关键词: 滴径, 共聚物组成, 成滴机理

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