SiO2/聚甲基丙烯酸叔丁酯核壳复合微粒的制备与表征

以甲基丙烯酸-3-(三甲氧基硅基)丙酯(MPS)修饰的SiO2胶体粒子为种子,甲基丙烯酸叔丁酯(tBMA)为单体、十二烷基硫酸钠(SDS)为乳化剂,采用种子乳液聚合法制备了SiO2/聚甲基丙烯酸叔丁酯的核壳复合微粒。微粒经水解后形成具有pH敏感性的无机/有机复合微粒。研究了影响核壳复合微粒形态结构的因素,结果发现,控制SiO2种子乳液的质量分数在1.5%～2%,可避免聚合过程中生成纯聚甲基丙烯酸叔丁酯乳胶粒子;反应体系中乳化剂SDS的用量超过质量分数0.3%时,易形成纯聚合物乳胶粒子;SDS用量低于质量分数0.15%时,生成的核壳复合微粒易产生团聚;单体和交联剂用量升高,核壳复合微粒的壳层厚度增加,用量过高会导致核壳复合微粒出现团聚现象,并且有纯聚合物乳胶粒子生成。采用TEM、NMR和FTIR及接触角测试技术分析结果表明,复合微粒是由SiO和聚甲基丙烯酸叔丁酯组成的核壳结构微粒。

Preparation and Characterization of Core/Shell Composite Microparticles with Silica Core and Poly(tert-butylmethacrylate) Shell

Core/shell composite microparticles with silica nanoparticle as core and crosslinked poly(tert-butylmethacrylate) as shell were prepared by seed-emulsion polymerization utilizing 3-(trimethoxysilyl)propyl methacrylate(MPS) modified silica particles as seeds,tert-butylmethacrylate as monomer and sodium dodecyl sulfate(SDS) as emulsifier.The microparticles were transformed into pH-sensitive inorganic/organic composite microparticles by hydrolysis.The factors affecting the morphological structure of the composite microparticles were investigated,and it was found that the formation of pure poly(tert-butylmethacrylate) latex particles in the polymerization process could be avoided by controlling the solid content of the silica seed emulsion in the range from 1.5% to 2%.Pure poly(tert-butylmethacrylate) latex particles tended to be formed when the content of SDS exceeded 0.3%,while the core/shell composite microparticles were readily flocculated if the content of SDS was below 0.15%.Their shell thickness was enhanced as the amount of the monomer and crosslinker was increased,but their excessive use led to the formation of pure poly(tert-butylmethacrylate) latex particles and the flocculation of the formed core/shell composite microparticles.The core/shell morphological structure and chemical composition of the composite microparticles were confirmed by TEM,NMR,FTIR and contact angle analysis results.