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在硅溶胶中加入八甲基环四硅氧烷(D4)和偶联剂γ-(2,3-环氧丙氧)丙基三甲氧基硅烷(KH560),以十二烷基苯磺酸(DBSA)催化D4的开环聚合,借助超声强化聚二甲基硅氧烷(PDMS)和偶联剂对硅溶胶的表面改性。将改性硅溶胶及其混合物分散在甲基丙烯酸甲酯(MMA)和丙烯酸丁酯(BA)的混合单体中,实施微滴乳液聚合,制备SiO2/聚丙烯酸酯纳米复合材料。硅溶胶改性阶段的催化剂中和后成为后续微滴乳液聚合的乳化剂,而伴生的PDMS成为有效抑制单体珠滴Ostwald熟化的超疏水剂。采用FTIR、TGA、TEM、马尔文纳米粒度仪、水接触角等测试方法对改性纳米粒、复合胶乳和胶乳薄膜进行表征。结果表明,PDMS和偶联剂在SiO2表面形成了共价键合和包覆,且伴生的PDMS改善了复合胶乳薄膜的表面疏水性,复合粒子是聚合物基体为壳、SiO2纳米颗粒呈海岛分散的(多)核-壳结构形态,SiO2占单体质量分数为3%时,平均粒径约98nm。
Octamethylcyclotetrasiloxane (D4) and coupling agent γ- (2,3-epoxypropoxy) propyltrimethoxysilane (KH560) were added to the silica sol, and dodecylbenzenesulfonic acid (DBSA) catalyzed the ring-opening polymerization of D4 and the surface modification of silica sol by means of ultrasound-enhanced polydimethylsiloxane (PDMS) and coupling agent. The modified silica sol and its mixture are dispersed in a mixed monomer of methyl methacrylate (MMA) and butyl acrylate (BA), and the emulsion polymerization is carried out to prepare the SiO2 / polyacrylate nanocomposite. Neutralization of the catalyst in the silica sol modification stage becomes an emulsifier for the subsequent microemulsion polymerization, and the associated PDMS becomes a superhydrophobic agent that effectively suppresses the monomer bead Ostwald ripening. The modified nanoparticles, composite latex and latex films were characterized by FTIR, TGA, TEM, Malvern nanoparticle analyzer and water contact angle. The results showed that the PDMS and the coupling agent formed covalent bonding and coating on the surface of SiO2, and the accompanying PDMS improved the surface hydrophobicity of the composite latex film. The composite particles were the polymer matrix and the SiO2 nanoparticles were dispersed (Multi) core-shell morphology, SiO2 accounted for monomer mass fraction of 3%, the average particle size of about 98nm.