Co-reporter:Aizhao Pan, Matthew J. Jurow, Fen Qiu, Juan Yang, Baoyi Ren, Jeffrey J. Urban, Ling He, and Yi Liu
Nano Letters November 8, 2017 Volume 17(Issue 11) pp:6759-6759
Publication Date(Web):October 2, 2017
DOI:10.1021/acs.nanolett.7b02959
Despite the exceptional optoelectronic characteristics of the emergent perovskite nanocrystals, the ionic nature greatly limits their stability, and thus restricts their potential applications. Here we have adapted a self-assembly strategy to access a rarely reported nanorod suprastructure that provide excellent encapsulation of perovskite nanocrystals by polymer-grafted graphene oxide layers. Polyacrylic acid-grafted graphene oxide (GO-g-PAA) was used as a surface ligand during the synthesis of the CsPbX3 perovskite nanocrystals (NCs), yielding particles (5–12 nm) with tunable halide compositions that were homogeneously embedded in the GO-g-PAA matrix. The resulting NC-GO-g-PAA exhibits a higher photoluminescence quantum yield than previously reported encapsulated NCs while maintaining an easily tunable bandgap, allowing for emission spanning the visible spectrum. The NC-GO-g-PAA hybrid further self-assembles into well-defined nanorods upon solvent treatment. The resulting nanorod morphology imparts extraordinary chemical stability toward protic solvents such as methanol and water and much enhanced thermal stability. The introduction of barrier layers by embedding the perovskite NCs in the GO-g-PAA matrix, together with its unique assembly into nanorods, provides a novel strategy to afford robust perovskite emissive materials with environmental stability that may meet or exceed the requirement for optoelectronic applications.Keywords: Hybrid materials; nanorod; perovskite nanocrystals; photoluminescence; self-assembly;
Co-reporter:Hu Pingan;Jia Mengjun;Zuo Yanyan;He Ling
RSC Advances (2011-Present) 2017 vol. 7(Issue 5) pp:2450-2459
Publication Date(Web):2017/01/04
DOI:10.1039/C6RA25579E
A cross-linked silica and polyvinyl alcohol (PVA) hybrid material was prepared via a sol–gel process for use as a highly transparent, thermostable and mechanically strong coating. The effect of the H2O/TEOS ratio on the properties of the silica/PVA hybrid films, such as transmittance, thermal stability, mechanical strength, adhesive strength and hygrothermal resistance, is discussed herein. A strong chemical interaction between PVA and silica is indicated by the weakening of the C–OH peak and the formation of a Si–O–C peak in the XPS results. This interaction is further confirmed by the decrease in the PVA crystallinity from 23.29% to 2.56%, and the reduction in the silica/PVA melting point from 204.3 °C to 122.0 °C. This excellent compatibility between PVA and silica makes silica/PVA disperse well in solution with a dendritic-like or spherical morphology, and leads to a 97% increase in visible light transmittance. Therefore, compared with pure PVA, the obtained silica/PVA hybrid films are transparent. Even though the mass percentage of silica in the material is beyond 50 wt%, its Young's modulus is much improved from 0.17 ± 0.03 GPa to 2.52 ± 0.10 GPa, its ultimate tensile strength is enhanced from 40.1 ± 9.27 MPa to 80.3 ± 2.5 MPa, and its adhesive strength is increased from 475 N (1.52 MPa) to 712 ± 90 N (2.29 MPa) and it can almost maintain super hygrothermal resistance after 15 hygrothermal aging cycles. It is believed that the obtained silica/PVA hybrid could be used as a high-performance coating with excellent transparency, thermostability and mechanical strength.
Co-reporter:Shahid Sultan;Khalida Kareem;Stefan Simon
Analytical Methods (2009-Present) 2017 vol. 9(Issue 5) pp:814-825
Publication Date(Web):2017/02/02
DOI:10.1039/C6AY03157A
In order to identify the authenticity and to find the difference of pigments used in the south and north parts of China, on ancient Chinese artworks, painted samples were collected from different ancient grottos, tombs and architecture from the Tang dynasty (AD 618–907) and the Ming dynasty (1368–1644) and these were evaluated by comparison with pure pigments mostly used in ancient artworks. A total of 23 ancient green, red, blue, black and white pigmented samples were collected from the Guangyuan Thousand Buddha Grotto (AD 618–907), Da Yun Cave (AD 618–907), Emperor Li Shimin Tomb (AD 599–649) and Bell Tower (AD 1368–1644) and were analyzed using X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscope with energy dispersive X-ray spectroscopy. Furthermore, each sample was analyzed for the presence of the 24 main elements using inductively coupled plasma emission spectrometry to understand the main contribution of the elements to the color, especially in the mixtured pigments. Among the 23 ancient painted samples, the main red pigments are miniumite (2PbO·PbO2), hematite (Fe2O3) and cinnabar (HgS), white pigments are anglesite (PbSO4), zinc white (ZnO) and gypsum (CaSO4·2H2O), green pigments are malachite (CuCO3·Cu(OH)2) and atacamite (CuCl2·3Cu(OH)2), and blue pigments are cobalt blue (CoO·Al2O3), chrysocolla ((Cu,Al)2H2Si2O5(OH)4·nH2O) and lazurite (Na3Ca(Si3Al3)O12S). In many cases, the painted colors are made of a mixture of pigments. It was revealed that six samples of GB-W (white), BT-W (white), GB-B (blue), DY-BLK (black), GB-G2 (green) and LS-BLK (black) were not in their original or pure form, and so they might have been repainted in the recent past, and possibly been retouched with modern colors. It is believed that the proposed analytical approach provides a bright future for the identification of original and fake painted artwork.
Co-reporter:Yanli Ma, Ling He, Mengjun Jia, Lingru Zhao, Yanyan Zuo, Pingan Hu
Journal of Colloid and Interface Science 2017 Volume 500(Volume 500) pp:
Publication Date(Web):15 August 2017
DOI:10.1016/j.jcis.2017.04.029
Three polysiloxane/epoxy hybrids obtained by evolving cage- or linear-structured polysiloxane into poly glycidyl methacrylate (PGMA) matrix are compared used as coatings. One is the cage-structured hybrid of P(GMA/MA-POSS) copolymer obtained by GMA and methacrylisobutyl polyhedral oligomeric silsesquioxane (MA-POSS) via free radical polymerization, the other two are PGMA/NH2-POSS and PGMA/NH2-PDMS hybrids by cage-structured aminopropyllsobutyl POSS (NH2-POSS) or linear-structured diamino terminated poly(dimethylsiloxane) (NH2-PDMS) to cure PGMA. The effect of MA-POSS, NH2-POSS and NH2-PDMS on polysiloxane/epoxy hybrid films is characterized according to their surface morphology, transparency, permeability, adhesive strength and thermo-mechanical properties. Due to caged POSS tending to agglomerate onto the film surface, P(GMA/MA-POSS) and PGMA/NH2-POSS films exhibit much more heterogeneous surfaces than PGMA/NH2-PDMS film, but the well-compatibility between epoxy matrix and MA-POSS has provided P(GMA/MA-POSS) film with much higher transmittance (98%) than PGMA/NH2-POSS film (24%), PGMA/NH2-PDMS film (27%) and traditional epoxy resin film (5%). The introduction of polysiloxane into epoxy matrix is confirmed to create hybrids with strong adhesive strength (526–1113 N) and high thermos-stability (Tg = 262–282 °C), especially the cage-structured P(GMA/MA-POSS) hybrid (1113 N and 282 °C), but the flexible PDMS improves PGMA/NH2-PDMS hybrid with much higher storage modulus (519 MPa) than PGMA/NH2-POSS (271 MPa), which suggests that PDMS is advantage in improving the film stiffness than POSS cages. However, cage-structured P(GMA/MA-POSS) and PGMA/NH2-POSS indicate higher permeability than PGMA/NH2-PDMS and traditional epoxy resin. Comparatively, the cage-structured P(GMA/MA-POSS) hybrid is the best coating in transparency, permeability, adhesive strength and thermostability, but linear-structured PGMA/NH2-PDMS hybrid behaviors the best coating in mechanical property.Download high-res image (230KB)Download full-size image
Co-reporter:Yanli Ma, Ling He
Materials Chemistry and Physics 2017 Volume 201(Volume 201) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.matchemphys.2017.08.017
•POSS-pendanted epoxy hybrid of PGMA-g-P(MA-POSS) is prepared.•The highly thermo-mechnical property and significant water resistance of film are obtained.•Super thermal endurance, humidity resistance and permeability of films are approved.•A great potential application of PGMA-g-P(MA-POSS) as coatings is expected.Organic-inorganic hybrid is prepared by grafting nano-scaled methacrylisobutyl polyhedral oligomeric silsesquioxane (MA-POSS) onto glycidyl methacrylate (GMA) via the combining of free radical polymerization, epoxy opening reaction and atom transfer radical polymerization (ATRP) techniques. The obtained (MA-POSS)-pendanted epoxy hybrid, PGMA-g-P(MA-POSS), are discussed fot their highly thermo-mechnical property, hydrothermal resistance and permeability based on the self-assembled micelles. In THF solution, PGMA-g-P(MA-POSS) could self-assembly into 110–800 nm sphereric core-shell micelles, while, the pre-curing PGMA-g-P(MA-POSS) distributes 60–600 nm core-shell micelles because the developed three-dimensional network structure makes the PGMA chains twining and cross-linking tightly leading to the shrinkage of particles. These self-assembled micelles have provided the casted films with 0.19–14.4 nm surface roughness, significant water resistance (SCA = 113-123°), high thermal stability (Td = 300–600 °C) and strong adhesive strength (216–333 N). Compared with the poor adhesive strength for commercial epoxy resin (E-51) decreased from 393 N to 28 N after 15 hydrothermal cycles, the obtained PGMA-g-P(MA-POSS) displays super thermal endurance properties and humidity resistance by keeping a relative constant adhesive strength (from 340 N to 337 N). Furthermore, PGMA-g-P(MA-POSS) also gives much better permeability to the protective treated sandstone than E-51. Therefore, PGMA-g-P(MA-POSS) is prospected to serve as coatings with great potential applications.Download high-res image (118KB)Download full-size image
Co-reporter:Aizhao Pan;Matthew Jurow;Yanrui Zhao;Fen Qiu;Ya Liu;Juan Yang;Jeffrey J. Urban;Yi Liu
Nanoscale (2009-Present) 2017 vol. 9(Issue 45) pp:17688-17693
Publication Date(Web):2017/11/23
DOI:10.1039/C7NR06579E
Ordered self-assembled arrays or superstructures of nanocrystals (NCs) have attracted intense research interest due to their ability to translate valuable nanoscale properties to larger length scales. Numerous techniques have been explored to induce self-assembly into various superstructures. Here we investigated a simple kinetic approach to form self-assembled one-dimensional perovskite CsPbX3 (X: halides) nanocrystal arrays templated inside a pod shaped inert lead sulfate (PbSO4) scaffold. Both the solvent effects, and the self-assembly process and mechanism, are systematically studied based on a uniform procedure developed to generate CsPbX3 nanocrystal superlattices with different sizes and compositions. The formation of one-dimensional (1D) chains of NCs within a half-cylindrical pod of PbSO4 reflects a balance between solvophobicity and solvophilicity of the components. By reducing the size of NCs, we successfully realized 2D superlattices with two or three rows of close-packed CsPbBr3 NCs, in addition to single string-of-pearl type 1D assemblies. The superlattices can be assembled both inside and outside of the half-cylindrical shells by regulating the reaction conditions. The self-assembly behavior is reminiscent of the host–guest systems of organic molecular species where supramolecular recognition rules apply to give well-defined complexes. The current study opens a door for controlling self-assembled nanostructures of CsPbX3 NCs, and provides an attainable platform for future optoelectronic devices.
Co-reporter:Hong Guo
Colloid and Polymer Science 2017 Volume 295( Issue 5) pp:827-836
Publication Date(Web):2017 May
DOI:10.1007/s00396-017-4065-1
Amphiphilic fluorocopolymer P (PEGMA)-co-P (DFHM) is prepared by hydrophobic dodecafluorohrptyl methacrylate (DFHM) and hydrophilic poly (ethylene glycol) methyl ether methacrylate (PEGMA) monomers via atom transfer radical polymerization (ATRP). The self-assembled colloids of P (PEGMA)-co-P (DFHM) in ethanol, dimethylformamide (DMF), tetrahydrofuran (THF), and chloroform (CHCl3) solutions are discussed according to solvent dielectric constants (ε = 38.3–4.8). The hydrophilic/hydrophobic property, protein resistance, and adhesive strength of films formed by these colloids are evaluated based on the surface morphologies and chemical compositions. P (PEGMA)-co-P (DFHM) can self-assembly into core-shell micelles composed of P (PEGMA) shell and P (DFHM) core (~130 nm) as 500–600 nm in DMF, 300–400 nm in ethanol, and 200–250 nm in THF and CHCl3 solutions. These colloids provide the film surfaces with high fluorine content (39.40–41.70 wt%) to indicate the migration of fluorine-containing groups onto the film surface during the film formation and therefore the obvious hydrophilic/hydrophobic properties (94.3°–102.4° water contact angles and 58.5°–60.2° cetane contact angles). Comparatively, DMF-casted film gains the highest surface roughness (Ra = 0.98 nm), the lowest fluorine content (39.40 wt%), and the highest surface free energy (20.41 mN m−1) due to its large size of colloids, but CHCl3-casted film gives the lowest surface free energy (17.82 mN m−1). The adhesive strength for DMF- and ethanol-casted films (210 and 168 N) proves higher than THF- and CHCl3-casted films (105 and 63 N), while DMF-casted film shows much better protein resistance (Δf = −15.0 Hz) than other three films (Δf = −17–20 Hz). It is believed that the obtained P (P EGMA)-co-P(DFHM) could have a promising application as solvent-dependent and protein-resistance coatings.
Co-reporter:Khalida Kareem, Shahid Sultan, Ling He
Materials Chemistry and Physics 2016 Volume 169() pp:158-172
Publication Date(Web):1 February 2016
DOI:10.1016/j.matchemphys.2015.11.044
•Chemical formed patina on Cu–Sn–Pb bronze are characterized.•Surface morphologies of cracks, pits and corrosion depth of multicolor patina are revealed.•Different corrosion behavior and deterioration rate by aggressive environments are discussed.•Schematic sketch/model to elaborate corrosion phenomenon is investigated.This paper presents the chemical corrosion behavior and surface morphologies including cracks, pits and corrosive-depth of “patina” in the different metallographic Cu–Sn–Pb bronze alloys by the trace amounts of S2−, SO42−, NO3−, Cl− and CO32− aggressive environments. Typical patinas have been formed as brochantite patina (Cu4SO4·(OH)6) by SO42− solution with 46–144 μm corrosion depth, atacamite patina (Cu2(OH)3Cl) by Cl− solution through many subsequent “dissolution-ion pairing-precipitation” steps with 15–70 μm corrosion depth, gerhardite patina (Cu(NO3) (OH)3) by NO3- solution with 0.3 μm corroded layer, gerhardite or lead nitrate (Pb(NO3)2) or malachite (Cu2(OH)2CO3) patina by CO32−/NO3- solution as 390 μm depth of corrosive layer, atacamite Cu2Cl(OH)3 along with cuprite (Cu2O) and cessiterite (SnO2) patina with 11–390 μm multilayered corrosive crust by CO32−/Cl− solution, and a mixed black patina of brochantite, brendtite (SnS2), roxbyite (Cu7S4) by S2− solution with 34–256 μm corrosive depth. Among all environments, the deterioration rate is evaluated as order of S2− > CO32−/Cl− > Cl− > CO32−/NO3- > SO42− > NO3−. The minor bronze disease is observed in highly tin-contained alloys (>19%), while the amount of lead in alloy exhibits no specific role in corrosion. Based on these results, the phenomenological models of corrosion behavior due to an internal oxidation, ionic migration and de-alloying of “a protective barrier” are proposed.
Co-reporter:Junyan Liang, Li Wang, Jingxian Bao, Ling He
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2016 Volume 507() pp:26-35
Publication Date(Web):20 October 2016
DOI:10.1016/j.colsurfa.2016.07.056
•Three types of alkenyl-functionalized SiO2 particles (AFSPs) were prepared.•SiO2-g-PS particles were prepared via grafting of AFSPs with PS chains.•The dispersion of SiO2-g-PS particles relied on the morphological structure of AFSPs.•Casting SiO2-g-PS/fluoroalkylsilane composite yielded a super-repellent coating.Alkenyl-functionalized SiO2 particles (AFSPs) were prepared, grafted and co-cast with fluoroalkylsilane to produce superhydrophobic and highly oleophobic coatings. In preparation of AFSPs, vinyltrimethoxysilane (VTMS) and γ-methacryloxypropyltrimethoxysilane (MPTMS) were employed separately to react with SiO2 nanoparticles (NPs) through the ex situ neutral condensation. In contrast, the reaction of MPTMS with SiO2 NPs was also executed through the in situ alkali-catalyzed sol-gel technique. It showed that the obtained neutral condensed VTMS-SiO2 and MPTMS-SiO2 NPs had a surface with a thin grafted layer of VTMS and MPTMS, respectively, whereas the alkali-catalyzed MPTMS-SiO2 NPs had a surface bearing a slightly thicker MPTMS hydrolysate-condensate layer. Polystyrene (PS) was allowed to graft onto the AFSPs to prepare SiO2-g-PS particles via emulsion polymerization of styrene (St) from each of these three AFSPs. The uniform SiO2-g-PS particles were obtained exclusively by the growth of PS from neutral condensed MPTMS-SiO2 NPs. SiO2-g-PS/fluoroalkylsilane composites for coating were subsequently prepared by the in situ hydrolysis of 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (FDTES) in the suspension of uniform SiO2-g-PS particles. It was found that the use of smaller SiO2-g-PS particles and high-content FDTES contributed to the creation of a coating that exhibited superhydrophobicity with low adhesion and high oleophobicity with high adhesion.
Co-reporter:Aizhao Pan, Ling He, Liang Wang, Na Xi
Materials Today: Proceedings 2016 Volume 3(Issue 2) pp:325-334
Publication Date(Web):2016
DOI:10.1016/j.matpr.2016.01.077
Linear/star-shaped polyhedral oligomeric silsesquioxane (POSS)-based fluorinated diblock copolymers are synthesized by octakis(dibromoethyl)-POSS (POSS-(Br)16) and aminopropylisobutyl-POSS (ap-POSS) initiating methylmethacrylate (MMA) and dodecafluoroheptylmethacrylate (DFHM), respectively. The effect of solvents on their self-assembled micelles, surface wetability and viscoelasticity of casted films, and the hydrophobic application are characterized. In THF, CHCl3 and dimethyl carbonate (DMC) solutions, the self-assembled micelles of star-shaped s-POSS-(PMMA-b-PDFHM)16 are larger than linear-shaped ap-POSS-PMMA-b-PDFHM. CHCl3-casted surface gains the highest roughness, fluoride content, water contact angles, but the lowest water adsorption and viscoelasticity. CHCl3-micelles exhibit superhydrophobicity to stone and cotton fiber substrates. Therefore, POSS-based fluoropolymer is hoped to act as hydrophobic coatings.
Co-reporter:Hongpu Huang;Jia Qu
Journal of Polymer Science Part A: Polymer Chemistry 2016 Volume 54( Issue 3) pp:381-393
Publication Date(Web):
DOI:10.1002/pola.27785
ABSTRACT
A series of amphiphilic silica/fluoropolymer nanoparticles of SiO2-g-P(PEGMA)-b-P(12FMA) were prepared by silica surface-initiating atom transfer radical polymerization (SI-ATRP) of poly(ethylene glycol) methyl ether methacrylate (PEGMA) and poly dodecafluoroheptyl methacrylate (P12FMA). Their amphiphilic behavior, lower critical solution temperature (LCST), and surface properties as protein-resistance coatings were characterized. The introduction of hydrophobic P(12FMA) block leads SiO2-g-P(PEGMA)-b-P(12FMA) to form individual spherical nanoparticles (∼150 nm in water and ∼170 nm in THF solution) as P(PEGMA)-b-P(12FMA) shell grafted on SiO2 core (∼130 nm), to gain obvious lower LCST at 36–52 °C and higher thermostability at 290–320 °C than SiO2-g-P(PEGMA) (LCST = 78–90 °C, Td = 220 °C). The water-casted SiO2-g-P(PEGMA)-b-P(12FMA) films obtain much rougher surface (125.3–178.4 nm) than THF-casted films (11.5–16.9 nm) and all SiO2-g-P(PEGMA) films (26.8–31.3 nm). Therefore, the water-casted surfaces exhibit obvious higher water adsorption amount (Δf = −494 ∼ −426 Hz) and harder adsorbed layer (viscoelasticity of ΔD/Δf = −0.28 ∼ −0.36 × 10−6/Hz) than SiO2-g-P(PEGMA) films, but present loser adsorbed layer than THF-casted films (ΔD/Δf = −0.29 ∼ −0.63 × 10−6/Hz). While, the introduction of P(12FMA) segments does not show obviously reduce in the protein-repelling adsorption of SiO2-g-P(PEGMA)-b-P(12FMA) films (△f = −15.7 ∼ −22.3 Hz) compared with SiO2-g-P(PEGMA) films (△f = −8.3 ∼ −11.3 Hz) and no obvious influence on water adsorption of ancient stone. Therefore, SiO2-g-P(PEGMA)-b-P(12FMA) is suggested to be used as protein-resistance coatings. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016, 54, 381–393
Co-reporter:Aizhao Pan, Bo He, Xiaoyun Fan, Zeke Liu, Jeffrey J. Urban, A. Paul Alivisatos, Ling He, and Yi Liu
ACS Nano 2016 Volume 10(Issue 8) pp:7943
Publication Date(Web):August 1, 2016
DOI:10.1021/acsnano.6b03863
While convenient solution-based procedures have been realized for the synthesis of colloidal perovskite nanocrystals, the impact of surfactant ligands on the shape, size, and surface properties still remains poorly understood, which calls for a more detailed structure–morphology study. Herein we have systematically varied the hydrocarbon chain composition of carboxylic acids and amines to investigate the surface chemistry and the independent impact of acid and amine on the size and shape of perovskite nanocrystals. Solution phase studies on purified nanocrystal samples by 1H NMR and IR spectroscopies have confirmed the presence of both carboxylate and alkylammonium ligands on surfaces, with the alkylammonium ligand being much more mobile and susceptible to detachment from the nanocrystal surfaces during polar solvent washes. Moreover, the chain length variation of carboxylic acids and amines, ranging from 18 carbons down to two carbons, has shown independent correlation to the size and shape of nanocrystals in addition to the temperature effect. We have additionally demonstrated that employing a more soluble cesium acetate precursor in place of the universally used Cs2CO3 results in enhanced processability without sacrificing optical properties, thus offering a more versatile recipe for perovskite nanocrystal synthesis that allows the use of organic acids and amines bearing chains shorter than eight carbon atoms. Overall our studies have shed light on the influence of ligand chemistry on crystal growth and stabilization of the nanocrystals, which opens the door to functionalizable perovskite nanocrsytals through surface ligand manipulation.Keywords: colloidal nanocrystal; nanocubes; nanoplatelets; perovskite; surface chemistry
Co-reporter:Liang Junyan, Wang Li, Bao Jingxian and He Ling
Journal of Materials Chemistry A 2015 vol. 3(Issue 40) pp:20134-20144
Publication Date(Web):27 Jul 2015
DOI:10.1039/C5TA04428F
Herein, we focus on the creation of durable superhydrophobic and highly oleophobic coating through the casting of multi-dome hydrophobic SiO2 nanoparticles (NPs) modified with fluoroalkylsilane onto a glass plate, followed by coating the surface of pre-stacked particles with another layer of poly(methyl methacrylate)-b-poly(dodecafluoroheptyl methacrylate; PMMA-b-PDFHM). The novel multi-dome hydrophobic SiO2 NPs had re-entrant surfaces covered by methacryloxy groups, which were facilely prepared via a reaction of pristine SiO2 NPs with γ-methacryloxypropyltrimethoxysilane (MPTMS) using an in situ alkali-catalyzed sol–gel process in an n-propanol (NPA) solution. Fluoroalkylsilane-modified SiO2 NPs were prepared by the in situ hydrolysis of 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (FDTES) in a THF–H2C2O4 (aq.) suspension of multi-dome hydrophobic SiO2 NPs. It was found that a decrease in the content of hydrolyzed–condensed FDTES contributed to the reduction in conglutination and the aggregation of multi-dome hydrophobic SiO2 NPs in the obtained coating layer, leading to a relatively loose surface structure with gaps or cavities. In this case, the coating surface supported the Cassie–Wenzel transition state with hexadecane and thus exhibited high oleophobicity with high adhesion. Moreover, superhydrophobicity with water droplets adopting a low-adhesive bouncing Cassie mode was achieved. More importantly, the coating was still well adhered to the glass substrate and demonstrated high oleophobicity and superhydrophobicity after it was subjected to scouring tests using strong base and acid aqueous solutions.
Co-reporter:Na Wang, Ling He, Xiang Zhao, Stefan Simon
Microchemical Journal 2015 Volume 123() pp:201-210
Publication Date(Web):November 2015
DOI:10.1016/j.microc.2015.06.007
•Eastern tung-oil and western drying-oil are distinguished by on-line methylated Py–GC/MS.•Mono/di-carboxylic acids and other hydrolyzed products are identified in all drying-oils.•Benzene derivative and 9,10-dihydroxy-octadecanoic acid are used to distinguish drying-oil.•Cinnabar could significantly accelerate the aging and hydrolyzing rate of drying-oil.•The established procedure is successfully applied on the identifying real painting samples.The mostly used drying-oils as binding media in historical artworks of eastern tung-oil and western linseed-oil, poppy-oil, walnut-oil are comparatively identified by on-line methylated pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS). Based on the analysis of un-pigmented and pigmented reference samples after treated by natural aging, hydro-thermal aging and UV aging, respectively, the characteristic pyrolysis products of all drying-oils are classed into mono-carboxylic acids (C6–8, 14, 16, 18, 20), di-carboxylic acids (2C6–12), glycerol, erythritol, 2-tridecanone, 8-hydroxy-octanoic acid, 3-octyl-oxiraneoctanoic acid and 2,6,10-trimethyl-9-undecenoic acid. Both benzene derivative and 9,10-dihydroxy-octadecanoic acid are suggested as the marked components for distinguishing eastern and western drying-oil. The investigated pigments of malachite, cinnabar, azurite and ochre do not show obvious influence on the detection of characteristic pyrolysis products of drying-oil, but they are proved to accelerate the aging and hydrolyzing rate of drying-oil, especially the pigment of cinnabar. The established on-line methylated Py–GC/MS procedure and the summarized data have been successfully applied on the identification of raw tung-oil and boiled tung-oil in historical painting samples collected from Drum Tower (Ming Dynasty), Bell Tower (Ming Dynasty), and Thousand-Buddha Cliff Grotto (Tang Dynasty). It is believed that the established Py–GC/MS procedure is able to provide wide application in archeological research.
Co-reporter:Shao Yang, Aizhao Pan, Ling He
Materials Chemistry and Physics 2015 Volume 153() pp:396-404
Publication Date(Web):1 March 2015
DOI:10.1016/j.matchemphys.2015.01.032
•The novel hybrids of PDMS-b-PMMA408-b-P(MA-POSS) 4.5, 8.2, 13.6 are synthesized for coating.•Thermostability and storage modulus of hybrids are enhanced.•The surface of film casting from CHCl3 obtains superior hydrophobicity than film from THF.•P(MA-POSS)-rich surface could store absorbed water without increase viscoelasticity of film.Novel organic/inorganic hybrids of PDMS-b-PMMAm-b-P(MA-POSS)n are synthesized by linear poly(dimethylsiloxane) (PDMS) macroinitiator initiating methyl methacrylate (MMA) and caged methacrylisobutyl-polyhedral oligomeric silsesquioxane (MA-POSS) via a two-step ATRP technique. The chemical structures of obtained hybrids are proved to be PDMS-b-PMMA408-b-P(MA-POSS)4.5, 8.2, 13.6 with molecular weight of 50,090–58,650 g mol−1 (PDI = 1.215–1.391). With the increase of P(MA-POSS)n content from 0%wt to 23.93%wt, the glass transition temperature of PDMS-b-PMMA408-b-P(MA-POSS)n is enhanced from 95 °C to 137 °C, and the corresponding storage modulus of mechanical property is increased from 579 ± 3 MPa to 902 ± 5 MPa. The surface of PDMS-b-PMMA408-b-P(MA-POSS)8.2 film casting from CHCl3 solution obtains higher water contact angle (120°) and higher water adsorption (Δf = −2300 Hz), but lower viscoelasticity (ΔD = 26 × 10−6) than the film casting from tetrahydrofuran (THF) solution (114°, Δf = −1540 Hz, ΔD = 52 × 10−6). This is because that 200–500 nm core/shell micelles of PMMA core and PDMS/P(MA-POSS) shell formed in CHCl3 solution are favor of the migration of PDMS and P(MA-POSS) onto film surface to improve the surface roughness (2.480 nm) and to get silicon-rich surface (14.62%) than 220 nm P(MA-POSS) core/PMMA shell/PDMS-corona micelles formed in THF solution (0.906 nm, 7.86%). Therefore, the accumulated P(MA-POSS) cages on the film surface are able to store absorbed water but do not increase the viscoelasticity of film. The results indicate that PDMS-b-PMMA408-b-P(MA-POSS)n are promising to be the solvent-dependent coating materials.
Co-reporter:Jia Qu;Jing Liu
Journal of Applied Polymer Science 2015 Volume 132( Issue 11) pp:
Publication Date(Web):
DOI:10.1002/app.41650
ABSTRACT
Starch is sensitive to moisture and is weak to durability in the protection application to ancient relics. Therefore, two fluorosilicone-modified starches are firstly prepared and evaluated for the protection of historic stones. The fluoro-silicone copolymer grafted starch of P(VTMS/12FMA)-g-starch is synthesized by grafting copolymer of vinyltrimethoxysilane (VTMS) and dodecafluoroheptyl methacrylate (12FMA) onto starch. While the fluoro-silicone starch latex of VTMS-starch@P(MMA/BA/3FMA) is obtained by emulsion polymerization of VTMS primarily grafted-starch (VTMS-starch) with methyl methacrylate (MMA), butyl acrylate (BA) and 2,2,2-trifluoroethyl methacrylate (3FMA). The grafting fluorosilicone copolymer onto starch improves obviously their hydrophobic and thermal properties. Comparatively, VTMS-starch@P(MMA/BA/3FMA) film performs higher water contact angle (107°) and thermal stability (350–430°C) than p(VTMS/12FMA)-g-starch film (72°, 250–420°C) due to the migration of fluorine-containing group onto the surface of film during the film formation. Therefore, VTMS-starch@P(MMA/BA/3FMA) shows much better protective performance in water-resistance, and salt/freeze-thaw resistance for stone samples. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41650.
Co-reporter:Yanli Ma;Aizhao Pan;Chengben Zhao
Journal of Materials Science 2015 Volume 50( Issue 5) pp:2158-2166
Publication Date(Web):2015 March
DOI:10.1007/s10853-014-8778-y
The novel latex of P(GMA-POSS)-co-PMMA is synthesized for coatings by glycidyl methacrylate polyhedral oligomeric silsesquioxane (GMA-POSS) and methyl methacrylate (MMA). First, GMA-POSS is prepared by the epoxide opening reaction of glycidyl methacrylate (GMA) and aminopropyllsobutyl POSS (NH2-POSS). Then, the as-obtained GMA-POSS monomer is directly used for emulsion polymerization with MMA to obtain P(GMA-POSS)-co-PMMA latex. The chemical structure of P(GMA-POSS)-co-PMMA latex is characterized. The core–shell morphology of latex is proved to distribute uniform spherical particles as 20–60 nm in diameter. The effect of POSS content on the properties of film casting from P(GMA-POSS)-co-PMMA latex is studied for surface roughness, static contact angle, thermostability, and universal mechanical testing. The introducing of POSS into latex leads to an increase of P(GMA-POSS)-co-PMMA in the hydrophobicity, adhesive strength, thermal and mechanical proprieties. When GMA-POSS amount is controlled at 33 wt%, the glass transition temperature (Tg) and static contact angle are increased into 130 °C and 102º, respectively, and the adhesion to the substrate is raised to 477.2 MPa. Therefore, P(GMA-POSS)-co-PMMA is promising to be suggested as coating material.
Co-reporter:Aizhao Pan;Tao Zhang;Xiang Zhao
Colloid and Polymer Science 2015 Volume 293( Issue 8) pp:2281-2290
Publication Date(Web):2015 August
DOI:10.1007/s00396-015-3618-4
The novel fluorine/silicon-containing triblock copolymers PFMAm-b-PMMAn-b-PMPSp are synthesized by poly(2,2,3,3,4,4,4,-hexafluorobutyl methacrylate)-Cl initiating methylmethacrylate (MMA) and 3-(trimethoxysilyl)propyl methacrylate (MPS). Their self-assembled micelles and the film surface are studied. The typical core-shell (CS) micelles self-assembled in tetrahydrofuran (THF), chloroform (CHCl3), and butanone (MEK) are proved to have PFMA-core/poly(3-(trimethyoxysilyl)propyl methacrylate) PMPS/poly methylmethacrylate (PMMA)-shell structure, but have different morphlogy as 200-nm spherical CS, 190-nm half-spherical layered CS, and 340-nm multicore CS in THF, CHCl3, and MEK, respectively. The results reveal that the migration of PFMA segments onto the film surface is strongly controlled by the micelle structures. Therefore, the film surface casted from micelles obtains low wettability (θa = 105–120° and θr = 102°–119°) and viscoelasticity (ΔD/Δf = −0.03 to −0.31×10−6 Hz−1). The lowest water adsorption and viscoelastic surface is created by the spherical CS in THF, but the film casted from MEK and CHCl3 behave rather flexible surfaces. PFMAm-b-PMMAn-b-PMPSp gains high thermal stability (375 °C) and strong adhesion strength (≥54 N).
Co-reporter:Hongpu Huang and Ling He
RSC Advances 2014 vol. 4(Issue 25) pp:13108-13118
Publication Date(Web):24 Jan 2014
DOI:10.1039/C3RA47393G
Silica/diblock fluoropolymer hybrids SiO2-g-PMMA-b-P12FMA for coatings were synthesized by the silica surface-initiating atom transfer radical polymerization (SI-ATRP) of methylmethacrylate (MMA) and dodecafluoroheptyl methacrylate (12FMA). Silica surface initiator (SiO2-initiator) was obtained by 10–25 nm fumed silica particles grafted hydrosilylated undec-10-enyl, 2-bromo-2-methyl propionate with a density of 0.573 mmol g−1. The SI-ATRP approach in this paper displays the diagnostic criteria of controlled radical polymerization by the analysis of 1H NMR, 19F NMR and SEC-MALLS analysis, after comparing with the conventional initiator of ethyl 2-bromoisobutyrate (EBiB) for the E-PMMA-b-P12FMA diblock copolymer. Three mass ratios of SiO2-initiator/MMA/12FMA as 1/72.50/18.15, 1/72.50/45.38 and 1/181.26/18.15 were used to obtain the SiO2-g-PMMA-b-12FMA hybrids. The hybrids show 25–30 nm core–shell particles in CHCl3 solution composed of a P12FMA core and PMMA shell, but densely twined together as agglomerated particles. The PMMA-b-P12FMA shell grafted onto silica particles obviously increases the surface roughness of the film (50–500 nm), more than the E-PMMA-b-12FMA film (30 nm), and thereby contributes to the hydrophobic (112–118°) and oleophobic (45–78°) properties of the films. Increasing the P12FMA concentration (1/72.50/45.38) could result in stronger migration of the P12FMA segments onto the film surface, and therefore led to a lower surface free energy (10.97 mN m−1), increased advancing and receding for water contact angles (112° and 108°) and the highest cetane contact angles (74° and 70°), the lower water absorption and viscoelasticity, but a high thermostability at 420–450 °C.
Co-reporter:Na Wang, Ling He, Ellen Egel, Stefan Simon, Bo Rong
Microchemical Journal 2014 Volume 114() pp:125-140
Publication Date(Web):May 2014
DOI:10.1016/j.microc.2013.12.011
•The sequence of the gilded and pigmented layers and their composition are described.•Three kinds of ancient Chinese gilding techniques are identified for the first time.•Copper foil, crocoite and modern red pigment are identified in one “gilded” sample.•The painting layers are mostly atacamite, cinnabar, minium, yellow ochre and gypsum.•Mixture of cinnabar and minium is used in the red sample.The gilding and painting techniques for the clay-based polychromic sculptures in Jizo Hall of Chongqing Temple, Shanxi Province of China, are analyzed by complementary techniques of microscopy, environmental scanning electron microscopy (ESEM), energy dispersive X-ray mapping (EDX), micro-Raman spectroscopy (μ-RS), and Fourier transform infrared spectroscopy (FTIR) with a reasonable sequence. 7 gilded samples and 6 pigmented samples are collected from Jizo Hall. For the 7 gilded polychromic samples, drying oil-based, Chinese lacquer-based and glue-based “Jin Jiao” techniques are identified respectively according to their different adhesive layers used for jointing gold leaf to the preparation layer. But the presence of a copper foil top surface, as well as the inner layers with crocoites (PbCrO4) and modern red pigment in one alleged gilded polychromic sample indicate a later restoration work. Among them, two gold layers have been identified in 4 samples due to the regilded work in history. For 6 pigmented samples, painting layer is generally applied on a white preparation layer made of kaolinite or the mixture of kaolinite and gypsum. Atacamite, cinnabar, minium, yellow ochre and gypsum are identified as the main pigments, and the protein-based material is confirmed as the binding medium for red pigments. This research not only reveals the Chinese traditional gilding and painting techniques employed in polychromic sculptures of Jizo Hall, but also demonstrates the advantages and limitations of each analytical technique for identifying polychromic samples, and the necessity of complementary analytical techniques approach.
Co-reporter:Mingjun Niu, Ling He, Junyan Liang, Aizhao Pan, Xiang Zhao
Progress in Organic Coatings 2014 Volume 77(Issue 11) pp:1603-1612
Publication Date(Web):November 2014
DOI:10.1016/j.porgcoat.2014.05.008
•The fluorosilicone pentablock copolymers are synthesized by ATRP.•The effect of different fluorinated side chains on the surface properties of films is discussed.•The effect of solvents on the self-assembly and film surface is investigated.•The high content of unimers contributes much to the lower surface energy of film.•The high content of micelles helps to form rough surface of film.The linear fluorosilicone pentablock copolymers PDMS-b-(PMMA-b-PFMA)2 are synthesized via two-step ATRP approaches by dimethylsiloxane (DMS), methyl methacrylate (MMA) and fluorinated methacrylate (FMA). Trifluoroethyl methacrylate (3FMA), hexafluorobutyl methacrylate (6FMA), octafluoropentyl methacrylate (8FMA) and dodecafluoroheptyl methacrylate (12FMA) are used as FMA. The effect of different fluorinated side chains on the surface properties of PDMS-b-(PMMA-b-PFMA)2 films indicates that 3FMA, 6FMA and 8FMA behave the similar surface properties as lower water contact angles (θ(H2O) = 105–106°) and higher surface free energy (26.83–27.55 mN/m) than P12FMA (θ(H2O) = 116°, 19.52 mN/m) due to the competing migration between the PFMA and PDMS chains. Therefore, the effect of chloroform (CHCl3), tetrahydrofuran (THF), trifluorotoluene (TFT) and CHCl3–TFT solvents on the self-assembly and surface properties of PDMS-b-(PMMA-b-P12FMA)2 film is investigated by DLS, TEM, SCA, XPS, SEM, AFM and QCM-D. A typical bimodal distribution with high content of micelles (310 nm, 93%) in CHCl3 solution and high content of unimers (17 nm, 70%) in CHCl3–TFT solution are formed, but a special unimodal distribution of unimers (15 nm) in THF solution and micelles (75 nm) in TFT solution are found. The micelles are confirmed by TEM as P12FMA core–PDMS/PMMA shell in CHCl3 solution, but PDMS core–PMMA/P12FMA shell in TFT and CHCl3–TFT solutions. The results reveal that the higher content of unimers contributes much to the fluorine-rich surface, higher cetane contact angle, lower surface energy and lower viscoelasticity for the film, but the higher content of micelles promote forming the roughness surface. Therefore, the most hydrophobic surfaces are the films casting from THF and CHCl3–TFT solution.
Co-reporter:Aizhao Pan, Shao Yang, Ling He and Xiang Zhao
RSC Advances 2014 vol. 4(Issue 53) pp:27857-27866
Publication Date(Web):04 Jun 2014
DOI:10.1039/C4RA03337J
Novel 16-arm, star-shaped POSS-containing diblock copolymers are first synthesized by methylmethacrylate (MMA) and methacrylisobutyl polyhedral oligomeric silsesquioxane (MA-POSS) using a cetylfunctional initiator of octakis(dibromoethyl) POSS (POSS-(Br)16). Three well-defined copolymers of s-POSS-PMMA277.3-b-P(MA-POSS)5.8,16.4,25.4 are discussed. The introduction of P(MA-POSS) could provide the copolymer with excellent hydrophobic/oleophobic performance and thermal stability. Although the size of core–shell micelles of s-POSS-PMMA277.3-b-P(MA-POSS)5.8–25.4 does not increase linearly with increasing MA-POSS content due to different self-assembly behaviors and steric effects, surface roughness (0.44–1.41 nm) and water–hexadecane contact angles (108°/50°–120°/58°) of films, as well as thermal stability (Td = 350–380 °C, Tg = 112–125 °C) and storage modulus (842–1600 MPa) of copolymers increased linearly. The effect of solvents on self-assembled micelles and films indicates that 340–370 nm core–shell micelles, 330–370 nm sun-like stretching micelles and 180–200 nm three-layer-structured micelles are formed in tetrahydrofuran (THF), chloroform (CHCl3) and butanone (MEK) solution, respectively. The lowest surface free energy (17.48 m Nm−1) is produced by film casting from THF solution due to the highest surface roughness (1.12 nm) and Si content (6.01%). While, the lowest water absorptive (Δm = 3800 ng cm−2) and viscoelastic (ΔD/Δf = −0.36) film is produced by CHCl3 solution, the film casting from MEK solution exhibits the highest water absorption (Δm = 6500 ng cm−2) and viscoelasticity (ΔD/Δf = −0.15). This is the first example of a 16-arm, star-shaped POSS diblock copolymers, and can be used as solvent-dependent coatings.
Co-reporter:Aizhao Pan, Ling He
Materials Chemistry and Physics 2014 Volume 147(1–2) pp:5-10
Publication Date(Web):15 September 2014
DOI:10.1016/j.matchemphys.2014.04.027
•Two novel hybrids PDMM@SiO2 and SiO2@PDMM are obtained.•Effect of core–shell structure on the properties of hybrids and film is investigated.•PDMM@SiO2 film provides obvious hydrophobicity, high Tg and storage modulus.Two novel core–shell pentablock copolymer/silica hybrids are prepared for coating applications via growing silica on the precursor of pentablock copolymer PDMS-b-(PMMA-b-PMPS)2 (PDMM), which is synthesized by dimethylsiloxane (DMS), methylmethacrylate (MMA) and 3-(trimethyoxysilyl)propyl methacrylate (MPS). The hybrid of PDMM core/silica shell (PDMM@SiO2) is obtained by the assembled PDMM in THF/CH3OH solution with tetraethyl orthosilicate (TEOS), but the hybrid of silica core/PDMM shell (SiO2@PDMM) is obtained by the hydrolyzed TEOS with –Si(OCH3)3 groups during assembling of PDMM in THF solution. PDMM@SiO2 could produce a film distributed agminated SiO2 particles with 45 nm roughness, but SiO2@PDMM could produce a film scatted individual SiO2 particles with 26 nm roughness. Therefore, PDMM@SiO2 film gives an obvious hydrophobicity (116°), higher Tg (121 °C), high Td (>400 °C), low amount of water absorption (300 Hz of Δf), low viscoelasticity (−0.32 of ΔD/Δf), but tight layer structure (10 × 10−6 of ΔD) and high storage modulus (2350 MPa). However, both core–shell hybrids have the similar adhesion to the substrate (185–187 N).Two novel core–shell pentablock copolymer/silica hybrids are prepared for coating applications, PDMM core/silica shell (PDMM@SiO2) and silica core/PDMM shell (SiO2@PDMM), by pentablock copolymer and 20% TEOS. The effect of different core–shell structure on the film hydrophobicity, water absorption, viscoelasticity, Tg, storage modulus and adhesion to the substrate is discussed.
Co-reporter:Gang Chang, Ling He, Junyan Liang, Na Wang, Ruijun Cao, Xiang Zhao
Journal of Fluorine Chemistry 2014 Volume 158() pp:21-28
Publication Date(Web):February 2014
DOI:10.1016/j.jfluchem.2013.11.015
Highlight•Present a new strategy for fluorosilicone copolymers core–shell latexes.•The effect of 6FA, 3FMA, 6FMA and 12FMA monomers on the latex is investigated.•The longer side chains of 12FMA contribute much to the lower surface free energy.•P(D4/D4V)/p(BA/MMA/12FMA) latex gives a lower wettability and water absorption film.The core–shell polysiloxane/fluoroacrylate copolymer latexes p(D4/D4V)/p(BA/MMA/FA) are prepared for coating materials. P(D4/D4V) core is synthesized by ring-opening polymerization of octamethylcyclotetrasiloxane (Si4O4(CH3)8, D4) and tetravinyltetramethylcyclotetrasiloxane (Si4O4(CH3)4(C2H3)4, D4V). P(BA/MMA/FA) shell is obtained by semi-continuous seed emulsion copolymerization of methyl methylacrylate (MMA), butyl acrylate (BA) and fluorinated acrylate (FA) via. Four different FA are used in this paper: hexafluorobutyl acrylate (6FA), trifluoroethyl methacrylate (3FMA), hexafluorobutyl methacrylate (6FMA) and dodecafluoroheptyl methacrylate (12FMA). The as-prepared latexes are characterized by Fourier transforms infrared (FT-IR) spectroscopy and 1H NMR measurement. The typical core–shell structure is proved by transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The effect of different shells on the core–shell particles and the surface properties of films are characterized by TEM, dynamic light scattering (DLS), scanning electron microscope coupled with the energy dispersive spectrometry (SEM-EDX), static contact angles (SCA) for surface free energy, and quartz crystal microbalance with dissipation (QCM-D) monitoring for surface water absorption. With the increase of fluoridated side chain in the shell, the individual core–shell particles as 70–90 nm are obtained. The surface free energy for p(D4/D4V)/p(BA/MMA/12FMA) film (19 mN/m) is much lower than other three films (28–29 mN/m). During the film formation, the self-aggregation of CF3 groups onto the film surface for lower surface free energy and the polysiloxane groups onto the substrate for better adhesion. Therefore, p(D4/D4V)/p(BA/MMA/12FMA) film is much more homogeneous, less wettability and less water absorption.
Co-reporter:Aizhao Pan;Shao Yang ;Mingjun Niu
Journal of Applied Polymer Science 2014 Volume 131( Issue 9) pp:
Publication Date(Web):
DOI:10.1002/app.40209
Abstract
The reactive rate and surface wettability of three pentablock copolymers PDMS-b-(PMMA-b-PR)2 (R = 3FMA, 12FMA, and MPS) obtained via ATRP for coatings are discussed. Poly(dimethylsiloxane) (PDMS) is used as difunctional macroinitiator, poly(methyl methacrylate) (PMMA) as the middle block, while poly(trifluoroethyl methacrylate) (P3FMA), poly(dodecafluoroheptyl methacrylate) (P12FMA) and poly(3-(trimethoxysilyl)propyl methacrylate) (PMPS) as the end block, respectively. Their reactive rates obtained by gas chromatography (GC) analysis indicate that 3FMA gains 8.053 × 10−5 s−1 reactive rate and 75% conversion, higher than 12FMA (4.417 × 10−5 s−1, 35%), but MPS has 1.9389 × 10−4 s−1 reactive rate and 96% conversion. The wettability of pentablock copolymer films is characterized by water contact angles (WCA) and hexadecane contact angles (HCA). The PDMS-b-(PMMA-b-P12FMA)2 film behaves much higher advancing and receding WAC (120° and 116°) and HCA (60° and 56°) than PDMS-b-(PMMA-b-P3FMA)2 film (110° and 106° for WAC, 38° and 32° for HAC) because of its fluorine-rich surface (20.9 wt % F). However, PDMS-b-(PMMA-b-PMPS)2 film obtains 8° hysteretic contact angle in WAC (114°–106°) and HAC (32°–24°) due to its higher surface roughness (138 nm). Therefore, the fluorine-rich and higher roughness surface could produce the lower water and oil wettability, but silicon-rich surface will produce lower water wettability. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40209.
Co-reporter:Junyan Liang, Li Wang, Ling He and Shaodong Sun
Physical Chemistry Chemical Physics 2013 vol. 15(Issue 26) pp:10921-10929
Publication Date(Web):02 May 2013
DOI:10.1039/C3CP00044C
Two poly(4-vinylpyridine)-b-polystyrene diblock copolymer/silica core–shell nanoparticles (P4VP-b-PS/SiO2 NPs) are developed in this work. Confirmed by DLS analysis and TEM observation, one comprises a SiO2 core surrounded by a P4VP-b-PS shell and the other comprises a P4VP-b-PS core surrounded by a SiO2 shell, which is facilely prepared by the in situ hydrolysis of tetraethyl orthosilicate (TEOS) using cationic P4VP-b-PS micelles obtained in a THF–H2C2O4 (aq, 0.1 mol L−1) mixture and a DMF–H2C2O4 (aq, 0.01 mol L−1) mixture as template, respectively. The SCA, CAH, SA and SEM measurements reveal that one-step deposition of P4VP-b-PS/SiO2 NPs with SiO2 cores formed at a high level of TEOS creates a superhydrophobic surface with an SCA of 160°, a CAH of 2° and an SA of around 4° originating from the formation of a typical micro–nanoscale binary structure (MNBS). For the NPs with SiO2 cores formed at a low level of TEOS, the superhydrophobicity with a SCA of 151°, CAH of 3° and SA of around 5° can be induced by the transition of the surface microstructure from an uneven and discontinuous MNBS, created by a one-step deposition process, to the coexistence of MNBS and a nanoscale structure (NS) after annealing with toluene for 30 min. In contrast, one-step deposition of P4VP-b-PS/SiO2 NPs with P4VP-b-PS cores and SiO2 shells usually results in the inhomogeneous precipitation of SiO2 from bulk P4VP-b-PS along with the production of micro-cracks, with which is impossible to achieve surface superhydrophobicity.
Co-reporter:Xia Dong, Ling He, Na Wang, Jun-Yan Liang, Ming-Jun Niu and Xiang Zhao
Journal of Materials Chemistry A 2012 vol. 22(Issue 43) pp:23078-23090
Publication Date(Web):13 Sep 2012
DOI:10.1039/C2JM35400D
Diblock fluoroacrylate copolymers poly(methyl methacrylate) (PMMA)-b-poly(dodecafluoroheptyl methacrylate) (PMMA-b-PDFHM) for coating materials are synthesized via atom transfer radical polymerization (ATRP) by two different initiators, a brominated initiator end group terminated by 1H,1H,2H,2H-heptadecafluoro (F–Br) and the conventional initiator ethyl 2-bromoisobutyrate (EBiB). The copolymer structures are characterized by 1H NMR, 19F NMR and GPC analyses. The influence of the two initiators on the self-assembly behavior and the surface properties of PMMA-b-PDFHM films are explored. Because of the divergent solubility of the segments in chloroform (CHCl3), tetrahydrofuran (THF) and trifluorotoluene (TFT) solutions, the self-assembly of PMMA-b-PDFHM in CHCl3, THF and TFT was investigated using dynamic light scattering (DLS) and transmission electron microscopy (TEM). Accordingly, the properties of PMMA-b-PDFHM films cast from CHCl3, THF and TFT solutions were compared for their surface wettability, surface free energy, surface elemental composition, surface morphology and roughness, and surface water adsorption, through analysis of static contact angle (SCA), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and quartz crystal microbalance with dissipation (QCM-D). It is found that the copolymers F-PMMA-b-PDFHM using F–Br initiator and E-PMMA-b-PDFHM using EBIB initiator, reveal both unimers (7–9 nm) and micelles (220–360 nm) in THF and CHCl3 solutions, which are recognized by TEM as dichroic half-spherical or core–shell particles, but occur mainly as unimers (5–9 nm) in TFT solution, which is favorable for obtaining films with low surface free energies. F-PMMA-b-PDFHM films show lower surface free energy (17.1–17.7 mN m−1) than E-PMMA-b-PDFHM films (17.9–22.9 mN m−1) in each solvent. The surface morphology and roughness determined are strongly controlled by the cast solutions. F-PMMA-b-PDFHM films exhibit a low wettability and high stable surface due to a well-ordered fluorocarbon surface provided by both PDFHM and F–Br groups, and therefore can be developed into a high-performance coating material.
Co-reporter:Junyan Liang, Ling He, Xia Dong, Tie Zhou
Journal of Colloid and Interface Science 2012 Volume 369(Issue 1) pp:435-441
Publication Date(Web):1 March 2012
DOI:10.1016/j.jcis.2011.12.028
The surfaces of films cast from core–shell fluorosilicone acrylate copolymer (BA/MMA/DFHM and BA/MMA/DFHM/MPTMS/D4) latexes and linear pentablock fluorosilicone acrylate copolymer (PDMS-b-(PMMA-b-PDFHM)2) solutions are intensively investigated and compared by XPS, DCA, AFM, and QCM-D measurements. It is found that the molecular structures and in-solution aggregate structures of these well-defined copolymers have a dramatic influence on the surface structure formation, surface wetting, and adsorption behavior. The PDMS-b-(PMMA-b-PDFHM)2 film cast from chloroform solution with high concentration of low-density unimers is able to perform as strong surface self-segregation of fluorine-containing groups as core–shell copolymer latex films. The BA/MMA/DFHM/MPTMS/D4 in the core–shell latex particles exhibits the less pronounced surface self-segregation of silicon-containing groups than PDMS-b-(PMMA-b-PDFHM)2 due to the occurrence of cross-linking reactions between polysiloxane chains. Indeed, such reactions induce the formation of silica network within the film material, which immobilizes tightly the fluorinated groups on the film surface and thus endows the film with higher surface structural stability for water compared to PDMS-b-(PMMA-b-PDFHM)2 film with similar surface fluorine concentration and even higher silicon concentration. Still, the PDMS-b-(PMMA-b-PDFHM)2 film definitely demonstrates higher advancing and receding contact angles for water than BA/MMA/DFHM/MPTMS/D4 latex film in the case of synergism between surface enrichment of fluorine and silicon.Graphical abstractHighlights► PDMS-b-(PMMA-b-PDFHM)2 in chloroform has strong surface migration of F and Si atoms. ► Surface oleophobicity of films is highly sensitive to the presence of Si enrichment. ► QCM-D technique is carried out to investigate the surface adsorption behavior of film. ► Cross-linked BA/MMA/DFHM/MPTMS/D4 shows high surface structural stability for water.
Co-reporter:Ling He, Na Wang, Xiang Zhao, Tie Zhou, Yin Xia, Junyan Liang, Bo Rong
Journal of Archaeological Science 2012 Volume 39(Issue 6) pp:1809-1820
Publication Date(Web):June 2012
DOI:10.1016/j.jas.2012.01.022
This paper presents a multi-analytical study of the polychromy in the Guangyuan Thousand-Buddha Grotto. Samples taken from 15 locations in No. 512 and No. 689 caves are prepared as cross-sections for the analysis by optical microscopy (OM) and scanning electron microscopy coupled with backscattered electron imaging (SEM-BSE). The cross section analysis indicates that some paintings were repainted in the past. The chemical composition of each painting layer is obtained by scanning electron microscopy coupled with energy-dispersive X-ray analysis (SEM-EDX). The main pigments for 15 samples including green, red, blue, white and black paint layers, are identified by the combination of polarized light microscopy (PLM), Fourier Transform infrared spectrum (FT-IR), Raman spectroscopy (RS) and X-ray diffraction (XRD) analysis. The integrated analytical results reveal that the green pigments are malachite and atacamite; the red color is attributed to minium, hematite and cinnabar; the blue pigments are lazurite and organic blue materials; the white color is ascribed to anglesite and gypsum; and the black surface of polychrome is the accumulation of longtime smudging by folk burning incense in the devotional practice or the soot deposition resulting from burning bonfires in the caves. Some arsenic-containing pigment is detected in the green samples. This case study also demonstrates the advantages and the limitations of every analytical technique for the pigment identification, confirming the necessity of the integrated analytical techniques approach. The present results are not only useful to assist in the authenticity of the used pigment materials and history of the polychromic in the past, but also aimed at guiding the conservation scientists in taking into account materials and methods utilized in the past.Graphical abstractHighlights► A multi-analytical study of the polychromy in ancient Chinese Grotto is presented. ► The polychromic structures are recognized as the monolayer or multilayer in 15 samples. ► The main pigments are identified as green, red, blue and white materials. ► Arsenic-containing pigment is detected in the green samples. ► The most completed color-stratigraphy is characterized as five color sections.
Co-reporter:Zheng Wei;He Ling;Liang Junyan;Chang Gang ;Wang Na
Journal of Applied Polymer Science 2011 Volume 120( Issue 2) pp:1152-1161
Publication Date(Web):
DOI:10.1002/app.33000
Abstract
A core–shell nanosilica (nano-SiO2)/fluorinated acrylic copolymer latex, where nano-SiO2 served as the core and a copolymer of butyl acrylate, methyl methacrylate, and 2,2,2-trifluoroethyl methacrylate (TFEMA) served as the shell, was synthesized in this study by seed emulsion polymerization. The compatibility between the core and shell was enhanced by the introduction of vinyl trimethoxysilane on the surface of nano-SiO2. The morphology and particle size of the nano-SiO2/poly(methyl methacrylate–butyl acrylate–2,2,2-trifluoroethyl methacrylate) [P(MMA–BA–TFEMA)] core–shell latex were characterized by transmission electron microscopy. The properties and surface energy of films formed by the nano-SiO2/P(MMA–BA–TFEMA) latex were analyzed by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy/energy-dispersive X-ray spectroscopy, and static contact angle measurement. The analyzed results indicate that the nano-SiO2/P(MMA–BA–TFEMA) latex presented uniform spherical core–shell particles about 45 nm in diameter. Favorable characteristics in the latex film and the lowest surface energy were obtained with 30 wt % TFEMA; this was due to the optimal migration of fluorine to the surface during film formation. The mechanical properties of the films were significantly improved by 1.0–1.5 wt % modified nano-SiO2. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Co-reporter:Liang Junyan;He Ling;Li Weidong;Luo Hongjie
Polymer International 2009 Volume 58( Issue 11) pp:1283-1290
Publication Date(Web):
DOI:10.1002/pi.2660
Abstract
BACKGROUND: Silicon-containing fluoroacrylate copolymers are potential materials for use in the protection of ancient stone buildings. In the work reported in this paper, a new core–shell silicon-containing fluoroacrylate latex was prepared through grafting of a fluoroacrylate copolymer latex with polysiloxane.
RESULTS: The core–shell silicon-containing fluoroacrylate latex was successfully synthesized by seed emulsion polymerization and octamethylcyclotetrasiloxane (D4) ring-opening polymerization in the presence of a mixed emulsifier consisting of a non-ionic emulsifier and a novel fluorine-containing anionic emulsifier sodium perfluoro-octane sulfonate. Transmission electron microscopy, X-ray photoelectron spectroscopy, static contact angle measurements and scanning electron microscopy-energy dispersive X-ray analysis showed that when the D4 content was controlled at 2.84–4.36 wt%, the silicon-containing fluoroacrylate latex presented a uniform sphere core-shell structure and had strong hydrophobic and oleophobic characters due to the association of both fluorine and silicon atoms on the latex film surface. The film cross-section exhibited uniform and dense microstructure without any phase segregation. Additionally, thermogravimetric analysis and tensile test results indicated that all the silicon-containing fluoroacrylate copolymers displayed better thermal stability and higher flexibility.
CONCLUSION: The synthetic core–shell silicon-containing fluoroacrylate latex showed excellent surface properties, thermal stability and flexibility, and has encouraging prospects in application as a protective coating. Copyright © 2009 Society of Chemical Industry
Co-reporter:Liang Junyan;He Ling;Zheng Yuansuo
Journal of Applied Polymer Science 2009 Volume 112( Issue 3) pp:1615-1621
Publication Date(Web):
DOI:10.1002/app.29577
Abstract
Three core-shell fluoroacrylate copolymer latices with different fluorinated side chain structure were synthesized in this article by semicontinuous seed emulsion polymerization, using butyl acrylate (BA) and methyl methacrylate (MMA) as acrylate monomer and trifluoroethyl methacrylate (TFEM, C6H7O2F3), hexafluorobutyl methacrylate (HFBM, C8H8O2F6), and dodecafluoroheptyl methacrylate (DFHM, C11H8O2F12) as fluorine-containing acrylate monomer. The core-shell fluoroacrylate copolymer latices were named as BA/MMA/TFEM, BA/MMA/HFBM, and BA/MMA/DFHM, respectively. The latex particle morphology and the particle size were determined by transmission electron microscopy and differential scanning calorimetry. The final chemical structure of the latex was analyzed by NMR. The effect of the fluorinated side chain on the core-shell copolymer latex and film properties, as well as on the superiority of core-shell copolymer latex to general fluoroacrylate copolymer latex was investigated by energy dispersive X-ray detector, thermogravimetric analysis, and the determination of contact angle. The analysis results indicated that the particle of fluoroacrylate copolymer latex presented uniform sphere core-shell structure. Compared with core-shell BA/MMA/TFEM and BA/MMA/HFBM, BA/MMA/DFHM exhibited not only better surface property as increasing temperature but also better thermal stability. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Co-reporter:Xia Dong, Ling He, Na Wang, Jun-Yan Liang, Ming-Jun Niu and Xiang Zhao
Journal of Materials Chemistry A 2012 - vol. 22(Issue 43) pp:NaN23090-23090
Publication Date(Web):2012/09/13
DOI:10.1039/C2JM35400D
Diblock fluoroacrylate copolymers poly(methyl methacrylate) (PMMA)-b-poly(dodecafluoroheptyl methacrylate) (PMMA-b-PDFHM) for coating materials are synthesized via atom transfer radical polymerization (ATRP) by two different initiators, a brominated initiator end group terminated by 1H,1H,2H,2H-heptadecafluoro (F–Br) and the conventional initiator ethyl 2-bromoisobutyrate (EBiB). The copolymer structures are characterized by 1H NMR, 19F NMR and GPC analyses. The influence of the two initiators on the self-assembly behavior and the surface properties of PMMA-b-PDFHM films are explored. Because of the divergent solubility of the segments in chloroform (CHCl3), tetrahydrofuran (THF) and trifluorotoluene (TFT) solutions, the self-assembly of PMMA-b-PDFHM in CHCl3, THF and TFT was investigated using dynamic light scattering (DLS) and transmission electron microscopy (TEM). Accordingly, the properties of PMMA-b-PDFHM films cast from CHCl3, THF and TFT solutions were compared for their surface wettability, surface free energy, surface elemental composition, surface morphology and roughness, and surface water adsorption, through analysis of static contact angle (SCA), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and quartz crystal microbalance with dissipation (QCM-D). It is found that the copolymers F-PMMA-b-PDFHM using F–Br initiator and E-PMMA-b-PDFHM using EBIB initiator, reveal both unimers (7–9 nm) and micelles (220–360 nm) in THF and CHCl3 solutions, which are recognized by TEM as dichroic half-spherical or core–shell particles, but occur mainly as unimers (5–9 nm) in TFT solution, which is favorable for obtaining films with low surface free energies. F-PMMA-b-PDFHM films show lower surface free energy (17.1–17.7 mN m−1) than E-PMMA-b-PDFHM films (17.9–22.9 mN m−1) in each solvent. The surface morphology and roughness determined are strongly controlled by the cast solutions. F-PMMA-b-PDFHM films exhibit a low wettability and high stable surface due to a well-ordered fluorocarbon surface provided by both PDFHM and F–Br groups, and therefore can be developed into a high-performance coating material.
Co-reporter:Junyan Liang, Li Wang, Ling He and Shaodong Sun
Physical Chemistry Chemical Physics 2013 - vol. 15(Issue 26) pp:NaN10929-10929
Publication Date(Web):2013/05/02
DOI:10.1039/C3CP00044C
Two poly(4-vinylpyridine)-b-polystyrene diblock copolymer/silica core–shell nanoparticles (P4VP-b-PS/SiO2 NPs) are developed in this work. Confirmed by DLS analysis and TEM observation, one comprises a SiO2 core surrounded by a P4VP-b-PS shell and the other comprises a P4VP-b-PS core surrounded by a SiO2 shell, which is facilely prepared by the in situ hydrolysis of tetraethyl orthosilicate (TEOS) using cationic P4VP-b-PS micelles obtained in a THF–H2C2O4 (aq, 0.1 mol L−1) mixture and a DMF–H2C2O4 (aq, 0.01 mol L−1) mixture as template, respectively. The SCA, CAH, SA and SEM measurements reveal that one-step deposition of P4VP-b-PS/SiO2 NPs with SiO2 cores formed at a high level of TEOS creates a superhydrophobic surface with an SCA of 160°, a CAH of 2° and an SA of around 4° originating from the formation of a typical micro–nanoscale binary structure (MNBS). For the NPs with SiO2 cores formed at a low level of TEOS, the superhydrophobicity with a SCA of 151°, CAH of 3° and SA of around 5° can be induced by the transition of the surface microstructure from an uneven and discontinuous MNBS, created by a one-step deposition process, to the coexistence of MNBS and a nanoscale structure (NS) after annealing with toluene for 30 min. In contrast, one-step deposition of P4VP-b-PS/SiO2 NPs with P4VP-b-PS cores and SiO2 shells usually results in the inhomogeneous precipitation of SiO2 from bulk P4VP-b-PS along with the production of micro-cracks, with which is impossible to achieve surface superhydrophobicity.
Co-reporter:Liang Junyan, Wang Li, Bao Jingxian and He Ling
Journal of Materials Chemistry A 2015 - vol. 3(Issue 40) pp:NaN20144-20144
Publication Date(Web):2015/07/27
DOI:10.1039/C5TA04428F
Herein, we focus on the creation of durable superhydrophobic and highly oleophobic coating through the casting of multi-dome hydrophobic SiO2 nanoparticles (NPs) modified with fluoroalkylsilane onto a glass plate, followed by coating the surface of pre-stacked particles with another layer of poly(methyl methacrylate)-b-poly(dodecafluoroheptyl methacrylate; PMMA-b-PDFHM). The novel multi-dome hydrophobic SiO2 NPs had re-entrant surfaces covered by methacryloxy groups, which were facilely prepared via a reaction of pristine SiO2 NPs with γ-methacryloxypropyltrimethoxysilane (MPTMS) using an in situ alkali-catalyzed sol–gel process in an n-propanol (NPA) solution. Fluoroalkylsilane-modified SiO2 NPs were prepared by the in situ hydrolysis of 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (FDTES) in a THF–H2C2O4 (aq.) suspension of multi-dome hydrophobic SiO2 NPs. It was found that a decrease in the content of hydrolyzed–condensed FDTES contributed to the reduction in conglutination and the aggregation of multi-dome hydrophobic SiO2 NPs in the obtained coating layer, leading to a relatively loose surface structure with gaps or cavities. In this case, the coating surface supported the Cassie–Wenzel transition state with hexadecane and thus exhibited high oleophobicity with high adhesion. Moreover, superhydrophobicity with water droplets adopting a low-adhesive bouncing Cassie mode was achieved. More importantly, the coating was still well adhered to the glass substrate and demonstrated high oleophobicity and superhydrophobicity after it was subjected to scouring tests using strong base and acid aqueous solutions.
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