星状支化PS的合成与表征

利用原子转移自由基聚合方法,以α-溴代苯乙烷为引发剂,CuBr／2,2'-联二吡啶作为催化体系,合成星状支化聚苯乙烯(PS)。引发二苯甲烷双马来酰亚胺／苯乙烯电荷转移络合物体系就地优先生成多官能团引发剂,再引发苯乙烯聚合。采用核磁共振、凝胶渗透色谱、多角度激光散射和特性黏数等分析方法对聚合过程、聚合物结构、聚合物相对分子质量及其分布进行分析与表征。由多角度激光散射法测定的绝对重均分子量是由凝胶渗透色谱测定的4倍左右,相同相对分子质量的线型PS的特性黏数是星状PS的20倍,证实聚合产物确实具有支化结构。

Synthesis and characterization of star-shaped polystyrene

Star-shaped polystyrene (PS) was synthesized with a multifunction initiator via atom transfer radical polymerization. The multifunction initiator was formed in-situ from the charge transfer complex system consisting of diphenylmethane bismaleimide and styrene, in the presence of 1-phenylethyl bromide as initiator and CuBr/2,2'-bipyridine as catalyst system. The polymerization process and structure, relative molecular mass and its distribution of the resultant polymer were analyzed and characterized by nuclear magnetic resonance spectroscopy, gel permeation chromatography(GPC),multi-angle laser light scattering spectrometry (MALLS), Fourier transform infrared spectroscopy and intrinsic viscosity analysis. The absolute weight average molecular mass determined by MALLS was 4 times of that obtained by GPC. The intrinsic viscosity of linear polystyrene with the same relative molecular mass was 20 times of the star-shaped polymer, thereby confirming the formation of branched structure in the polymer so prepared.