关键词: 丙烯酰胺, 甲基丙烯酰氧乙基三甲基氯化铵, 双水相共聚, 临界转化率, 临界分子量

Abstract: The aqueous two-phase copolymerization of acrylamide(AM) and methacryloyloxyethyl trimethyl ammonium chloride(DMC) with the initiator 2,2’-azobis[2-(2-imidazolin-2-yl)propane]-dihydrochloride in aqueous poly(ethylene glycol)(PEG) solution was studied. In order to determine the phase separation point where the transmittance declined suddenly, the spectrophotometer was employed to detect the transmittance of the reaction solution on-line. The effect of various parameters on the critical conversion of the reaction solution with total mass 50.0g was measured by improved bromating method. The critical conversion kept at about 37~38% as the initiator amount increased from 0.005g to 0.025g and the temperature increased from 45℃ to 65℃. And it decreased sharply as the monomers amount increased from 2.5g to 12.5g, decreased little with PEG amount increased from 2.5g to 12.5g, and also decreased with PEG molecular weight increased from 600 to 20000. But it increased with the mole fraction of DMC increased from zero to 20%. The critical molecular weight was also investigated by gel permeation chromatogram(GPC). When the initiator amount increased or temperature rose, the critical molecular weight both decreased linearly. When the overall monomers amount or PEG amount increased, the critical molecular weight increased firstly, and then decreased. The highest critical molecular weight was 3.64×105 and 7.59×105, respectively. As the mole fraction of DMC increased, the critical molecular weight decreased linearly. But when PEG molecular weight increased, it increased accordingly. The results showed that the effects of PEG molecular weight and mole fraction of DMC were most remarkable, the effects of overall monomers amount and PEG amount were little smaller, and the effects of initiator amount and temperature were smallest. Therefore, in order to bring about effective phase separation of the aqueous two-phase copolymerization system, the reaction parameters should be controlled in the suitable range. That is, initiator amount 0.005~0.025g, temperature 45~65℃, overall monomers amount 5.0~12.5g, PEG amount 7.5~12.5g, PEG molecular weight 10000~20000, mole fraction of DMC 5~10%, respectively.

Key words: acrylamide;methacryloyloxyethyl trimethyl ammonium chloride;aqueous twophase copolymerization;critical conversion, critical molecular weight