丙烯酰胺/丙烯酸/甲基丙烯酸甲酯双水相共聚过程的成滴机理

Droplet formation mechanism of acrylamide/acrylic acid/methyl methacrylate aqueous two-phase copolymerization

引言近年来,采用双水相共聚合反应技术制备聚丙烯酰胺（PAM）备受关注[1-4]。相比于均聚法,使用共聚法合成阴离子型聚丙烯酰胺（APAM）无后水解工艺,生产周期较短,尤其是由丙烯氧化生产丙烯酸（AA）的成本比丙烯酰胺（AM）低很多,因此使用AM与AA共聚的方法生产APAM具有明显优势[5]。另外,前期实验已证明,

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 aqueous two-phase copolymerization.By using dynamic light scattering（DLS）,the droplet appearance and growth in the initial stage of the aqueous two-phase copolymerization was on-line detected,and the results showed that the copolymer droplet aggregated 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 proceeded.By using gas chromatography,the exact monomer residues were detected and the composition of the copolymer chain was calculated.The reaction could 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 grew 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.