核壳结构聚合物乳胶粒的制备与表征

Preparation and Characterization of Polymer Core/Shell Latex Particles

选用苯乙烯和丙烯酸丁酯为聚合单体,改变乳化剂和引发剂用量,制备粒径分布较窄的苯丙乳液。以此为种子胶乳,选用甲基丙烯酸甲酯(MMA)、丙烯酸乙酯(EA)和甲基丙烯酸(MAA)为第2步聚合单体,分别采用批量法和半连续滴加法,制备出具有核壳结构且性能稳定的乳胶粒乳液。通过粒径分析和透射电镜,测试和比较分析两种乳胶粒粒径和形貌,探讨MAA用量对核壳乳液的稳定性和乳胶粒粒径的影响。结果表明:当内核聚合物和外壳单体质量比为5∶2,第2步壳单体中MAA质量分数介于3%至5%时,半连续滴加法制备的乳胶粒粒径分布较窄,乳胶粒形貌规整,分布均匀,草莓型乳胶粒数量较少,随着第2步聚合单体中MAA用量增多,乳液稳定性下降,乳胶粒粒径及分散指数增大。

Seed latex with narrow particle size distribution was first prepared by emulsion polymerization with styrene and butyl acrylate as monomers and varying amounts of emulsifiers and initiators,which was then used to achieve stable core/shell latex with second stage monomers consisting of methyl methacrylate,ethyl acrylate and methacrylic acid（MAA）,by batch and semi-continuous emulsion polymerization.Particles size and morphology of the latexes prepared by the two processes were compared.The effects of methacrylic acid amount on latex properties were studied.Experiment results show that monodisperse core-shell latex particles is obtained when the mass ratio of core/shell is kept at 5 ∶2 with MAA mass content between 3% and 5% in the shell formation monomers.And the particle size distribution of the latexes prepared by semi-continuous technique is narrower than those prepared by batch process.With increasing the amount of MAA in polymerization,the stability of latex deteriorates,and particle size and size distribution increase with more strawberry latex particles.