SiO_2溶胶在微滴乳液聚合中的原位纳米复合

Nanocomposites prepared in-situ miniemulsion polymerization with silica sol

提出将正硅酸乙酯(TEOS)的非水sol-gel反应与单体的微滴乳液聚合技术相结合,制备聚丙烯酸酯/二氧化硅纳米复合乳液。首先采用凝胶时间的测定与动态光散射等手段研究TEOS在甲酸催化下的非水sol-gel反应动力学,表明当甲酸/TEOS的摩尔比大于6时,有利于形成颗粒状纳米二氧化硅溶胶。以硅烷偶联剂KH-570对非水溶胶原位改性,然后引入丙烯酸酯共聚单体中,研究硅溶胶的存在对单体微滴乳液聚合的影响。结果表明,聚合动力学与单体的微滴乳液聚合基本相似,但二氧化硅的引入改变了单体微滴的均一性和剪切分散的稳定性,导致乳胶粒径逐渐增大,粒径分布变宽。复合乳胶粒是若干无机粒子以微相区被包覆于有机聚合物中的纳米复合结构形态。

Polyacrylate/SiO2 nanocomposites were prepared by combining non-aqueous sol-gel reaction of tetraethylorthosilicate（TEOS）and miniemulsion polymerization of acrylates.Firstly,kinetics of non-aqueous sol-gel process of TEOS was investigated by gelation time measurement and dynamic light scattering（DLS）.The results showed that it was beneficial to get spherical silica particles if molar ratio of formic to TEOS was more than 6.Then the silica sol was modified by silane coupling agent 3-methacryloylpropyltrimethoxysilane（KH-570）.The miniemulsion polymerization of acrylates in the presence of modified silica sol in the comonomer droplets was studied.The polymerization kinetics was similar as normal miniemulsion polymerization.Introducing silica sol reduced the homogeneity of monomers droplets and the stability of the dispersed droplets,so that with increasing the contents of silica sol,the particle sizes increased and the particle size distribution became wider.The latex particle morphologies of the nanocomposites were the structure of several silica microdomains encapsulated by polyacrylate.