可UV固化的稳定硅溶胶的制备及其应用

在自制的"凝胶抑制剂"存在下,用正硅酸乙酯和γ-(甲基丙烯酰氧)丙基三甲氧基硅烷为前驱体,丙烯酸羟乙酯为表面修饰剂,在酸性条件下发生共水解-缩合反应,制得可UV固化的有机/无机杂化聚合物(稳定硅溶胶),在60℃干燥箱中贮存28 d未发生凝胶现象。TEM测试结果表明:该杂化聚合物包含微米尺寸的团聚颗粒和纳米颗粒。光固化涂膜性能测试表明:含纳米颗粒的稳定硅溶胶能明显改善涂膜的柔韧性、附着力和硬度。     

Novel UV-autocurable methacrylo-urethane polymeric films derived from m-digallic acid: Preparation and characterization

A new acrylo-urethane film polymer was obtained from methacrylic m-digallic acid derivatives. The product was attained either by thermo- or photopolymerization, and the films were characterized by chemical and spectroscopic methods. Other studies of the properties of these polymers were also performed. The main characteristics found were brief curing times achieved with no photoinitiators, good thermal properties, and optical activity. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2575–2583, 1998     

Study of Cu2+-poly(itaconic acid-co-acrylic acid) complex and copper-polymer nanocomposites

Summary Ultrafine copper particles with diameters in the range of nanometer scale have been prepared in a polymer matrix, using ionic aggregates in Cu²⁺-random poly(itaconic acid-co-acrylic acid) complex precursor films as “microreactors” of controllable size.The morphology and formation of metallic copper particles were studied by transmission electron microscopy and X-ray diffraction techniques. Results from the measurements indicate the copper ions were transformed into nanocrystalline by in situ chemical reduction. It was also found that the polymer chains prohibited the excessive aggregation of the metal atoms and have protective effect on the ultrafine copper particles. Received: 20 May 1998/Revised version: 4 September 1998/Accepted: 16 September 1998     

Preparation of conducting polymer composites: effects of porosity on electrical conductivity

To prepare conducting polymer composites, porous polymethyl methacrylate (PMMA) particles with different specific surface areas were prepared by seeded emulsion polymerization and solvent extraction. The dried porous particles were imbibed with the oxidant solution and adsorbed pyrrole from a solution. The incorporation of pyrrole into the porous particles was achieved by chemical oxidative polymerization. The effects of various polymerization parameters on the electrical conductivity were systematically investigated. The important factors affecting conductivity were the porosity of the host polymer particles and the solvent polarizability. © 1998 SCI.     

Atomic force microscopic (AFM) study on a self-organizing polymer film

Summary The structure of a self-organized polymer film prepared by slow evaporation of organic solvents is studied by atomic force microscopy, and compared with that of polymer film prepared by natural evaporation of organic solvents. AFM studies clearly indicates that there exists a self-organizing process of alkyl chains resulting in the partial interdigitated layer structure under the condition of slow evaporation of organic solvents. Received: 27 July 1998/Revised version: 7 October 1998/Accepted: 2 November 1998     

Influence of spacer groups on grafting ability,curing ability,and film properties of water-based radiation curable latexes

Film-forming polystyrene/poly(n-butyl acrylate-co-glycidyl methacrylate) [PS/P(BA-co-GMA)] core–shell latex particles were prepared via a two-stage emulsion polymerization procedure using a PS latex seed. A delayed addition of GMA was used to locate the functional epoxy groups near the surface of the particles. The surface-bound epoxy groups were used as grafting sites for unsaturated carboxyl functional monomers having the unsaturated groups and the carboxylic group separated by 1, 5, or 10 oxyethylene units. Grafting and curing characteristics and film properties after irradiation were investigated as a function of the number of oxyethylene units. A BA-GMA [P(BA-co-GMA)] copolymer was used as a model system for the core–shell latex particles for quantification of the grafting reactions. The grafting was demonstrated by FTIR and ¹H-NMR spectroscopy. The effects of crosslinking was studied by thermal mechanical analysis and dynamical mechanical analysis. Differential photocalorimetry was also used for evaluation of the curing ability. It was demonstrated that the reagent having five oxyethylene units in the spacer group was grafted onto the polymer backbones to a larger extent than the other two reagents, and a more thoroughly cured film was obtained upon irradiation. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 897–906, 1998     

Preparation and structure control of hollow polymer particles: Influence of seeded emulsion polymerization and alkalization treatment process

Hollow polymer latex particles containing a hydrophilic core were prepared by seeded emulsion polymerization with MAA/BA/MMA/St as comonomers, followed by stepwise alkalization treatment with ammonia. The size and morphology of composite latex particles was determined by TEM. The effects of the seeded emulsion polymerization conditions and alkalization treatment on the size and hollow structure of latex were investigated. The results showed that the optimum content of crosslinking agent in the shell polymers was about 0.5–1.0 wt %, emulsifier was about 0.8–1.1 wt %, and the core/shell weight ratio was 1/7. To obtain uniform hollow latex particles with large size, the starved feeding technique should be adopted in seeded emulsion polymerization, and the neutralization temperature should equal to the T_g of the shell polymer. Then, the obtained polymer particles under this condition had an excellent hollow structure. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Ionic autocrosslinking of water-based polymer latices: A new concept of acid–base interaction occurring upon film formation

Latices of the terpolymer styrene/butyl acrylate/acido-basic monomer, the monomer having either a basic chemical group or an acidic chemical group, were separately prepared by free-radical emulsion polymerization using the nonionic surfactant poly(oxy-1,2-ethanediyl) as steric stabilizer. The basic polymer latices were prepared using 1, 3 or 5% of 2-(dimethylamino)ethyl methacrylate, whereas the acidic polymer latices were prepared using 1, 3 or 5% of acrylic acid (mol% relative to conventional monomers, styrene and butyl acrylate). Blends of the basic and the acidic polymer latices were prepared by simply mixing equal molar quantities of basic and acidic latices. The resulting blends were stable as the steric stabilization prevented unlike particles from colliding. Upon film formation, coalescence of the particles took place, with formation of ionic clusters due to proton exchange from the acidic monomer units to the basic monomer units of neighbouring unlike particles. This constitutes a reversible ionic crosslinking at the periphery of neighbouring particles, which affects the various film properties to different extents.     

Finely dispersed Pt nanoparticles in conducting poly(o-anisidine) nanofibrillar matrix as electrocatalytic material

A new approach based on stepwise oxidation of o-anisidine is explored for generating nanoporous films of poly(o-anisidine), POA and loading of Pt nanoparticles that are subsequently used for electrocatalysis of methanol oxidation are presented and compared with bulk Pt. POA film can easily be prepared by stepwise electro-oxidation procedure with very high porosity consisting of nanofibrillar structure using without templates. Controlled sizes of Pt nanoparticles were entrapped into POA matrix by a two-step process in which first PtCl₆²⁻ ions are sorbed into the pores of polymer matrix followed by electroreduction at −0.55 V in a 0.5 M H₂SO₄ solution. Loading of Pt nanoparticles (10-200 μg/cm²) onto POA matrix were accomplished by varying the concentration (2-10 mM) of the sorbate, i.e., H₂PtCl₆. The sizes of the Pt nanoparticles were determined from TEM analysis and Pt particles were found to be in the range of 10-20 nm. The crystallite phase of Pt particles in POA was examined from XRD pattern. AFM image further supports Pt particles embedded in POA matrix.     

Morphology of a hydrogen-bonded LC polymer prepared by photopolymerization-induced phase separation under an isotropic phase

A hydrogen-bonded LC polymer was prepared by photopolymerization of an LC blend composed of 4-(6-acryloyloxyhexyloxy)benzoic acid (A6OBA) and 4-hexyloxy-4′-cyanobiphenyl (6OCB), containing small amounts of an inhibitor and photoinitiator, at two different temperatures in an isotropic phase. To elucidate the factors determining the morphology of the obtained polymer (poly(A6OBA)), we chose two irradiation temperatures: one in the LC temperature range of the polymer, the other in the isotropic range. We investigated structures of the polymers by optical microscopy and scanning electron microscopy. SEM images showed that the film obtained at the lower temperature consisted of randomly extended fibers having a diameter of ca. 1.0 μm and some branches, whereas the film prepared at the higher temperature was composed of polymer particles with a diameter ca. 1.5 μm. By comparing these results with those of an earlier experiment in which we obtained macroscopically oriented LC fibers by photopolymerization under the LC phase of the blend, we infer the following; (i) the presence of an LC phase in the resulting polymer itself during photopolymerization is necessary for it to form fibrous morphology and (ii) the LC ordering field present prior to photopolymerization is not indispensable for the fibrous morphology but it is for the macroscopic orientation and reduction of the branches in the fibers.     

Morphologic and crystallographic studies on electrochemically formed chromium nitride films

Chromium nitride films were prepared by anodically oxidizing nitride ions at 0.4-1.5 V versus Li⁺/Li on chromium substrates in molten LiCl-KCl-Li₃N systems at 723 K. A crystalline Cr₂N film was successfully prepared at 0.4-1.4 V, and was thicker at more positive electrolytic potential. At 1.5 V, a Cr-N film could be also obtained, but its growth rate was relatively low. The film prepared at 1.5 V consisted of two distinctive layers. The surface layer was amorphous Cr-N containing crystalline CrN particles, and the inner layer was crystalline CrN. It was considered the existence of the amorphous phase suppressed the film growth.     

Preparation and Characterization of Soap-free Cationic Fluorinated Poly-styrene-acrylate Latex with Core-shell Structure

Soap-free cationic fluorinated Poly-styrene-acrylate latex particles with core-shell structure were synthesized by seeded semi-continues emulsion polymerization in the presence of water soluble cationic monomer Methacryloxyethyltrimethyl ammonium chloride (MADAC) and using ethanol as co-solvent. The effects of MADAC dosage and ethanol content on the stability of polymerization process and the properties of the latex particles were studied. The chemical component of the polymer was analyzed by Fourier transform infrared (FTIR). The surface element composition of the prepared copolymer film was analyzed by X-ray photoelectron spectroscopy (XPS), the micro-structure of the prepared latex particles were observed by transmission electron microscopy (TEM). The result shows that cationic soap-free fluorinated poly-styrene-acrylate emulsion with a core-shell structure can be prepared when monomer DAMAC is 6.0 wt% and ethanol is 7.5 wt%.     

Thermal Softening Behavior and Application to Transparent Thick Films of Poly(benzylsilsesquioxane) Particles Prepared by the Sol–Gel Process

Thick films of poly(benzylsilsesquioxane) (BnSiO_3/2) particles, prepared by the sol–gel process, were deposited onto indium-tin-oxide-coated glass substrates by electrophoresis for the application to the micropatterning of the films. BnSiO_3/2 particles were thermally softened and sintered at ∼50°C, which was above the glass transition temperature of the particles. The films prepared by the electrophoretic sol–gel deposition consisted of aggregates of particles with diameters of 0.2–1 μm and were opaque. The film shrank from 2.5 μm to 1.4 μm in thickness and became transparent upon sintering of the particles during heat treatment at temperatures >100°C.     

利用粉煤灰制备矿物聚合材料的实验研究

以粉煤灰为主要原料．并添加煅烧高岭石．以硅酸钠和氢氧化钠作激活剂．制备了矿物聚合材料。制品的3d抗压强度最高可达到39．27MPa。XRD分析表明．铝硅酸盐聚合反应形成的基体相呈非晶态;红外光谱分析表明,材料在固化过程中Si-0、Si-0-Si结构单元的聚合程度得到了提高;扫描电镜照片分析表明,絮凝状的基体相与粉煤灰玻璃体结合紧密．从而为材料形成良好的力学性能提供了结构基础。     

Influence of the nanostructure on charge transport in polyaniline films

Two kinds of polyaniline films with different microstructures were prepared and investigated. One of the films was prepared with polyaniline having nanofiber structure, which was synthesized by rapidly mixed reaction; and the other was prepared with polyaniline having granular particle structure, synthesized by conventional chemical oxidation method. The spectroscopic, electrochemical, and transport properties of the two kinds of films were studied with an interest in an influence of film microstructure on mobilities of charge carriers in polymer films. A clear difference was observed in the mobility versus oxidation level plot between the two kinds of polyaniline films. The results show that nanofiber structure of polyaniline film enhances mobilities, but affect little features of the mobility change induced by oxidation, which implies that although the nanofibers structure facilitates the charge transport in neutral or oxidized films, but it is irrelevant to the evolution of metallic conduction in polyaniline films.     

Particle growth behavior of poly(methyl methacrylate) nanoparticles synthesized by the reversible addition fragmentation transfer living radical polymerization reaction

PMMA nanoparticles with highly mono‐dispersed size distribution were prepared using the RAFT living radical emulsion polymerization technique. A novel sur‐iniferter for the RAFT reaction, DTBA, was synthesized and its chemical structure was identified using several spectroscopic techniques. The relationship between the particle size and the molecular weight of the polymer was investigated measuring the rate of growth of each during formation of particles, and was well explained by the simple random flight molecular conformation model. The particle size increased up to a certain value with decreasing sur‐iniferter concentration and then leveled off, because the surface charge density of the growing particles was not high enough to stabilize the particles in aqueous medium above that value. The core‐shell type di‐block copolymer nanoparticles were also successfully prepared via RAFT reaction. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Colloidal poly(styrene-co-butyl acrylate)/multi-walled carbon nanotubes nanocomposite by heterocoagulation in aqueous media

Colloidal nanocomposite particles were prepared by heterocoagulation of carbon nanotubes (CNTs) dispersion stabilized by cationic hexadecyltrimethylammonium bromide (CTAB) and negatively charged poly(styrene-co-butyl acrylate), P(St-co-BA), latex prepared by conventional emulsion polymerization in aqueous medium with the aid of a flocculant, polyaluminium chloride (PAC), at elevated temperature above the T_g of P(St-co-BA). The hybrid nanocomposite particles were prepared by a simple procedure consisting of mixing two dispersions, particle growth, and stabilization steps. The effects of the surface properties of CNTs, molecular weight of latex polymer, types of flocculants and its optimum concentration were investigated. At a well-controlled condition, the spherical or potato-like particles in the size range of 10-100 μm were achieved. After film formation of the nanocomposite particles, it was able to confirm that CNTs were uniformly distributed without agglomeration in the matrix, resulting in the percolation at a low concentration of CNTs.     

具有硬核—软壳结构的丙烯酸聚合物乳液的研究

利用种子乳液聚合法合成了具有硬核—软壳结构的丙烯酸聚合物微粒子,通过对种子粒子数和最终粒子数的理论计算,并结合最低成膜温度(MFT)的测试结果,描述了聚合物微粒子的聚合过程,同时,还对聚合物乳液的各项性能进行了研究。     

Preparation and Properties of Siloxane-Modified Styrene-Acrylate Latex Particles with Core-Shell Structure

Siloxane-modified styrene-acrylate latex particles with core-shell structure were prepared by two-stage semicontinuous emulsion polymerization using a reactive surfactant. Effects of catalyst dosage, weight ratio of γ-methacryloxypropyltrimethoxysilane (MAPS) to hydroxyl silicone oil (HSO) and siloxane content on the grafting degree of siloxane were studied. The chemical components of the copolymer were characterized by Fourier transform infrared spectra. The micromorphology of latex particles was observed by transmission electron microscopy. The stability properties of emulsion were tested by Ca²⁺, centrifugal, and mechanical stability test. The latex film was studied by water contact angle, water absorption ratio and thermal gravimetric analysis. The results show that siloxane-modified styrene-acrylate latex with core-shell structure can be synthesized using reactive surfactant and the prepared emulsion presents excellent stability. By using hydroxyl silicone oil (HSO) to react with silane coupling agent MAPS during emulsion polymerization, HSO can be located in the side chain of the polymer and endow the latex film with excellent stabilities.     

Crosslinking of isocyanate functional acrylic latex with telechelic polybutadiene. I. Synthesis and characterization

An ambient curable isocyanate functional acrylic latex was synthesized by incorporating dimethyl meta-isopropenyl benzyl isocyanate (TMI®), an isocyanate monomer, into styrene/n-butyl acrylate copolymer. An artificial latex of amino-terminated telechelic polybutadiene was prepared and blended with the acrylic latex as a curing agent. The isocyanate content in the blended latex was determined by titration and FTIR measurements. The latex blend properties, in terms of particle size and latex viscosity, and the latex film properties, in terms of stress–strain behavior and solvent swelling behavior, showed no significant change after 30 days' storage of the latex blend at 50°C. The good storage stability was attributed to the stable nature of the latex blend in which there was little chance for the isocyanate-containing particles to come into contact with the curing agent particles, thus preventing premature contact of the acrylic chains with the telechelic chains. The reactivity of different functional groups in the telechelic polymer was studied; the amino group was found to be the most reactive toward the TMI. In addition, a shorter chain telechelic crosslinker was found to result in a higher degree of crosslinking, but this was more intraparticle than interparticle in nature. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 965–975, 1998