丙烯酸甲酯三元复合乳化剂微乳液聚合

MA MINIEMULSION POLYMERIZATION IN THREE-ELEMENT COMPLEX EMULSIFIER

在十二烷基硫酸钠(SDS)、平平加OS—15(OS)和十六醇(HDL)三元复合乳化剂中,用(NH_4)_2S_2O_8/NaHSO_3氧化—还原引发体系引发的MA(丙烯酸甲酯)微乳液聚合研究发现:在温度15℃、(NH_4)_2S_2O_4与NaHSO_3摩尔浓度比为3:2左右时,反应速率最大,在一定反应时间和引发剂用量条件下,采用程序升温和半连续滴加引发剂有利于提高最终转化率;通过对聚合前乳液单体液滴直径的光学显微照片和聚合后乳胶粒子的透射电镜照片(TEM)的比较,初步认为加入HDL的三元复合乳化剂的乳液聚合属于以单体液滴引发聚合成核为主的微乳液聚合。

MA(methyl acrylate) miniemulsion polymerization was studied in SLS(Sodium Lauryl sulfate) OS-15 and HDL(Hoxadecanol)three-element complex-emulsifier,applying (NH4)2S2O8-NaH-SO3 Oxidation- reduction initiator. The effects of surfactant and cosurfactant concentration, method added (NH4)2S2O8 and NaHSO3, Polymerization temperature on both kinetic and latex stability were studied. When the molar concentration ratio of (NH4)2S2O8 and NaHSO3 is about 3/2,Polymerization rate at 15°C is the highest. If total polymerization time and intiator concentration are unchanged, program increase temperature and dropping semicontinously initiator are adantageous to total conversion of polymerization. By measuring and comparing optical micrographs of monomer droplet size before polymerization and tranmission electron micrographs (TEM)of latexes, We reason that the emulsion polymerization in above three-element complex emulsifier is miniemulsion polymerzation in which the principal locus for initiation of polymerization is the droplets.