氯丁胶乳-聚甲基丙烯酸甲酯复合乳胶粒结构形态

以氯丁胶乳（Pa）为种子乳液，甲基丙烯酸甲酯（Pb）为第二单体，采用种子乳液聚合法，制备了氯丁胶乳-聚甲基丙烯酸甲酯复合乳胶粒。 热力学分析表明，当Pb的体积分数Φb＜0.69时，可同时形成Pa-Pb型正核-壳和（Pa＋Pb）分离型乳胶粒，当Φb＞0.69时，形成Pb-Pa型翻转型核壳结构乳胶粒，并伴有Pa-Pb型正核-壳结构乳胶粒的形成。 动力学分析表明，引发剂类型、第二单体的加入方式、种子乳胶粒的交联、单体/聚合物质量比是影响乳胶粒形态的主要因素。 采用水溶性引发剂过二硫酸钾（KPS），以饥饿态方式加入单体，氯丁胶乳 聚甲基丙烯酸甲酯(PCR-PMMA)复合乳胶粒呈现正核-壳结构，以充溢态方式加入单体则不能形成明显的核-壳结构；而以油溶性偶氮二异丁腈（AIBN）为引发剂时，单体无论以充溢态方式加入还是饥饿态加入均倾向于形成翻转核-壳型粒子。 在种子乳胶粒中加入一定量交联剂二缩三乙二醇二甲基丙烯酸酯，有利于形成明显的正核壳结构。 以饥饿态进料，KPS为引发剂时，随着单体用量增加，壳层变厚，仍呈正核-壳结构，与热力学分析结果相吻合；以AIBN为引发剂时，随着单体用量增加，PCR-PMMA复合乳胶粒逐渐由翻转核壳型结构变为互穿结构。

Structure and Morphology of Polychloroprene-Polymethylmethacrylate Composite Latex Particles

Polychloroprene-polymethylmethacrylate(PCR-PMMA) composite latex particles have been prepared through the seed emulsion polymerization with polychloroprene latex(Pa) and methyl methacrylate(Pb) as the seed and monomer, respectively. Thermodynamic analysis results showed that when Φb(volume fraction of polymer b)＜0.69, the Pa-Pb core-shell latex particles and (Pa＋Pb) separated latex particles were formed; while when Φb＞0.69, the inverted Pb-Pa core-shell latex particles and Pa-Pb core-shell latex particles were formed. Kinetic analysis results showed that the initiator type, the monomer feed type, crosslinking of the seed latex particles, and the monomer-to-rubber ratios were major factors influencing the particle morphology. When potassium persulfate was used as the initiator, the monomer-starved conditions led to the formation of normal core-shell particles, whereas flooded-feed MMA could not favor in formation of typical core-shell particle. While when azobisisobutyronitrile(AIBN) was used as the initiator, it led to the formation of inverted core-shell particles no matter if monomer-starved or flooded condition was used. Crosslinking of the polychloroprene seed particles was found to favor to form obvious core-shell PCR-PMMA particles. With the monomer-to-rubber ratio increasing, the shell layer turned thicker, the composite latex particle still showed core-shell structure, which was in agreement with the predicted results of thermodynamic analysis. The inverted core-shell PCR-PMMA composite latex particles were gradually changed to interpenetrating structure as the amount of monomer was increased when AIBN was used.