甲基丙烯酸甲酯/纳米SiO_2粒子分散液的细乳化和细乳液聚合

对包含纳米SiO2粒子的甲基丙烯酸甲酯(MMA)的细乳化和细乳液聚合行为进行了研究.发现在超声细乳化过程中,90%以上的分散于MMA相的纳米SiO2粒子将从油相逃逸到水相.采用甲基丙烯酸3-(三甲氧基甲硅烷基)丙酯(MPS)偶联剂处理SiO2粒子,可以增加其表面亲油性,抑止这种逃逸,经测定几乎全部SiO2粒子在超声细乳化后仍稳定停留在细乳化亚微液滴中.通过进一步细乳液聚合,得到了分散稳定、界面清晰的包裹有纳米SiO2粒子的聚甲基丙烯酸甲酯复合粒子乳液.

MINI-EMULSIFICATION AND MINI-EMULSION POLYMERIZATION OF METHYL METHACRYLATE/NANOSILICA DIPSERSION

The mini-emulsification and mini-emulsion polymerization of methyl methacrylate(MMA)/nanosilica dispersion were investigated.The mini-emulsification was carried out by ultrasonic treatment.It was found that more than 90% silica particles would be escaped from submicron MMA droplets to water phase after ultrasonic treatment when MMA/unmodified silica dispersion was used.Almost all silica particles stably stayed in MMA droplets when silica particles were treated by 3-(trimethoxysilyl)propyl methacrylate(MPS) coupling agent at 40℃ for 24 h before being dispersed in aqueous phase.This was caused by the effective grafting of MPS onto silica particles,and the decrease of hydrophilicity of silica particles.Poly(methyl methacrylate)/nanosilica composite latex particles were prepared by mini-emulsion polymerization of silica-containing MMA using sodium lauryl sulfate(SDS) as the surfactant and hexadecane(HD) as the costabilizer.The composite latex particles were dispersed stably,the surfaces of composite latex were sleek and the silica particles could hardly be found in the water phase.It was considered that the silica particles had been encapsulated in the composite particles.