摘要
引言
双水相体系主要用于蛋白质等高分子的分离纯化[1-5],近年来逐渐用于水溶性高分子的制备,发展成为一种新的聚合方法,即双水相聚合[6-12]。有效的相分离是双水相聚合正常进行的前提。Kim等[13]研究了聚乙二醇（PEG）/盐双水相体系的相分离,发现随PEG分子量增大,
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 transmittance declined suddenly,spectrophotometer was used 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 50.0 g was measured by the improved bromating method.The critical conversion was kept at about 37%～38% as the initiator amount increased from 0.005 g to 0.025 g and temperature increased from 45℃ to 65℃.The critical conversion decreased sharply as the monomers amount increased from 2.5 g to 12.5 g,decreased little with PEG amount increasing from 2.5 g to 12.5 g,and also decreased with PEG molecular weight increasing from 600 to 20000.But it increased with the mole fraction of DMC increasing 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 decreased linearly in both cases.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 or 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 a little smaller,and the effects of initiator amount and temperature were the 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—0.025 g,temperature 45—65℃,overall monomers amount 5.0—12.5 g,PEG amount 7.5—12.5 g,PEG molecular weight 10000—20000,mole fraction of DMC 5%—10%,respectively.
出处
《化工学报》
EI
CAS
CSCD
北大核心
2012年第2期647-652,共6页
CIESC Journal
基金
国家自然科学基金(20776125,20876136)
教育部新世纪优秀人才支持计划项目(NCET-05-0512)
浙江省杰出青年基金(R4110199)~~
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
acrylamide
methacryloyloxyethyl trimethyl ammonium chloride
aqueous two-phase copolymerization
critical conversion
critical molecular weight
