表层功能化核壳型聚乳酸增韧粒子的合成及其增韧机理研究

聚乳酸（PLA）韧性差的缺点严重限制了其在更多领域的应用。本项目拟利用种子乳液聚合合成以聚丙烯酸丁酯为核、聚甲基丙烯酸甲酯为壳的核壳型增韧粒子，并在壳层聚合时引入功能基团，改善与PLA基体的界面相容性。凭借软核-硬壳的内外层特殊结构，所合成的表层功能化核壳粒子兼具橡胶和刚性粒子增韧的共同优势，在保证力学强度和耐热性的同时，显著提高PLA的韧性。拟系统研究种子乳液聚合中核壳粒子的核壳比、粒子尺寸、粒径分布、壳层厚度与反应条件的相互关系，获得核壳粒子形态结构的生成和演变规律；探明功能化核壳粒子的结构特征对PLA相容性、界面结晶、断裂形貌和力学性能的影响规律，并将所获得微观结构信息与宏观力学性能变化相关联，揭示核壳粒子增韧PLA的内在机理，为制备高韧性PLA复合材料提供理论基础和实验依据。

The inherent brittleness of polylactic acid (PLA) severely limits its wider application. In this proposal, the seed emulsion polymerization is planned to synthesize the core-shell structure particles (CSPs), in which the core layer is composed by poly(butyl acrylate) and the shell layer is poly(methyl methacrylate). During the polymerization of the shell layer, the functional groups are introduced to improve the interfacial compatibility with PLA matrix. By dint of the soft core and hard shell structure, CPSs with the functional surface are attractive in terms of toughening compared to rubber materials and rigid particles. Thus, the significant enhancement in the toughness of PLA is achieved with a minimal effect on the mechanical performance and heat resistance. The ratio of core to shell, particle size, size distribution, and shell thickness are correlated with the synthesis conditions so as to obtain the formation and evolution rules of morphology and structure of CSPs. Effects of morphology and structure of CSPs on compatibility, interfacial crystallization, fracture morphology, and mechanical performance of PLA are investigated systematically. By associating the microstructure information with mechanical properties, the toughening mechanism of CPS towards PLA is revealed. The obtained results above will provide theoretical guidelines and experiment basis for manufacturing the PLA products with high toughness and superior performance.