一步法制备窄粒径分布亚微米级乳胶粒子及其聚并成核与增长机理

传统的亚微米级乳胶粒子通常采用分步种子乳液聚合、乳胶粒子(＜100nm)附聚或无皂乳液聚合方法进行制备，它们的缺点是聚合周期长、工艺繁琐、乳液稳定性差和粒径分布宽。本课题采用间歇乳液聚合方法(一步法)，通过调控乳液的离子强度和乳胶粒子中聚合物与反应介质之间的界面张力来控制乳胶粒子的稳定性，促使其发生聚并，直接制备窄粒径分布的亚微米级乳胶粒子。在不同的电解质含量、单体/水比、聚合物与反应介质之间的界面张力下，通过研究乳胶粒子的粒径及分布、粒子数目、乳化剂分子的表面覆盖率、粒子微观结构及其稳定性随单体转化率的变化规律，揭示乳胶粒子发生聚并的动力学本质原因，构建有皂乳液聚合体系乳胶粒子聚并成核与增长机制的物理模型，阐明乳胶粒子成核机制、粒子微观结构和乳液性能之间的关系。本课题为设计并制备窄粒径分的亚微米级乳胶粒子和髙固含量乳液提供了新的方法和思路，对丰富经典乳液聚合的粒子成核机理具有重要意义。

Traditional sub-micron latex particles was usually prepared by multi-stage seed emulsion polymerization, physical(or chemical) agglomeration of small latex particles with the size less than 100nm, or soap-free emulsion polymerization methods. The major shortcomings of these methods were as following, a long polymerization period, a complicated process, a weak latex stability and a wide particle size distribution. In this research, the latex particles would coagulate by regulating latex particles stability with varying the latex ion strength and the interface tension between polymer and reaction medium, and the sub-micron latex particles with narrow size distribution were directly prepared by batch emulsion polymerization. Under different electrolyte concentration, monomer/water ratios or the interface tension, the variation of particle size and distribution, particle number, particle surface coverage ratio, particle morphology stability with monomer conversion were investigated. The dynamic essence of coagulation of latex particles is revealed, and a physical model about coagulation nucleation and particle growth is proposed and established. The relationship among the nucleation mechanism and particles microstructure and latex performance would be clarified. This research have important academic value for perfecting and developing classical theory of emulsion polymerization. and proposed a new method for preparing sub-micron latex particles with narrow size distribution and high solid content latex.