半连续RAFT反相乳液共聚合制备星型阳离子聚丙烯酰胺

Synthesis of Star Cationic Polyacrylamides Using the Copolymerization of Semi-bath Reversible Addition-Fragmentation Chain Transfer (RAFT) Inverse Emulsion

首次提出采用"臂先"方法的丙烯酰胺(AM)、甲基丙烯酰氧乙基三甲基氯化铵(DMC)及N,N’-亚甲基双丙烯酰胺(BisAM)的半连续RAFT反相乳液共聚合方法制备星型阳离子聚丙烯酰胺(sCPAM),该聚合物具有阳离子链段集中在含超支化聚丙烯酰胺(PAM)核的臂末端的结构。通过控制AM和BisAM的加料以及AM与RAFT链转移剂的比例,合成了不同臂长、超支化PAM核及臂末端阳离子组成的sCPAM。研究表明在使用BisAM与AM和DMC摩尔比为2～5:1600的低二烯类单体用量条件下,高效制备了臂数为2.5～6.9、星型聚合物含量高达92.9%的sCPAM。TiO2浊液絮凝研究表明提高星型结构含量以及臂末端阳离子密度的sCPAM具有更好的絮凝效果,絮凝性能优于具有更高阳离子度与分子量的线性无规阳离子聚丙烯酰胺工业絮凝剂C535M。

An ＂arm-first＂ semi-batch RAFT inverse emulsion copolymerization of acrylamide （AM）, [2-（methacryloyloxy）ethyl]trimethylammonlum chloride （DMC）, and N,N＇-methylenebisacrylamide （BisAM） was developed for the first time to synthesize the star cationic polyacrylamides （sCPAM） with cationic chain segments concentrating at the arm ends of the hyperbranched polyacrylamide （PAM） cores. The sCPAMs having various arm lengths, hyperbranched PAM cores, and chain-end cationic segment compositions were synthesized via controlling the AM and BisAM feeding and the molar ratio of AM to RAFT chain transfer agent The sCPAMs having the number of arms between 2.5 and 6.9 and up to 92.9%（wt） of star structures were successfully produced at a low usage of BisAM with the molar ratios of BisAM to AM and DMC of 2-5 to 1600. The flocculation test with TiO2 particles shows that the sCPAMs comprising larger fraction of star polymer and having high terminal cationic monomer density possess better flocculation performance. The performance of the sCPAM sample was superior to that of the commercial linear cationic PAM sample C535M which has higher cationic density and higher molecular weight.