Properties of organic–inorganic composite materials prepared from acrylic resin emulsions and colloidal silicas

To design an organic–inorganic composite material with colloidal silica as the inorganic component, an acrylic resin emulsion and an organic silane hybridized acrylic resin emulsion were prepared by emulsion polymerization. The organic–inorganic composite films were prepared by blending the emulsion and the colloidal silica. The contact angles for water, gloss at 60°, and the transparencies of those films were measured. The dispersion state of colloidal silica in films was observed with a scanning electron microscope (SEM) and a transmission electron microscope (TEM). From these results, the contact angle for water of the organic–inorganic composite film obtained from the silane hybridized acrylic resin emulsion was lower than that of the organic–inorganic composite film obtained from an acrylic resin emulsion. The contact angles for water in organic–inorganic composite films with colloidal silicas were lower than those of the films without the colloidal silicas. The films prepared from silane hybridized acrylic resin emulsion composites with colloidal silicas of less than 100 nm were more hydrophilic. SEM and TEM observations demonstrated that some aggregations of the small colloidal particle silica were densely dispersed on the film surface. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2051–2056, 2006     

Fabrication of chemically bonded polyacrylate/silica hybrid films with high silicon contents by the sol–gel method

Polyacrylate/silica hybrid latexes (PAES) with high silicon contents (up to 21%) were prepared by directly mixing colloidal silica with polyacrylate emulsion (PAE) modified by a silane coupling agent. Sol–gel-derived organic/inorganic thin films were obtained by addition of hydrophilic co-solvents to PAES and subsequent drying at room temperature. The effects of co-solvents and γ-methacryloxypropyltrimethoxysilane (KH570) content on the properties of PAES films were investigated. Dynamic light scattering (DLS) data indicated that the average diameter of PAES (96 nm) was slightly larger than that of PAE (89 nm). TEM photo revealed that colloidal silica particles were dispersed uniformly around polyacrylate particles and that some of the colloidal silica particles were adsorbed on the surface of PAE particles. The data of crosslinking degree and FT-IR spectra confirmed that the chemical structure of the PAES changed to form Si–O–Si-polymer crosslinking networks during the film formation. AFM photos, contact angle for water, and XPS analysis showed that the polyacrylate/inorganic hybrid films with high silicon contents were formed by the co-solvent-mediated, sol–gel method and that the Si-based polymers were uniformly distributed on the surface of the dried films. TGA data demonstrated that the PAES films display much better thermal stability than the PAE counterpart.     

有机无机杂化丙烯酸乳液的制备及涂膜性质研究

为了制备一种疏水抗覆冰涂料,采用种子半连续乳液聚合法,通过添加乙烯基三乙氧基硅烷(A-151)和纳米二氧化硅粉末,分别合成了纯丙乳液、硅丙乳液和纳米二氧化硅/硅丙复合乳液,并将乳液涂覆在铝片表面,室温干燥成膜.利用红外光谱、粒度分析、扫描电镜等测试手段对3种乳液及其涂膜性能进行表征.结果表明:添加A-151可以使涂膜交联度提高到95%,吸水率降低到5%;添加纳米二氧化硅,可提高乳液涂膜的热分解温度,使乳液粒径大小分布均匀.此方法中,A-151和纳米二氧化硅改性的乳液涂膜疏水作用有限,仅使接触角增加到约30°.     

高硅含量有机无机杂化乳液的制备和溶胶-凝胶驱使成膜

A novel polymer/SiO2 hybrid emulsion (PAES) was prepared by directly mixing colloidal silica with polyacrylate emulsion (PAE) modified by a saline coupling agent. The sol-gel-derived thin films were obtained by addition of co-solvents into the PAES. The effects of γ-methacryloxypropyltrimethoxysilane (KH-570) content and co-solvent on the properties of PAES films were investigated. Dynamic laser scattering (DLS) data indicate that the average diameter of PAES (96 nm) is slightly larger than that of PAE (89 nm). Transmission electron microscopy (TEM) photo discloses that colloidal silica particles are dispersed uniformly around polyacrylate particles and some of the colloidal silica particles are adsorbed on the surface of PAE particles. The crosslinking degree data and Fourier transform infrared (FT-IR) spectra confirm that the chemical structure of the PAES is changed to form Si-O-Si-polymer crosslinking networks during the film formation. Atomic force microscope (AFM) photos show the solvent induced sol-gel process of colloidal silica and the Si-based polymer distribution on the film surface of the dried PAES. Thermogravimetric analysis (TGA) curves demonstrate that the PAES films display much better thermal stability than PAE.     

Transparent polysilicone coatings as protecting films for gold commemorative coins

Novel transparent organic silicone resin coatings were successfully prepared through the reaction between the alkoxy groups of methyltrimethoxy‐silane (MTMS) and γ‐aminopropyltriethoxysilane (APTES) and hydroxyl groups of hydroxyl terminated silicone oil (HTSO). The influences of different monomer feed mass ratio on the coating properties were investigated via measuring the hydrophobicity and hardness of coating films. The coating films were characterized with IR, UV, TG, scanning electron microscope (SEM), and automatic contact angle meter. Some properties of coating films, such as adhesion, impact resistance, and wear‐resistance, were also evaluated. The results indicated that these coating films formed on the surfaces of gold commemorative coins possessed some good properties including high hydrophobicity, high water contact angles, high light transmittance, good heat‐resistance, adhesion, hardness, and weatherability, etc. Moreover, the uniform, clear, transparent, and dense coating films did not cover the symphony surface patterns or affect the metallic luster. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Chitosan-hybridized acrylic resins prepared in emulsion polymerizations and their application as interior finishing coatings

Chitosan was used to introduce formaldehyde adsorption abilities into an emulsion binder for interior finishing coatings. Chitosan-hybridized acrylic emulisions were prepared by two methods. To produce stable chitosan-hybridized acrylic emulsions, the pre-emulsion dropping method is superior to the monomer dropping method. The adsorption performances for fonnaldehyde in chitosan-hybridized acrylic resin films increased with increasing chitosan contents; the films also had adsorption abilities for hydrogen sulfide and ammonia. Tensile strengths and elongation at breaking points decreased with increasing chitosan contents. Interior finishing coatings made from chitosan-hybridized acrylic resin emulsions have the qualities necessary for an interior finishing coating and showed excellent adsorption abilities for formaldehyde.     

Characterization of UV curable hybrid hard coating materials prepared by sol-gel method

Using sol-gel method, UV-curable urethane acrylate resin system was hybridized with inorganic silicate network to produce hybrid coating materials with high anti-abrasive property. In preparation of acrylate/SiO₂ hybrid materials, various acrylic reactants with multi-functional groups in addition to urethane acrylate oligomer as the main network former were employed to obtain more densified organic network structure with a high degree of cross-linking. As a silane coupling agent, 3-methacryloxypropyl-trimethoxysilane (MPTMS) was used to promote interfacial attraction between UV-cured organic acrylate resin and inorganic silicate component in the hybrid. The addition of MPTMS offered significant effect on the improvement of phase compatibility between organic and inorganic phases, which resulted in stable and homogeneous morphology with a dispersion of nano-sized fine silica particles. The results of morphological observation, glass transition behavior, and optical transparency for the hybrid gels provided an evidence for the increased interfacial attraction between two phases. From the Taber abrasion test for the hybrid coating films, it was revealed that there existed optimal ranges of inorganic silicate precursor TEOS and silane coupling agent MPTMS contents for the preparation of UV cured acrylate/SiO₂ hybrid with high abrasion resistant property.     

The effect of nonionic monomer HAM on properties of cationic surfactant‐free acrylic/alkyd hybrid emulsion

A series of cationic acrylic/alkyd resin (CPAAR) hybrid emulsions was successfully prepared through surfactant‐free emulsion polymerization, using methacryloxyethyltrimethyl ammonium chloride, methyl methacrylate, butyl acrylate and alkyd resin as reaction monomers. And nonionic N‐hydroxymethyl acrylamide (HAM) of different content was simultaneously incorporated into the CPAAR backbone. The structure of CPAAR copolymer was characterized by Fourier transform infared spectrometer, and then the effect of HAM content on properties of CPAAR emulsions was studied by particle size analyzer, transmission electron microscopy and rheometer. In addition, thermal properties, water absorption and contact angle of CPAAR latex films were also investigated. The results showed that the CPAAR emulsions prepared with 4.9 wt % HAM displayed smallest average particle size of 92.2 nm. As HAM content increased from 0 to 19.6 wt %, the initial viscosity of the emulsions increased from 22.48 to 53 mPa.s. At the same time, the emulsions transferred from Newtonian fluid to pseudoplastic fluid, and a transition from viscous liquid to elastic liquid was also detected. Meanwhile, the degradation temperature at 5% weight loss increased by 30.59°C. In addition, with increasing HAM content from 0 to 4.9 wt %, the water absorption and surface free energy of films increased by 4.42% and 5.02 mJ m^?2, respectively. However, the water absorption and surface free energy kept almost invariable with further increase in HAM content. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41406.     

油性介质中组装二氧化硅胶体晶体薄膜

报道厂一种由粒径大于700nm的SiO2微球组装胶体晶体薄膜的方法。以一种密度较大的疏水性有机物替代水或醇类为分散剂,通过对SiO2微球表面进行疏水性处理改善其在油性介质中的分散性,采用改进的垂直沉积法在油性分散剂中制备SiO2胶体晶体。用扫描电子显微镜、红外光谱仪和紫外－可见光谱仪对SiO2胶体晶体薄膜的形貌、结构和光学性能进行了观察测试。结果表明;较大密度的分散剂能有效降低SiO2微球的沉降速度,组装成直径在700～2000nm范围的SiO2微球的胶体晶体。获得的SiO2光子晶体具有长程有序结构,并在近红外区具有显著的光子频率带隙。     

支化型有机硅/丙烯酸酯共聚乳液的合成及其性能

采用种子半连续乳液聚合,以γ-甲基丙烯酰氧基丙基三甲氧基硅烷(MPS)为交联单体,以具有支化型大体积疏水基团的有机硅单体γ-甲基丙烯酰氧基丙基三(三甲基硅氧基)硅烷(MATS)为功能单体,与丙烯酸丁酯和甲基丙烯酸甲酯进行乳液共聚,合成了稳定的交联型高硅含量硅丙乳液。对乳液聚合过程及聚合物膜性能的测试结果表明,随聚合体系中MATS用量由0增加到占单体总质量的10%,乳胶粒子的z-均粒径(Dz)由133.5 nm减小到123.7 nm,粒径多分散指数由1.150减小为1.131;聚合物膜的水表面接触角由61°增大到78,°48 h吸水率由5.9%降低为2.5%。     

水性无机建筑涂料热贮存稳定性的影响因素探讨

以胶体二氧化硅溶液和改性液态硅酸钾为主要无机成膜物质,苯丙乳液为有机改性剂、合成硅酸镁锂为增稠防沉剂、以金红石型钛白粉、煅烧高岭土、重质碳酸钙、滑石粉等为颜填料制备了一种性能优异、热贮存稳定性良好的水性无机建筑涂料,讨论了胶体二氧化硅和改性硅酸钾的种类、不同增稠剂、改性有机高聚物乳液、颜填料等对其热贮存稳定性的影响,并对涂层的施工性能,耐洗刷性能、耐水、耐碱性能等进行了评估。     

水性聚氨酯/硅溶胶复合涂层的制备与性能

将水性聚氨酯乳液与硅溶胶共混,制备了水性聚氨酯/硅溶胶复合乳液。采用TEM、激光粒度分析仪、流变仪、ATR-FTIR、TG对复合乳液及其涂膜进行表征,探讨了硅溶胶用量对复合涂膜性能的影响。ATR-FTIR分析表明,聚氨酯分子和硅溶胶之间可以形成氢键,但不存在化学键结合;TEM、激光粒度分析测试表明,硅溶胶质量分数的增加,使复合乳液粒子粒径增大,粒度分布变宽,当硅溶胶质量分数20%后,乳胶粒子间易发生团聚;流变分析发现,加入硅溶胶后,乳液的表观黏度(ηa)增大,假塑性增强。性能测试结果表明,硅溶胶质量分数20%时,复合乳液具有好的储存稳定性,复合涂膜表现出很好的热稳定性,48 h吸水率仅为18.94%,同时表现出很好的耐溶剂性能,拉伸强度达到28.98 MPa,铅笔硬度达2H,附着力0级。     

水性聚氨酯的改性研究

分别采用丙烯酸酯、环氧树脂合成2种不同的改性水性聚氨酯,比较了改性前后及2种不同的改性水性聚氨酯在乳液、涂膜性能及粘接性能方面的差异。结果表明,改性后的水性聚氨酯综合性能明显提高,其中环氧树脂改性水性聚氨酯(EPU)在固化交联后涂膜的耐水、耐溶剂及力学性能又明显好于丙烯酸酯改性水性聚氨酯(PUA),其粘接强度与溶剂型聚氨酯相当;而采用丙烯酸酯改性的水性聚氨酯PUA乳液稳定性好于EPU乳液。     

Surface modification of silica particles assisted by CO2

This paper reports the synthesis of coating silica particles, in order to design hybrid materials with hydrophobic surface properties. The silica particles were prepared in basic conditions under atmosphere of carbon dioxide (CO₂), using tetraethylorthosilicate (TEOS) as a precursor and octyltriethoxysilane (OTES) as a surface modifying agent. It was demonstrated that the contact angles of silica hybrid films could be changed by varying temperature and pressure of CO₂. The investigation of the prepared hybrid materials by dynamic light scattering (DLS) and environmental scanning electron microscopy (ESEM), respectively, showed that they consisted mainly of particles with a diameter of 100–250 nm. Fourier transform infrared (FT-IR) spectra indicate that the interaction between the coupling reagents, at different conditions, is mainly through chemical bonding.     

The structure and properties of acrylic‐polyurethane hybrid emulsions and comparison with physical blends

Aqueous acrylic‐polyurethane hybrid emulsions were prepared by semibatch emulsion polymerization of a mixture of acrylic monomers (butyl acrylate, methyl methacrylate, and acrylic acid) in the presence of polyurethane dispersion. Equivalent physical blends were prepared by mixing acrylic emulsion and polyurethane dispersion. The weight ratio between acrylic and polyurethane components varied to obtain different emulsion properties, microphase structure, and mechanical film properties of hybrid emulsions and physical blends. Particle size and molecular mass measurements, scanning electron microscopy, glass transition temperature, and rheological measurements performed characterization of the latex system. The mechanical properties were investigated by measuring tensile strength and Koenig hardness of dried films. The experimental results indicate better acrylic‐polyurethane compatibility in hybrid emulsions than in physical blends, resulting in improved chemical and mechanical properties. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 67–80, 2000     

Preparation of organic–inorganic nanocomposites with core‐shell structure by inorganic powders

Organic–inorganic nanocomposites with core‐shell structure were prepared in two steps. In the first step, the latex particles in the semibatch emulsion polymerization of butyl methacrylate (BMA), in the presence of methacrylic acid (MAA), were prepared. Small amounts of acrylic acid incorporated into the latex to have better interaction between the surface of particles and inorganic phase. MAA also increased the latex stability and decreased the amount of coagulum. In the second step, the core‐shell structures were prepared by coating the latex particles with three types of inorganic powders. Pectin coated precipitated calcium carbonate, alumina, and silica. The examinations show that pectin‐coated calcium carbonate has the best response than other types of calcium carbonate. Alumina was the second type of inorganic powder that was used for coating the core particles. Silicagel and fumed silica (Aerosil) were used for coating by silica. Scanning electron microscopy and transmission electron microscopy showed the particle morphology and the core‐shell structure, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

聚丙烯酸酯／纳米SiO_2复合压敏胶乳液的性能及影响因素

采用原位乳液聚合法成功制备了高性能的聚丙烯酸酯／纳米SiO2有机-无机复合压敏胶乳液。TEM 及粘接性能测试的结果表明:纳米SiO2能有效地被分散到纳米量级并以此量级与原位生成的聚丙烯酸酯复合,纳米SiO2的引入能同时提高乳液的内聚力和剥离强度。考察了纳米SiO2含量、硬单体和功能单体的用量及乳化剂的加入方式等对复合乳液压敏性能的影响。所得复合乳液放置3个月后仍有理想的压敏性能,存贮稳定性良好。     

Core-shell-structured silica/polyacrylate particles prepared by Pickering emulsion: influence of the nucleation model on particle interfacial organization and emulsion stability

This work reports a new evidence of the versatility of silica sol as a stabilizer for Pickering emulsions. The organization of silica particles at the oil-water interface is a function of the nucleation model. The present results show that nucleation model, together with monomer hydrophobicity, can be used as a trigger to modify the packing density of silica particles at the oil-water interface: Less hydrophobic methylmethacrylate, more wettable with silica particles, favors the formation of core-shell-structured composite when the composite particles are prepared by miniemulsion polymerization in which monomers are fed in batch (droplet nucleation). By contrast, hydrophobic butylacrylate promotes the encapsulating efficiency of silica when monomers are fed dropwise (homogeneous nucleation). The morphologies of polyacrylate-nano-SiO₂ composites prepared from different feed ratio of methylmethacrylate/butylacrylate (with different hydrophobicity) and by different feed processes are characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) techniques. The results from SEM and TEM show that the morphologies of the as-prepared polyacrylate/nano-SiO₂ composite can be a core-shell structure or a bare acrylic sphere. The stability of resulting emulsions composed of these composite particles is strongly dependent on the surface coverage of silica particles. The emulsion stability is improved by densely silica-packed composite particles.     

Influence of the coating method on the formation of superhydrophobic silicone–urea surfaces modified with fumed silica nanoparticles

Effect of the coating method on the formation of superhydrophobic polydimethylsiloxane–urea copolymer (TPSC) surfaces, modified by the incorporation of hydrophobic fumed silica nanoparticles was investigated. Four different coating methods employed were: (i) layer-by-layer spin-coating of hydrophobic fumed silica dispersed in an organic solvent onto TPSC films, (ii) spin-coating of silica–polymer mixture onto a glass substrate, (iii) spray coating of silica/polymer mixture by an air-brush onto a glass substrate, and (iv) direct coating of silica–polymer mixture by a doctor blade onto a glass substrate. Influence of the coating method, composition of the polymer/silica mixture and the number of silica layers applied on the topography and wetting behavior of the surfaces were determined. Surfaces obtained were characterized by scanning electron microscopy (SEM), white light interferometry (WLI) and advancing and receding water contact angle measurements. It was demonstrated that superhydrophobic surfaces could be obtained by all methods. Surfaces obtained displayed hierarchical micro-nano structures and superhydrophobic behavior with static and advancing water contact angles well above 150° and fairly low contact angle hysteresis values.     

Preparation and characterization of phosphine oxide containing organosilica hybrid coatings by photopolymerization and sol–gel process

A series of UV-cured organic–inorganic hybrid coating materials containing up to 20 wt.% silica were prepared by sol–gel method from tetraethoxy silane (TEOS) which is used as the primary inorganic precursor, and diallylphenylphosphine oxide monomer (DAPPO), aliphatic urethane diacrylate resin (Ebecryl 210) are employed as the source of the organic components. In addition, methacryloxypropyltrimethoxy silane (MAPTMS) was used as both a secondary inorganic source and a silane-coupling agent to improve the compatibility of the organic and inorganic phases. The DAPPO content in all the coating formulations were from 0 to 20 wt.%. The physical and mechanical properties such as gel content, hardness, adhesion, gloss, contact angle as well as tensile strength were measured. These measurements revealed that all the properties of the hybrid coatings improved effectively, in case of adding the sol–gel precursor and DAPPO monomer content in the hybrid systems. The photo-calorimetric-DSC studies showed that the double bond conversion of the hybrid coatings was faster than the coating materials without silica. The thermal stabilities of the UV-cured hybrid materials were investigated by thermogravimetric analysis. The results showed that the addition of sol–gel precursor and DAPPO into the organic network also improves the thermal-oxidative stability of the hybrid coating materials. The surface morphology was also characterized by scanning electron microscopy (SEM). SEM studies indicated that inorganic particles were dispersed homogenously throughout the organic matrix.