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本文用二种双官能团引发剂进行基团转移嵌段共聚研究,得到了一系列实测分子量和理论分子量相近、分子量分布较窄的A-B-A型嵌段共聚物。用GPC、~1H-NMR、DSC等手段对嵌段共聚物进行了表征,证明确是两相嵌段共聚丙烯酸酯。发现位阻较大的单体作为第二单体时不利于聚合。过高的催化剂用量使嵌段共聚的总转化率降低。使用极性较大的溶剂可缩短第一步聚合的诱导期,但不影响第二步聚合的诱导期,即极性较大的溶剂有利于催化剂的离解。单体浓度增大使共聚物的分子量减小,多分散性指数增大。可通过单体投料比改变共聚物的热形变温度。
In this paper, two kinds of bifunctional initiators were used for group transfer block copolymerization. A series of A-B-A block copolymers with similar molecular weight and theoretical molecular weight and narrow molecular weight distribution were obtained. The block copolymer was characterized by GPC, ~ 1H-NMR and DSC, which proved that the two-phase block copolymerized acrylate was indeed. It was found that monomers with larger steric hindrance were not conducive to polymerization as the second monomer. Too high catalyst loading reduces the overall conversion of block copolymerization. The use of more polar solvents shortens the induction period of the first polymerization but does not affect the induction period of the second polymerization. That is, the more polar solvent facilitates the dissociation of the catalyst. Increasing the monomer concentration reduces the molecular weight of the copolymer and the polydispersity index increases. The thermal deformation temperature of the copolymer can be varied by the monomer charge ratio.