甲基丙烯酸3-三甲氧基硅丙酯与苯乙烯乳液共聚合机理

甲基丙烯酸3-三甲氧基硅丙酯(MPS)和苯乙烯的种子乳液聚合反应过程中同时发生自由基共聚合反应和硅氧烷基的水解缩合反应.通过对MPS在不同条件下乳液聚合过程中粒径及其分布的表征、对反应过程中MPS水解产物的跟踪2、9Si固态核磁共振谱(NMR)和红外光谱(FTIR)对反应得到的聚合产物结构的表征对反应过程和机理进行了研究.阐明了不同的反应条件(如水介质的pH值、MPS的加入量和加入方式)下,此种子乳液聚合体系中各类反应的发生场所、各场所下的反应特点、反应中间产物以及由其导致的不同的成核和聚并机理和最终聚合物的微结构.发现根据不同反应条件下的自由基共聚合速率、水解缩合速率以及MPS在粒子相和水相中分配的不同,反应过程呈现差异很大的机理,且得到的乳胶粒形态、微结构也有很大不同.

EMULSION COPOLYMERIZATION MECHANISM OF 3-TRIMETHOXYSILYLPROPYL METHACRYLATE AND STYRENE

Elaboration of hybrid organic-inorganic nanoparticles by heterogeneous polymerization technology arouse highly interest all over the world because of both the direct application in paint,water-borne adhesive,coating formulations and the potential application in bio-technology field.A new type of organicinorganic hybrid materials synthesized by the monomers containing alkoxysilane and vinyl groups is highly evaluated because it improves the chemical bonding between the organic and the inorganic components.However,it is seldom used to synthesis nanoparticles because the hydrolysis and condensation of alkoxysilane groups are hardly controlled in heterogeneous polymerization.In this paper,the mechanism of the emulsion copolymerization of 3-trimethoxysilylpropyl methacrylate(MPS) and styrene is studied.The mechanisms of particle morphology and microstructure formation at different conditions are analyzed by following the resultant of hydrolysis using GC,particle size and its distribution by DLS,and the characterization of the morphology of the latex and the microstructure of the polymer with transmission electron microscopy(TEM),infrared(IR) and solid-state NMR.It is found that the processes are carried out with different mechanism at various operating conditions,and the hydrolysis and condensation rates in the media and the partitioning of MPS are the most important parameters.