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利用高倍光学显微镜、库尔特粒径测试仪、TEM及zeta电位跟踪观测了苯乙烯(St)与甲基丙烯酸甲酯(MMA)在聚乙二醇(PEG)水溶液无皂乳液共聚过程中的粒径、粒径分布以及zeta电位变化.聚合物粒径会经历由小到大(某些粒径甚至超过1000μm,分布在0.04～2000μm的极宽范围内),再由大变小(形成的数均分布在0.04～0.18μm)过程,且粒径分布也由宽变窄,最终粒径数均分布集中在0.04～0.18μm窄范围内.结合聚合转化率数据,根据PEG水溶液中进行的St/MMA无皂乳液共聚粒径变化过程,以及zeta电位在聚合过程中异于普通无皂乳液的现象,认为该体系在反应初期形成的粒子会形成粒子堆,并随着聚合反应的继续,带有离子片段的自由基链段不断扩散进入粒子堆表面的小粒子,使其zeta电位不断增强,最终脱离粒子堆.提出了PEG水溶液中St/MMA无皂乳液共聚聚并脱析成核机理.
The effects of styrene (St) and methyl methacrylate (MMA) on the soap-free emulsion copolymerization of polyethylene glycol (PEG) were investigated by high power optical microscope, Coulter particle size analyzer, TEM and zeta potential tracking Particle size, particle size distribution and zeta potential changes.Polymer particle size will go from small to large (some even more than 1000μm in diameter, distributed in a very wide range of 0.04 ~ 2000μm) The number average distribution in the 0.04 ~ 0.18μm) process, and the particle size distribution from narrow to narrow, the final number-average particle size distribution concentrated in the narrow range of 0.04 ~ 0.18μm.Combined with the polymerization conversion data, according to the aqueous solution of PEG St / MMA soap-free emulsion copolymerization particle size changes, and zeta potential in the polymerization process is different from ordinary soap-free emulsion phenomenon, that the system formed particles in the initial reaction will form a particle stack, and with the polymerization continues, the band The free radical segments with ionic fragments diffused into the small particles on the surface of the particle stack to increase the zeta potential and finally get out of the particle stack. The St / MMA soap-free emulsion was copolymerized in the aqueous solution of PEG and the nucleation mechanism was analyzed.