通过自缩合乙烯基氧阴离子聚合制备超支化聚甲基丙烯酸羟丙酯

由甲基丙烯酸羟丙酯通过自缩合乙烯基氧阴离子聚合(self-condensing vinyl oxyanionic polymerization)制备了端羟基的超支化聚甲基丙烯酸酯. 以氢化钾(KH)和冠醚的复合物为引发剂时, 可以得到高分子量的聚合物. 用¹H NMR和¹³C NMR谱图证实了聚合物的超支化结构. 由于在聚合过程中存在质子转移反应, 引发剂与单体的摩尔比会影响所得聚合物的结构. 超支化聚合物的玻璃化转变温度在58.1～81.4 ℃之间, 且随着引发剂与单体的比例的减小而降低. 当引发剂与单体等摩尔比时, 所得聚合物的支化度为0.49.

Synthesis of Hyperbranched Poly(2-hydroxypropyl methacrylate) by Self-condensing Vinyl Oxyanionic Polymerization

Hyperbranched polymethacrylates with hydroxyl end groups were prepared by means of self-condensing vinyl oxyanionic polymerization of commercially available monomer 2-hydroxypropyl methacrylate. The hyperbranched polymers with high molecular weight were obtained with the complex of potassium hydride and 18-crown-6 as the initiator. The molecular structure of the hyperbranched polymers was confirmed with ¹H and ¹³C NMR spectra. The amount of initiator used in the polymerization could affect the structure of polymer based on a proton-transfer process. The glass transition temperature of the prepared polymers ranged from 58.1 to 81.4 ℃, and decreased with decreasing the initiator to monomer ratio. When the ratio of initiator to monomer equaled 1, the degree of branching of the resulting polymer was calculated to be 0.49.