamic calculations also proved this result.
Hybrid nanocomposites were prepared via solution blending of octaphenethyl POSS into novolac resin. The resulted hybrid blends were investigated by Fourier-transformed infrared spectra (FTIR), polarized optical microscopy (POM), wide X-ray diffraction and differential scanning calorimetry (DSC). FTIR results showed that there existed intermolecular hydrogen bond between the hydroxyl groups of the phenolic resin and POSS siloxane groups, which could promote POSS to disperse well in the polymer matrix up to 20 wt% POSS loading. At higher POSS loading, POSS would aggregate and lead to macrophase separation, which was demonstrated by POM, DSC and WXRD. Finally, hexamethylene tetramine was used to cure the novolac blends to form hybrid network phenolic nanocomposites. Dynamic mechanical analysis results showed that the storage modulus of the hybrid networks was improved up to 20 wt% POSS loading; the Tg was increased with increasing POSS content and higher than that of the control phenolic resin except that 5 wt% POSS loading. Thermo gravimetric analysis showed that the thermal stability of hybrid networks was also enhanced with the incorporation of POSS.
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2013 Volume 417() pp:146-153
Publication Date(Web):20 January 2013
DOI:10.1016/j.colsurfa.2012.10.041
Three cationic silicone surfactants, 1-methyl-3-[tri-(trimethylsiloxy)]silylpropyl-imidazolium chloride (Si4mimCl), (2-hydroxyethyl)-N,N-dimethyl-3-[tri-(trimethylsiloxy)]silylpropylammonium chloride (Si4mam-OHCl), 1-methyl-1-[tri-(trimethylsiloxy)]silylpropylpyrrolidinium chloride (Si4pyCl), with the same hydrophobic group and different headgroups were synthesized. Their aggregation behavior in aqueous solution was systematically investigated by surface tension, electrical conductivity, and steady-state fluorescence. Surface tension of water can be reduced almost to 20 mN m−1 with the addition of the cationic silicone surfactants. This result indicates that all the three surfactants exhibit remarkable surface activity. Because of the effect of the headgroups, the critical micelle concentrations (CMC) values increase following the order Si4pyCl < Si4mimCl < Si4mam-OHCl, and Si4pyCl packs more tightly at the air/water interface compared with Si4mimCl and Si4mam-OHCl. Electrical conductivity measurements show that all the three cationic silicone surfactants have low degree of counterion binding (β) and the β values for Si4pyCl and Si4mam-OHCl increase with increasing the temperature in the investigated temperature range. Thermodynamic parameters (ΔHm0, ΔSm0, and ΔGm0) of micellization indicate that the micellization for Si4mimCl in aqueous is enthalpy-driven, and that for both the Si4pyCl and Si4mam-OHCl entropy-driven.Graphical abstractAggregation behaviors of three novel cationic silicone surfactants are investigated. The figure of β–T for Si4mimCl, Si4pyCl and Si4mam-OHCl shows that the values of β for Si4pyCl and Si4mam-OHCl increase as the temperature increases.Highlights► Cationic silicone surfactants with the same hydrophobic group and different headgroups were synthesized. ► Cationic silicone surfactants have higher surface activity compared with common hydrocarbon surfactants. ► The β values for Si4pyCl and Si4mam-OHCl increase with increasing the temperature in the investigated temperature range.
Colloid and Polymer Science 2013 Volume 291( Issue 6) pp:1487-1494
Publication Date(Web):2013 June
DOI:10.1007/s00396-012-2885-6
Three cationic silicone surfactants, (2-hydroxyethyl)-N,N-dimethyl-3-[tri-(trimethylsiloxy)]silylpropylammonium chloride (Si4ACl), (2-hydroxyethyl)-N,N-dimethyl-3-[bis(trimethylsiloxy)methyl]silylpropylammonium chloride (Si3ACl), and (2-hydroxyethyl)-N,N-dimethyl-3-[bis(trimethylsilylmethyl)methyl]silylpropyl-ammonium chloride (Si3C2ACl), with the same headgroups and different hydrophobic groups were synthesized. Their aggregation behavior in aqueous solution was investigated by surface tension and electrical conductivity. The results show that all the three cationic silicone surfactants perform admirable surface activity. Because of the effect of the hydrophobic groups, the critical micelle concentration values increase following the order Si3C2ACl < Si4ACl < Si3ACl, and Si3C2ACl packs more compactly at the air/water interface compared with Si4ACl and Si3ACl. Electrical conductivity studies show that all the three cationic silicone surfactants have low degree of counterion binding. Thermodynamic parameters (\( \varDelta\;H_m^0 \), \( \varDelta S_m^0 \), and \( \varDelta G_m^0 \)) of micellization derived from electrical conductivities indicate that the micellization for both Si3C2AC and Si3ACl in aqueous solution is enthalpy-driven, and that for the Si4ACl is entropy-driven. For the heat capacities, \( \varDelta\;c_{m,p}^0 \), values are positive for Si4ACl, indicating that there is an attractive interaction between the nitrogen atom of one surfactant molecule and the oxygen atom of another surfactant molecule for Si4ACl.
Dyes and Pigments 2012 Volume 95(Issue 2) pp:260-267
Publication Date(Web):November 2012
DOI:10.1016/j.dyepig.2012.04.015
A novel polysiloxane-modified perylene derivative was designed and synthesized through the amidation reaction between aminopropyl-terminal polysiloxane and perylene tetracarboxylic diester monoimides with n-dodecyl as the alkyl chain connected to the perylene core. The synthesized compound was subjected to IR and 1H NMR. The liquid-crystalline property of the modified perylene derivative at room temperature (ranged from 27.1 °C to 61.3 °C) was characterized via differential scanning calorimetry, polarization optical microscope, X-ray powder diffraction, and small-angle X-ray scattering. The morphology of the compound was evaluated via scanning electron microscopy and atomic force microscopy in tapping mode. The static contact angle of the perylene derivative with distilled water as the test liquid was improved after modification by polysiloxane. All the measurements revealed that the polysiloxane-modified perylene derivative exhibited good thermal stability, excellent optical property, good hydrophobic property, and low temperature liquid-crystalline property. These properties may be attributed to the presence of flexible Si–O–Si chain and ordered π–π* stacking between adjacent perylene cores.Highlights► Synthesis method of polysiloxane-modified perylene derivative had high yield. ► The desired product owned excellent optical property. ► It also had hydrophobic liquid-crystalline property under room temperature. ► It had good thermal stability and can be used as high-temperature material.
Journal of Chromatography A 2012 Volume 1256() pp:213-221
Publication Date(Web):21 September 2012
DOI:10.1016/j.chroma.2012.07.049
Phenyl-ended hyperbranched carbosilane (HBC) is synthesized and immobilized onto the inner wall of a fused silica capillary column using a sol–gel process. The hybrid coating layer formed is used as a stationary phase for gas chromatography (GC) and as an adsorption medium for solid phase microextraction (SPME). Trifluoroacetic acid, as a catalyst in this process, helps produce a homogeneous hybrid coating layer. This result is beneficial for better column chromatographic performances, such as high efficiency and high resolution. Extraction tests using the novel hybrid layer show an extraordinarily large adsorption capacity and specific adsorption behavior for aromatic compounds. A 1 ppm trace level detectability is obtained with the SPME/GC work model when both of the stationary phase and adsorption layer bear a hyperbranched structure. A large amount of phenyl groups and a low viscosity of hyperbranched polymers contribute to these valuable properties, which are important to environment and safety control, wherein detection sensitivity and special adsorption behavior are usually required.
Co-reporter:Zheng Yue, Deng Xu Wang, Jing Quan Liu, Jie Zhang, Sheng Yu Feng
Chinese Chemical Letters 2012 Volume 23(Issue 8) pp:989-992
Publication Date(Web):August 2012
DOI:10.1016/j.cclet.2012.05.024
A new A-B-A type of block copolymers, polyacrylonitrile-block-polydimethylsiloxane-block-polyacrylonitrile (PAN-b-PDMS-b-PAN), which comprises two polymer blocks of different polarities and compatibilities, were synthesized for the first time via reversible addition-fragmentation chain transfer polymerization. Reaction kinetics was investigated. PAN-b-PDMS-b-PAN films were prepared by spin-coating on glass chips. Significant order on the film surface morphologies was observed.
Co-reporter:Jianjun Han, Haifeng Lu, Jie Zhang, Shengyu Feng
Materials Chemistry and Physics 2012 Volume 136(Issue 1) pp:36-42
Publication Date(Web):14 September 2012
DOI:10.1016/j.matchemphys.2012.06.015
A novel rubber composite of acrylonitrile-butadiene rubber (NBR) filled with cerium salt particles was vulcanized via in situ coordination for the first time. The resulting materials exhibit good mechanical properties. Curing characteristics analysis, differential scanning calorimetry, X-ray photoelectron spectroscopy, tensile testing, and an equilibrium swelling method were used for the characterization of the composite. The results in this paper indicate that the composite is a kind of elastomer based on the in situ coordination crosslinking interactions between the nitrile groups (–CN) of NBR and cerium ions. The mechanical properties of vulcanized cerium salt/ NBR rubber are altered when changing the sorts of cerium salt. Moreover, these materials show good irradiation resistance because of the introduction of the cerium salt.Highlights► Cerium salts were firstly used to vulcanize the acrylonitrile-butadiene rubber. ► Cerium salts act as not only crosslink agents but also reinforcing fillers in the matrix. ► These materials show good irradiation resistance and mechanical properties at same time.
The effects of γ-ray radiation on the properties of fluorosilicone rubber (FSR) were studied. The surface morphology, nuclear magnetic resonance spin–spin relaxation, as well as mechanical and dynamic mechanical properties of FSR were examined before and after γ-ray irradiation. The results showed that the crosslinking density and hardness increased after irradiation. The tensile strength, tear strength, and elongation at break decreased with increased radiation dose. The effects of the radiation on the properties of FSR were ascribed to the occurrence of degradation and crosslinking reactions. Overall, the results proved that the degradation reaction dominated over the crosslinking reaction during γ-ray irradiation.
Chinese Chemical Letters 2012 Volume 23(Issue 11) pp:1259-1262
Publication Date(Web):November 2012
DOI:10.1016/j.cclet.2012.09.012
A new β-cyclodextrin modified hyperbranched carbosilane stationary phase for gas chromatography was synthesized by substituting the OH groups of β-cyclodextrin with hyperbranched carbosilane and was coated on the inner wall of fused silica capillary column for gas chromatography. The chromatographic behaviors of the stationary phase were studied. The initial testing results showed that it possessed good separation abilities for several kinds of mixtures, such as benzenes, acrylates, ketones and alkylchlorides.
Polymer Degradation and Stability 2011 Volume 96(Issue 12) pp:2145-2151
Publication Date(Web):December 2011
DOI:10.1016/j.polymdegradstab.2011.09.014
A series of silicone resins containing silphenylene units were synthesized by a hydrolysis–polycondensation method, with methyltriethoxysilane, dimethyldiethoxysilane and 1,4-bis(ethoxydimethylsilyl)benzene. Their thermal degradation behaviours were studied by thermogravimetric analysis (TGA), differential thermogravimetry (DTG) and Fourier-transform infrared (FTIR) spectroscopy, and the effect of silphenylene units on the thermal stability of silicone resins was also investigated. Results showed that the thermal stability of silicone resins was improved by the introduction of silphenylene units into the backbone. Under nitrogen atmosphere, the temperature for maximum degradation rate of silicone resins with silphenylene units was lower compared to the pure methylsilicone resin. With the increase of silphenylene units, the amount of degradation residues increased under nitrogen atmosphere while it decreased under air atmosphere. Additionally, the short-term and long-term stability of silicone resins were also improved by the introduction of silphenylene units.
A new modified polysiloxane, perylene-containing polysiloxane (PCP), was successfully synthesized by amine-terminated polysiloxane (ATP) and 3,4,9,10-perylene tetracarboxylic dianhydride. The synthesized compound was characterized by Fourier transform infrared spectroscopy (FT-IR) and 1H nuclear magnetic resonance (1H NMR). The thermal analysis of the PCP indicates that the modified polysiloxane has outstanding thermal stability. The PCP also possesses good fluorescence property. Due to the appearance of lone-pair electrons and π bond in PCP, it could be self-assembled on iron surface and thus used in the corrosion protection area. The PCP films were characterized by EIS (electrochemical impedance spectroscopy) and SEM (scanning electron microscopy). These results indicate that the films modified by PCP could protect the iron from corrosion efficiently.
European Polymer Journal 2011 Volume 47(Issue 10) pp:1903-1911
Publication Date(Web):October 2011
DOI:10.1016/j.eurpolymj.2011.07.001
Multilayer hydrogels were prepared by frontal photopolymerization of acrylamide and 2-acrylamido-2-methylpropane sulfonic acid using hydrophilic reactive microgels (HRM) as crosslinkers instead of conventional crosslinkers. The hydrophilic microgels (HM) were prepared by inverse emulsion photopolymerization and then were chemical modified by N-methylolacrylamide (NMA) to obtain HRM with CC double bonds. The HM and HRM was characterized by dynamic light scattering measurements, SEM, TEM and FTIR, respectively. It was found that the resulting multilayer hydrogels showed high fracture strength and high tensile elongation along parallel direction. However their fracture strength and tensile elongation along perpendicular direction was very weak. The swollen multilayer hydrogels were about 1.0–2.0 mm in thickness, the maximal equilibrium swelling degree was only 30.45. The multilayer hydrogels were characterized by DSC, TEM and XRD, respectively. The swelling property and mechanical strength of some typical multilayer hydrogels were studied.Graphical abstractHighlights► Multilayer hydrogels were prepared by frontal photopolymerization. ► Hydrophilic reactive microgels (HRM) containing CC double bonds as crosslinkers. ► The multilayer hydrogels showed high mechanical strength along parallel direction. ► The multilayer hydrogels were very weak along perpendicular direction.
The reaction of dimethyldi(4-N,N-dimethylaminophenyl)silane (1) and chloroplatinic acid hexahydrate was carried out in acetone (ace). A complex salt, [H(dma)]2(PtCl6)·0.5ace (2·0.5ace) (dma = N,N-dimethylphenylamine), was obtained and characterized by Single-crystal X-ray diffraction. At the same time, byproducts (4-dimethylaminophenyl)dimethylsilanol (3), dma, 4-(dimethylphenyl silyl)-N,N- dimethylaniline (4), and 1,3-Bis(4-(dimethylamino)phenyl)-1,1,3,3-tetra-methyldi- siloxane (5), structurally confirmed by FT-IR, 1H NMR, 13C NMR, 29Si and ESI MS NMR spectra, were found. This indicates that the cleavages of Si–C and C–N bonds of 1 in the reaction occurred. In addition, the reaction mechanisms were referred.The reaction of dimethyldi(4-N,N-dimethylaminophenyl)silane (1) and chloroplatinic acid hexahydrate was carried out in acetone (ace). A complex salt, [H(dma)]2(PtCl6)·0.5ace (2·0.5ace) (dma = N,N-dimethylphenylamine), was obtained and characterized by Single-crystal X-ray diffraction. Its supramolecular structure was built through the hydrogen bond self-assembly, with a combination type in the molecule structure where anions and cations are staggered with respect to each other. The existence of dma indicates the cleavage of Si–C bond of 1 in the reaction occurred.Research highlights► Complex salt [H(dma)]2(PtCl6)·0.5ace (2·0.5ace) was prepared unexpectedly. ► The crystal structure of 2·0.5ace shows the intramolecular neutralization effect. ► Proposed reaction mechanism shows the Si–C bond cleavage in common organic solvent.
Materials Chemistry and Physics 2011 Volume 129(1–2) pp:202-208
Publication Date(Web):15 September 2011
DOI:10.1016/j.matchemphys.2011.03.077
Three kinds of treated fumed silica were prepared with methylphenyldimethoxysilane (MPHTS), diphenyldiethoxysilane (DPHTS), and phenyltriethoxysilane (PHTS) as treating agents, respectively, and characterized by N2 adsorption, diffuse reflectance ultraviolet–vis spectra (DRUVS), titration and element analyzer. The results show that compared with untreated silica there are less surface hydroxyl groups retained on the treated silica, and the phenyl groups are introduced onto the silica surface. The treated silica was used as reinforcing filler for silicone rubber to investigate the resistance to irradiation of the silicone rubber obtained thereout. The mechanical properties and the average molecular weight between crosslinking points (Mc) of the silicone rubber were measured before and after irradiation. The dynamical mechanical properties of the silicone rubber were evaluated by dynamic mechanical analysis (DMA) before and after irradiation. It was found that the treated fumed silica cannot only effectively improve the radiation resistance of silicone rubber but also has excellent reinforcing effect on silicone rubber.Highlights► Three kinds of phenyl modified fumed silica are prepared. ► Phenyl modified fumed silica are used as reinforcing filler for silicone rubber. ► This is a novel effective way to improve radiation resistance of silicone rubber.
Silicone rubber composed of diverse vinyl content silicone gums blending were prepared and their mechanical properties were investigated. The silicone rubber composed of diverse vinyl content silicone gums blending whose crosslinking points were concentration distribution exhibited better tearing strength and higher tensile modulus in comparison with single vinyl content gums which were mean distribution. The average molecular weight (Mc) of the silicone rubber composed of diverse vinyl content blending are lower than that of single vinyl molar content 0.16% which was calculated by swelling equilibrium method. The viscoelastic behavior indicated the silicone rubber composed of 0.04% and 0.3% vinyl molar content gums blending possessed perfect flexibility at low temperature because it had the lowest glass transition temperature (Tg), and this sample had the largest storage modulus and loss modulus.
Co-reporter:Dengxu Wang, Haiyan He, Xiaohui Chen, Shengyu Feng, Yuzhong Niu and Daofeng Sun
CrystEngComm 2010 vol. 12(Issue 4) pp:1041-1043
Publication Date(Web):09 Nov 2009
DOI:10.1039/B910988A
Slow diffusion of AgClO44 with Me2Si [(4-(Im-1-yl)Ph]2 (BIPS) yields the crystalline complex 1 with a 3D-braided porous metal–organic framework via self-assembly of two series of 1D polymer chains through both braiding and interpenetrating. Complex 1 consists of two distinct kinds of channels with different sizes and shapes along a and b directions occupied by perchlorate anions and water molecules.
Journal of Non-Crystalline Solids 2010 Volume 356(31–32) pp:1581-1586
Publication Date(Web):1 July 2010
DOI:10.1016/j.jnoncrysol.2010.05.059
Two series of rare earth-containing luminescent silicone resins have been achieved by sol–gel method. The precursors which were modified via acylamidation reactions behave as structural molecular bridges. The silanol groups were used to form the host of silicone resin and the chromophore groups were used to exhibit the luminescence by the cooperative assembly courses with rare earth ions (Eu3+, Tb3+, and Dy3+). The modifications were determined by Fourier transform infrared (FTIR), 1H-NMR spectra and diffuse reflectance ultraviolet–visible spectra (DRUVS). Scanning electronic microscopy (SEM, micrometric scale) and X-ray diffraction studies (XRD, nanometric scale) were employed to evaluate the frameworks of silicone resin materials. Narrow-width red emission was observed in Eu (III) resin materials and green emissions were obtained in Tb (III) resin materials and Dy (III) resin materials, indicating that an efficient intramolecular energy transfer took place in these resins. Further investigations into the luminescent properties of these materials show that the luminescence in these materials is quite operative by means of the design of molecular structure.
Three density functionals, B3LYP, BB95 and MPWB1K, were adopted to investigate the geometries and spectral properties of bis(3-cyano-thienyl)-dimethylsilane, bis(2-thienyl)dimethylsilane and bis(3-thienyl)dimethylsilane, respectively. The best agreement between theoretical and experimental geometries is in the MPWB1K results; the next is in the B3LYP ones, followed by the BB95 ones. MPWB1K functionals can well predict the characteristic frequencies of most vibrational modes, except for the silylmethyl C–H and the CN bond stretching vibration. BB95 functionals can give the best electronic absorption spectra, followed by MPWB1K and B3LYP one. The CN substitution as well as the connection way between the silylene and thienyl unit exerts the significant effects on the silylmethyl C–H in-plane rocking, thienyl C–H out-of-plane and bridging C–Si–C bond asymmetry stretching vibration. The most obvious difference of the electronic absorption spectra among 1, 2 and 3 is that 1 shows three strong peaks, while 2 as well as 3 shows only one.
Journal of Photochemistry and Photobiology A: Chemistry 2010 Volume 210(Issue 1) pp:48-53
Publication Date(Web):5 February 2010
DOI:10.1016/j.jphotochem.2009.12.006
The functional precursor (PySi) was derived from the hydrosilylation reaction of methyldichlorosilane and 4-vinylpyridine, and then two series of novel luminescent hybrid materials (RE-PySi, where RE = Tb, Dy) with organic fragments covalently linked to inorganic parts were assembled by a sol–gel process, and characterized by the X-ray diffraction, scanning electron microscopy, and spectroscopy. It is found that the sol–gel treatment has an influence on the organization and microstructure of the hybrid materials, indicating that the hybrid material systems derived from different solvents exhibit different textures. The photoluminescent behavior of these chemically bonded hybrids was studied in detail. The observed green luminescence suggested that the intra-molecular energy-transfer process between the lanthanide ion and the pyridyl group takes place among these molecular-based hybrids.
To tune purposefully the electronic structures of poly(carbosilylsilanes), a theory study has been investigated using the density functional theory combined with AM1 method. Attentions were paid to the dependence of molecular geometries and absorption spectra on the backbone conformation and the various substituting groups. The strong electronegative substituents can more effectively tune the geometries and spectra of the polysilanes than the alkyl ones. Their main-chain substitutions can induce the great red-shift of the absorption spectra, and the side-chain substitutions can induce the blue-shift. The length of methylene chain in the carbosilyl groups exerts the small effect on the absorption spectra, but with the lengthening of side chain, poly(carbosilylsilanes) have a preference for the all-trans conformation with the loose helix backbone. Different from the alkyl side chain in poly(alkylsilanes), the lengthening of carbosilyl chain leads to the decrease of the positive charges of silicon backbone.
Journal of Photochemistry and Photobiology A: Chemistry 2010 Volume 214(2–3) pp:241-247
Publication Date(Web):15 August 2010
DOI:10.1016/j.jphotochem.2010.07.002
A novel A-σ-π-σ-A type of silicon-bridged compound, 1,4-bis(cyanophenyldimethylsilyl)benzene (CPDMB), was synthesized and fully characterized by FT-IR, 1H NMR, 13C NMR, HRMS, and single crystal X-ray diffraction. Ultraviolet properties and steady-state fluorescence of CPDMB were studied. The concentration self-quenching phenomena of CPDMB were found in 2-propanol, THF, and CH2Cl2. It can be well interpreted by photoinduced self-assembly behavior (J-aggregate) of the CPDMB in solvents. Moreover, the effects of solvents on the fluorescence self-quenching phenomena were also investigated. In order to interpret the novel photoelectric properties of CPDMB, DFT calculations on gas phase CPDMB were carried out.
Co-reporter:Wen Yan Sun, Deng Xu Wang, Sheng Yu Feng
Chinese Chemical Letters 2009 Volume 20(Issue 3) pp:300-301
Publication Date(Web):March 2009
DOI:10.1016/j.cclet.2008.12.001
Carbosilane dendrimers with 4-bromo-N,N-dimethylaniline as end groups were synthesized from methyltrichlorosilane, allyl chloride, magnesium and 4-bromo-N,N-dimethylaniline. All compounds were characterized by 1H NMR, IR, MS.
Co-reporter:Wen Yan Sun, Hai Feng Lu, Deng Xu Wang, Sheng Yu Feng
Chinese Chemical Letters 2009 Volume 20(Issue 9) pp:1085-1087
Publication Date(Web):September 2009
DOI:10.1016/j.cclet.2009.05.016
A series of carbosilane dendrimers with acetyl end-group were synthesized. Their structures were characterized by 1H NMR, IR, and MS, respectively. Then dendrimers were coordinated with lanthanide ions (Eu3+ and Tb3+, respectively). The luminescence spectra of the complexes show narrow-width emissions in visible light region.
Co-reporter:Xuping Qin;Fang Zhao;Yingkai Liu;Hongyun Wang
Colloid and Polymer Science 2009 Volume 287( Issue 5) pp:621-625
Publication Date(Web):2009 May
DOI:10.1007/s00396-009-2018-z
HRM (hydrophilic reactive microgels) hydrogels based on acrylamide and 2-acrylamido-2-methylpropane sulfonic acid were prepared using HRM as a new crosslinking agent. HRM containing double bonds (C=C) were obtained by chemically modifying hydrophilic microgels (HM) of acrylamide with 2-acrylamido-2-methylpropane sulfonic acid. The resulting HRM hydrogels had high compression strength, elasticity, and elongation under high water content. The excellent mechanical performance is a main result of the unique microstructure of the hydrogels that are crosslinked by HRM instead of the conventional crosslinking agents such as N,N′–methylenebisacrylamide.
Co-reporter:Yunqiao Ding, Maoxia He, Yuzhong Niu, Dengxu Wang, Yan Cui and Shengyu Feng
The Journal of Physical Chemistry A 2009 Volume 113(Issue 38) pp:10291-10298
Publication Date(Web):August 27, 2009
DOI:10.1021/jp902920w
A density functional theory study for the bis- and monothiohene complexes of Fe, Co, and Ni (MT2 and MT, T = thiophene, M = Fe, Co, Ni) was performed to understand their coordination geometries, bonding properties, vibration spectra and singlet excited state spectra. The typical metal coordination exists in the complexes. The Fe−thiophene coordination has the highest stability, with Ni−thiophene being the second highest, and Co−thiophene the lowest. Bisthiophene complexes of Co and Ni prefer to homolytically dissociate to their monothiophene ones and free thiophene. Frequency calculation shows that the ligand−M−ligand asymmetric stretching vibration in bisthiophene complexes shows a strong absorption, at 435.2, 495.7, and 383 cm−1 for Fe(η4-T)2, Co(η2-T)2 and Ni(η2-T)2, respectively. The M−S stretching vibration in monothiophene complexes shows a strong absorption in the far-infrared region, at 209, 156, and 150 cm−1 for Fe(η4-T), Co(η4-T) and Ni(η5-T), respectively. The excited state spectra indicate that the characteristic absorption wavelengths of the complexes have a red shift of more than 12.40 eV compared to free thiophene, at 3.54, 1.64, 3.83, 2.75, 1.43, and 2.58 eV for Fe(η4-T)2, Co(η2-T)2, Ni(η2-T)2, Fe(η4-T), Co(η4-T), and Ni(η5-T), respectively.
Silicone/expanded graphite (EG) composites were prepared by melt mixing and solution intercalation. The effect of EG content and preparation methods of composites on thermal conductivity of composites were investigated, and it was found that with increasing EG, the thermal conductivity increased, and solution intercalation method showed better effect than melt mixing method in improving the thermal conductivity of composites. Dynamic mechanical analysis (DMA) was used to reveal that the storage modulus (E′) of SI-prepared composite is relatively greater than those of MM-prepared composite counterparts. The scanning electron microscopes (SEM) observation confirmed that striking increase of thermal conductivity might be attributable to higher surface-to-volume ratio of EG fillers.
Co-reporter:Xiaoli Zhu, Meng Zhang, Qingsi Zhang, Shengyu Feng, Xiang Z. Kong
European Polymer Journal 2005 Volume 41(Issue 9) pp:1993-2001
Publication Date(Web):September 2005
DOI:10.1016/j.eurpolymj.2005.03.004
With purpose to prepare waterborne polyurethane with improved performance, bis(methyoxyl hydroxyl)-functionalized polysiloxanes with different dimethylsiloxane segment length were prepared. The preparation includes three steps, the first is synthesis of 1,3-bis(glycidoxypropyl)tetramethyldisiloxane (compound I) via hydrosilylation of allylglycidyl ether with tetramethyldisiloxane, followed by a subsequent methoxylation of the resultant compound from the hydrosilylation to give 1,3-bis(3-(1-methoxy-2-hydroxypropoxy)propyl)tetramethyldisiloxane (compound II). Using this compound II and octamethylcyclotetrasiloxane (D4), an equilibrium reaction was carried out to obtain the target Product III, i.e. bis(methoxyl hydroxyl)-functionalized polysiloxanes. The ratio of D4/compound II was varied in order to prepare product III with different segment length consisting of dimethylsiloxane units. At each step, the outcome compounds were characterized through Infrared, 1H NMR, 13C NMR as well as H–H and H–C Correlated Spectroscopy (COSY). The results showed that each step was successfully carried out and objective products were achieved. It was estimated that compound II was not exclusive in the methoxylation step. Characterizations of the compound II enabled us to give a reliable quantitative amount for the by-products for the first time. In addition, the molecular weights of the final product III with varying dimethylsiloxane length were estimated by hydroxyl group analysis, 1H NMR and GPC, which showed a good agreement between the theoretical molecular weights and those from these tests.
Chemical Physics Letters 2005 Volume 415(4–6) pp:327-332
Publication Date(Web):11 November 2005
DOI:10.1016/j.cplett.2005.09.031
Abstract
The structures and isomerization of magnesium chlorosilylenoid H2SiClMgCl were investigated by ab initio molecular orbital theory for the first time. Four equilibrium structures and three isomeric transition states were located and fully optimized at the G3MP2B3 level. For more accurate structural analysis, the B3LYP/cc-pVTZ and QCISD/6-311+G* calculations were performed, respectively. Based on the B3LYP/6-31G(d) optimized geometries, 29Si chemical shifts and harmonic frequencies of various structures were obtained. Isomerization paths for isomers were confirmed by the intrinsic reaction coordinate (IRC) calculations. Tetrahedral, three-membered ring and p-complex structures are suggested to be experimentally detectable ones. σ-Complex structure has the highest energy and will not exist. The solvent effects were considered by means of the polarizable continuum model (PCM) using THF as a solvent.
European Polymer Journal 2004 Volume 40(Issue 1) pp:165-170
Publication Date(Web):January 2004
DOI:10.1016/j.eurpolymj.2003.09.013
A new polysiloxane with pendent sugar units was prepared by a two-step method: the preparation of the polysiloxane with amino groups on the side chain and then the copolysiloxane reacted with glucosyl isothiocyanate. All polymers were characterized by FT-IR 1H-NMR, 1H–1H-COSY, 13C-NMR, and DEPT respectively. In the same time, Platinum oxide was found to be a versatile and powerful hydrosilation catalyst in the hydrosilylation reaction of aminotrimethylenepolysiloxanes with heptamethylcyclotetrasiloxane (D4H).
European Polymer Journal 2003 Volume 39(Issue 8) pp:1623-1627
Publication Date(Web):August 2003
DOI:10.1016/S0014-3057(03)00039-9
Poly(methyltetraphenylphenylsilylene-co-1,4-bis(methylphenylsilyl)phenylene) (PSP) were synthesized by the cocondensation reaction of methyltetraphenylphenyldichlorosilane and 1,4-bis(chloromethylphenylsilyl)benzene with sodium in toluene. The optical and conducting properties of the polymer were investigated. Because of the introducing of tetraphenylphenyl groups to the Si atoms of the polymer, the ultraviolet (UV) absorption wavelengths of the PSP red-shift significantly in the UV region, and a strong photoluminescence band can be observed at visible region. Treatment of the films of PSP with I2 vapor afforded conducting films.
Co-reporter:Shengyu Feng, Dacheng Feng, Meijiang Li, Yuxiang Bu
Chemical Physics Letters 2001 Volume 339(1–2) pp:103-109
Publication Date(Web):4 May 2001
DOI:10.1016/S0009-2614(01)00327-X
The main characters of the potential energy surface of the methylenelithoflurosilylenoid (H2CSiLiF) are studied by ab initio calculations at the G2(MP2) level. Four equilibrium structures, a p-complex, a three-membered ring, a σ-complex and a silene, and three isomerization transition states are located, and isomerization reaction paths are investigated and confirmed by the intrinsic reaction coordinate (IRC) calculations. The calculations have shown that nonplanar p-complex structure has the lowest energy and should be experimentally detectable among four equilibrium structures of the H2CSiLiF. The silene and σ-complex structures have high energies and are easy to isomerize to the three-membered ring structure with lower energy, but in fact, they will not exist. Also, the structural characteristics and bonding properties of various structures are analyzed in this Letter.
Journal of Physics and Chemistry of Solids 2001 Volume 62(Issue 6) pp:1145-1148
Publication Date(Web):1 June 2001
DOI:10.1016/S0022-3697(01)00005-1
Based on trans-4-[P-(N-ethyl-N-hydroxylethyl-amino)styryl]-N-methylpyridinium tetraphenylborate (ASPT), three novel compounds of two ASPT-like charge transfer moieties linked by σ-bond spacers to N-position of pyridine cycle were synthesized. An interesting phenomenon has been found that by changing the number of the σ-bond spacers, the transition energy level can be micro-tuned, leading to an obvious shift of lasing λmax or up-conversion lasing λmax position under single-photon and two-photon pumped condition. An explanation of this phenomenon was proposed according to the quantum chemical calculation.
Journal of Physics and Chemistry of Solids 2001 Volume 62(Issue 6) pp:1075-1079
Publication Date(Web):1 June 2001
DOI:10.1016/S0022-3697(00)00283-3
Materials with large two-photon absorption (TPA) cross section are now gaining increasing attention since these can be exploited in a number of optical applications. In this paper, on the basis of a quantum–chemical INDO/CI method and by using the sum-over-states (SOS) expression, the theoretical predications on the TPA properties for a series of stilbene derivatives were performed. Some mechanism of effect on the TPA property is discussed and the results will provide theoretical basis for those dyes applied as TPA devices.
Co-reporter:Liying Fang, Jinglin Tan, Yan Zheng, Ge Yang, Jiangtao Yu, Shengyu Feng
Journal of Molecular Liquids (April 2017) Volume 231() pp:
Publication Date(Web):April 2017
DOI:10.1016/j.molliq.2017.02.017
•Two novel cationic silicone surfactants were synthesized successfully.•They have superior surface activity than conventional hydrocarbon surfactants.•They could self-assemble into spherical-like structures in aqueous solution.•They show good extraction ability for Au (III) and Pd (II).Two cationic silicone surfactants, 3-[tri-(trimethylsiloxy)]silylpropylpyridinium chloride (Si4pyrCl) and N-methyl-3-[tri-(trimethylsiloxy)]silylpropylpiperidinium chloride (Si4pipCl), were synthesized. Their aggregation behavior in aqueous solution was investigated through analyses of surface tension, electrical conductivity, dynamic light scattering (DLS), and transmission electron microscopy (TEM). Surface-tension measurements showed that the two cationic silicone surfactants decreased the surface tension of water to almost 20 mN m− 1. This result indicated the surfactants' remarkable surface activity. The effects of inorganic salts, sodium chloride, sodium bromide, sodium iodide and sodium sulfate, on the aggregation behavior of Si4pyrCl and Si4pipCl were systematically explored. Results showed that the aggregation of Si4pyrCl and Si4pipCl was promoted by the addition of salts and that aggregation ability followed the order of NaI > NaBr > Na2SO4 > NaCl. Thermodynamic parameters obtained from electrical-conductivity measurements indicated that the micellization of Si4pyrCl and Si4pipCl was entropy driven. Spherical aggregates with diameters ranging from 200 nm to 600 nm were observed by TEM, and the aggregates' diameter distribution was obtained by DLS. The extraction behavior on several metal ions (Co (II), Mn (II), Fe (III), Ni (II), Cu (II), Al (III), Sn (IV), Zn (II), Ce (III), Li (I), Mg (II), Au (III), and Pd (II)) in chloroform by the surfactants in chloroform was studied for the first time. Results showed that Si4pipCl and Si4pyrCl had good extraction ability for Au (III) and Pd (II).The aggregation behaviors of the two novel cationic silicone surfactants (Si4pyrCl and Si4pipCl) are investigated and it is greatly varied for the difference of the head groups. This Figure shows that the surface tension of water can be reduced almost to 20 mN m− 1, which indicates that both the two cationic silicone surfactants exhibit superior surface activity.
Co-reporter:Xuefeng Wang, Jiangyan Bian, Lichao Xu, Hua Wang and Shengyu Feng
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 48) pp:NaN32478-32478
Publication Date(Web):2015/11/16
DOI:10.1039/C5CP05473G
Two novel aggregation-induced emission enhancement (AIEE) molecules, namely, 3,4-diphenyl-2,5-di(2-thienyl)phenyltrimethylsilane (DPTB-TMS) and bis[3,4-diphenyl- 2,5-di(2-thienyl)phenyl]methylphenylsilane (DPTB-MPS) were designed and synthesized. The optical properties of the two silanes were completely opposite to the traditional luminescent materials. Unlike the aggregation caused quenching, they all emit faint fluorescence in the dispersed state, while emission intensity increased sharply in aggregate states. Fluorescence spectra showed that the two compounds exhibited AIEE properties and that is due to the weak π–π stacking caused by the restriction of intramolecular rotations of dye segments, particularly the –SiMe3 and thienyl groups in the aggregate state. As fluorescent (FL) probes, the fluorescence quenching behavior was further investigated. Thanks to the richer-electron thiophene groups, both compounds showed good performance in detecting nitroaromatics, especially picric acid (PA). The two AIEE FL probes exhibited better quenching efficiency in aqueous-based than in organic-based solutions. For DPTB-MPS, the addition of 80 μM nitrobenzene, 60 μM m-nitrobenzene and 40 μM PA resulted in about 50% quenching in aqueous solutions. The quenching mechanism would be electron transfer from silanes to nitroaromatics. This work provides a basis for designing organic-silanes with “abnormal” but useful optical properties and FL probes with AIEE properties for the detection of nitroaromatics.
Co-reporter:Dan Mu, Jian-Quan Li and Sheng-Yu Feng
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 19) pp:NaN12499-12499
Publication Date(Web):2015/04/07
DOI:10.1039/C5CP00561B
Twelve poly(ethylene oxide)-block-poly(methyl methacrylate) (PEO-b-PMMA) copolymers with lipid-like structures were designed and investigated by MesoDyn simulation. Spherical and worm-like micelles as well as bicontinuous, lamellar and defected lamellar phases were obtained. A special structure, designated B2412, with two lipid structures connected by their heads, was found to undergo four stages prior to forming a spherical micelle phase. Two possible assembly mechanisms were found via thermodynamic and dynamic process analyses; namely, the fusion and fission of micelles in dynamic equilibrium during the adjustment stage. Water can be encapsulated into these micelles, which can affect their size, particularly in low concentration aqueous solutions. The assignment of weak negative charges to the hydrophilic EO blocks resulted in a clear effect on micelle size. Surprisingly, the largest effect was observed with EO blocks with −0.5 e, wherein an ordered perfect hexagonal phase was formed. The obtained results can be applied in numerous fields of study, including adsorption, catalysis, controlled release and drug delivery.
Co-reporter:Hua Wang, Huanling Xie, Yan Liang, Linglong Feng, Xiyuan Cheng, Haifeng Lu and Shengyu Feng
Journal of Materials Chemistry A 2013 - vol. 1(Issue 34) pp:NaN5372-5372
Publication Date(Web):2013/07/10
DOI:10.1039/C3TC31097C
Well-defined organic composite nanoparticles were prepared from perylene bisimide dye and silicon-cored fluoranthene derivate molecules. The composite nanoparticles exhibited good stability and thermal properties. The fluorescence emission of the perylene bisimide dye can be efficiently enhanced in composite nanoparticles based on efficient Föster resonant energy transfer. The composite nanoparticles exhibited tunable emission colors from blue to red by changing the concentration of the perylene bisimide dye. White-light emission with CIE coordinates (0.327, 0.339) was obtained as a good candidate for applications in white optoelectronic devices.
Co-reporter:Huanling Xie, Hua Wang, Zhen Xu, Ruijing Qiao, Xuefeng Wang, Xianming Wang, Lianfeng Wu, Haifeng Lu and Shengyu Feng
Journal of Materials Chemistry A 2014 - vol. 2(Issue 44) pp:NaN9430-9430
Publication Date(Web):2014/09/17
DOI:10.1039/C4TC01183J
Two fluoranthene derivatives, nonsilicon-cored 7,10-diphenylfluoranthene (DF) and silicon-cored bis(7,10-diphenylfluoranthen-8-yl)diphenylsilane (BDS), were synthesized via the Knoevenagel/Diels–Alder method. The thermal properties and fluorescence quenching behavior of the derivatives with nitroaromatic compounds were investigated. Aside from its better thermal properties, BDS also showed lower detection limit, higher sensitivity, and higher quenching efficiency in detecting nitrobenzene and m-dinitrobenzene than DF. The detection limits of BDS were 50 and 10 ppm toward nitrobenzene and m-dinitrobenzene, respectively. Moreover, the Stern–Volmer plot of BDS swiftly curved upward, suggesting a super amplification effect. This result can be attributed to the special tetrahedral structure of BDS. Thus, BDS has great potential in the detection of explosives. This work may serve as a basis for designing new organic materials with great efficiency and sensitivity in fluorescence detection.
Co-reporter:Hua Wang, Yan Liang, Huanling Xie, Haifeng Lu, Shigui Zhao and Shengyu Feng
Journal of Materials Chemistry A 2016 - vol. 4(Issue 4) pp:NaN750-750
Publication Date(Web):2015/12/16
DOI:10.1039/C5TC03344F
In this paper, two new organic dyes derived from 1,8-naphthalimide and dendritic polyphenyl were designed and synthesized. Both the dyes exhibited unique aggregation-enhanced emission enhancement properties in methanol/water mixtures. The traditional fluorescent materials 1,8-naphthalimides were successfully transformed to AIE-active materials based on the dendritic polyphenyl structure. Furthermore, NPI-Ph and NPI-Si displayed excellent optical properties, such as solvent-induced emission changes from deep blue to light green, and the sensitive fluorescence response to nitroaromatic explosives. Interestingly, an unexpected SiMe3 effect was found in the two dyes: the SiMe3-containing compound NPI-Si exhibited remarkably enhanced optical properties compared with the non-SiMe3 compound NPI-Ph such as a wider color-tunable range and higher sensitivity for the fluorescence detection of nitroaromatic explosives. The dendritic polyphenyl strategy and the SiMe3 effect reported in this work will provide guidance to the design of AIE-active molecules and fluorescent materials for detecting nitroaromatic explosives.
Preparation of POSS–min–DS, an octaimidazolium-based polyhedral oligomeric silsesquioxanes (POSS) room temperature ionic liquid, by an ion-exchange reaction between POSS and sodium dodecyl sulfate was reported. Octaimidazolium-based POSS was synthesized with more than 98% yield within 3 h. POSS–min–DS and octaimidazolium-based POSS were confirmed by 1H, 13C, and 29Si NMR, FT-IR and elemental analysis.
Pseudopolyrotaxanes (POSS/CB[7]) were synthesized using octaimidazolium-based polyhedral oligomeric silsesquioxanes (POSS) and cucurbit[7]uril (CB[7]) in aqueous solution. The binding interactions were monitored by 1H NMR. Their regular octahedral morphologies were confirmed by TEM. The POSS/CB[7] was also characterized by FT-IR, thermogravimetric analysis (TGA), and elemental analysis. The TGA results show that the thermal stabilities of POSS/CB[7] can be improved by the threading of CB[7].
Co-reporter:Dengxu Wang, Wenyan Yang, Liguo Li, Xian Zhao, Shengyu Feng and Hongzhi Liu
Journal of Materials Chemistry A 2013 - vol. 1(Issue 43) pp:NaN13558-13558
Publication Date(Web):2013/09/04
DOI:10.1039/C3TA12324C
Cubic octavinylsilsesquioxane successively reacts with different tetrahedral silicon-centered precursors containing di-, tri-, or tetrabromophenyl groups to prepare hybrid porous polymers (HPPs) via Heck reaction. The resulting materials possess high porosities with Brunauer–Emmett–Teller specific surface areas of up to 875 m2 g−1. Their porosities can be tuned by altering the number of the connecting sites of silicon-centered units. For gas storage applications, HPP-5 exhibits the following properties: a high H2 uptake of 7.76 mmol g−1 (1.56 wt%) at 77 K and 1.01 bar; a moderate CO2 uptake of 1.04 mmol g−1 (4.58 wt%) at 298 K and 1.04 bar; and a low CH4 uptake of 0.28 mmol g−1 (0.45 wt%) at 298 K and 1 bar. These results suggest that these polymers can be applied as promising materials for H2 and CO2 storage as well as the selective adsorbents of CO2 rather than CH4. These polymers are also luminescent with the maximum emission at ca. 420 nm in the solid state; therefore, they could be potentially applied as blue light-emitting materials.
Co-reporter:Hua Wang, Yan Liang, Huanling Xie, Linglong Feng, Haifeng Lu and Shengyu Feng
Journal of Materials Chemistry A 2014 - vol. 2(Issue 28) pp:NaN5606-5606
Publication Date(Web):2014/05/21
DOI:10.1039/C4TC00570H
In this paper, we report the synthesis and optical behavior of tetraphenyl benzene and its two derivatives. All the three compounds exhibited aggregation-enhanced emission (AEE) properties at a low concentration. The AEE mechanism was investigated and is due to restricted intramolecular rotation and unique packing structure. Furthermore, this kind of dendritic benzene derivatives exhibited interesting optical properties with increased concentration. Furthermore, we found a new phenomenon that the silicon-cored structure could efficiently enhance emission intensity and adjust the emission colors of dendritic benzene. The phenomenon was called “silicon-cored effect.” This effect may give some guidance to the design of new luminescent materials with AIE and AEE properties.
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 40) pp:NaN26789-26789
Publication Date(Web):2015/09/09
DOI:10.1039/C5CP03658E
Poly(amidoamine) dendrimers are typical luminescent polymers containing unconventional chromophores. A series of novel siloxane–poly(amidoamine) (Si–PAMAM) dendrimers were synthesized and investigated in this study. Their structures and properties were determined by NMR, XPS, LC/MS, and fluorescence spectroscopy. The introduction of Si–O–Si units in Si–PAMAM changed the photophysical properties of the dendrimers. The luminescence of Si–PAMAM was associated with the aggregation of its carbonyl groups, which was caused by N → Si coordination bonds. The strong blue luminescence of Si–PAMAM was also studied in detail, and it was found to be quite different from the ethanediamine-based poly(amidoamine). Results indicated that the luminescence of Si–PAMAM could be controlled by solvents, acids, metal ions, temperature, or degree of aggregation of the carbonyl groups. Moreover, micron-sized tubes composed of Si–PAMAM molecules were generated and found in water/methanol solution.
Co-reporter:Yujing Zuo, Haifeng Lu, Lei Xue, Xianming Wang, Liang Ning and Shengyu Feng
Journal of Materials Chemistry A 2014 - vol. 2(Issue 15) pp:NaN2734-2734
Publication Date(Web):2014/01/28
DOI:10.1039/C3TC32382J
Novel transparent and luminescent silicone elastomers were prepared by thiol–ene chemistry. They show very intense photoluminescence under ultraviolet light and have very high coloric purity. The luminescence was obtained by complexing lanthanide ions into an N-acetyl–L–cysteine functionalized polysiloxane. The functionalized polysiloxane was prepared by an easy thiol–ene reaction and the polysiloxane was cured by thiol–ene reaction to get a crosslinking network. Their structures and properties were characterized thoroughly. The experimental results indicate complexing lanthanide ions reduced the contact angles.
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