含芳酰胺结构的新型甲壳型液晶高分子PMPACS的聚合反应动力学研究

采用称量法和GPC,研究了以二甲基乙酰胺为溶剂,偶氮二异丁腈为引发剂,自由基溶液聚合制备含芳酰胺结构的新型甲壳型液晶高分子聚乙烯基对苯二甲酸二(4-甲氧基苯胺)](PMPACS)的聚合反应动力学.研究发现,(1)MPACS的聚合反应在60℃时主要为双基偶合终止,所以反应后期聚合物分子量明显增大,分子量分布变窄;(2)该反应的聚合反应速率方程为Rp=kpM]I]1/2,表观活化能Eα=44 kJ/mol,在60℃时的聚合反应常数kp=1.04 L·mol-1·h-1;(3)相同聚合条件下,单体的转化率和数均分子量随单体初始浓度M]0的增加而增大,当引发剂浓度I]0增加时,聚合物的分子量随之降低,分子量分布增大;(4)该研究虽采用普通自由基聚合,所得聚合物的分子量分布却较窄,仅为1.1～1.4.

POLYMERIZATION KINETICS OF A NEW KIND OF MESOGEN-JACKETED LIQUILD CRYSTAL POLYMER PMPACS WITH MESOGENS OF ACROMATIC AMIDE STRUCTURE

A new kind of mesogen-jacketed liquid crystalline polymer with mesogens of acromatic amide structure,poly{2,5-bis-(4-methoxyphenyl) aminocarbonyl] styrene}(PMPACS),was successfully synthesized through traditional radical polymerization.Dimethylacetamide(DMAc) was used as solvent and azobisisobutyronitrile(AIBN) was used as initiator in this polymerization.The kinetics of the polymerization was investigated by weighing method and gel permeation chromatography(GPC).The results indicated:(1) The polymerization was mainly ended by biradical coupling termination when the reaction temperature was 60 ℃.Therefore,the molecular weight of PMPACS increased and its distribution decreased during the later period.(2) The polymerization rate equation could be written as Rp=kp1/2.The overall activation energy of polymerization reaction was 44 kJ/mol.And the rate constant of polymerization reaction was 1.04 L·mol-1·h-1 at 60 ℃.(3) The conversion and the number-average molecular weight both increased as the initial monomer concentration increased.The number-average molecular weight decreased as the initiator concentration increased.(4) The molecular weight distribution of PMPACS decreased as the concentration of AIBN was narrow although the traditional radical polymerization was used.