梯度核壳乳液的合成研究

采用多步乳液聚合法合成具有核/中间层/壳梯度结构的纯丙乳液，并对影响聚合物粒子核壳结构的主要因素进行了探讨。实验发现硬单体和软单体在选用多步乳液聚合技术时，可形成具有梯度的硬核软壳结构型乳液，降低了乳液的最低成膜温度；采用壳预乳化法添加乳化剂可使其在不同的反应阶段得到合理分配，有利于维持反应体系稳定，并避免在反应后期生成新粒子；当乳化剂用量为3%时，凝聚率仅有1%，所得乳液粒径在100nm左右且粒径分布均匀。同时，通过粒度仪和透射电镜（TEM）对粒子结构进行分析并验证了其梯度核壳结构形态。

Studies of graded core-shell emulsion

An acrylate emulsion with a graded core-mesosphere-shell structure has been synthesized by multi-stage emulsion polymerization,and the main factors affecting the core-shell structure of the polymer particles have been discussed.The experimental results show that use of multi-stage emulsion polymerization allows the synthesis of a graded core(hard)-shell(soft) emulsion with a hard monomer (methyl methacrylate) and a soft polymer(butyl acrylate) and the minimum film forming temperature(MFT) can be reduced significantly.Emulsifiers can be well distributed at different stages by means of shell pre-emulsification which can improve the stability of the system,and avoid the formation of new small particles in the subsequent reaction process.When the amount of emulsifier is 3%(based on the amount of monomer),the coagulation rate is only 1% and the particle size is about 100 nm with a narrow distribution.The structure of the polymer particles was analyzed using a particle size analyzer and by transmission electron microscopy(TEM),which clearly demonstrate the presence of the graded core-mesosphere-shell structure.