Abstract: Acrylamide (AM)/acrylic acid (AA)/methyl methacrylate (MMA) copolymer with the stabilizer poly(acrylic acid sodium) (PAANa) dispersed in the ammonium sulfate (AS) solution was prepared through the aqueous two-phase copolymerization. By using the dynamic light scattering (DLS), the droplet appearance and growth in the initial stage of the aqueous two-phase copolymerization was on-line detected, and results showed that the copolymer droplet aggregates with each other at the initial stage. Therefore, the droplet size distribution became wide at first, and then turned to narrow again as the copolymerization proceeds. By using the gas chromatography, the exact monomer residues were detected and the composition of the copolymer chain was calculated. The reaction can be divided into three stages. The AM and MMA segments were the main part of the copolymer chain at the first stage, at the second stage AM grows mainly into the copolymer chain, and the AA and AM segments were the main part of the copolymer chain at the third stage. Eventually, the droplet formation mechanism of the aqueous two-phase copolymerization of AM/AA/MMA with the stabilizer PAANa in AS aqueous solution was presented. The negative charge of the AA segment in the copolymer chain was considered as a significant factor in the stabilization of the aqueous two-phase system.

Key words: droplet size, composition of copolymer chain, droplet formation mechanism

摘要： 在含聚丙烯酸钠（PAANa）的硫酸铵（AS）水溶液中，进行丙烯酰胺（AM）/丙烯酸（AA）/甲基丙烯酸甲酯（MMA）双水相共聚合反应，制备阴离子型聚丙烯酰胺水溶性聚合物分散液。采用动态激光光散射（DLS）在线检测了双水相聚合初期液滴形成及生长规律，发现液滴在反应初期存在聚并现象，滴径分布先变宽后变窄。采用气相色谱检测了共聚过程中各单体的残余量，推算聚合物链结构组成：反应前期聚合物链以AM和MMA链节为主，反应中期聚合物链以AM链节为主，反应后期聚合物链以AA和AM链节为主。提出了AM/AA/MMA双水相共聚过程的成滴机理，其中聚合物链上AA链节所带有的负电荷是聚合产物稳定分散、不易于凝聚的重要因素。

关键词: 滴径, 共聚物组成, 成滴机理