4,5-二氢化-2-(8-十七碳烯基)-1H-咪唑-1-乙胺配合物催化苯乙烯反向原子转移自由基聚合

Reverse Atom Transfer Radical Polymerization of Styrene Catalyzed by CuCl_2-2-(8-Heptadecenyl)-4,5-Dihydro-1H-Imidazole-1-Ethylamine System

以叔丁基过氧化氢(TBHP)为引发剂,4,5-二氢化-2-(8-十七碳烯基)-1H-咪唑-1-乙胺(OLC)为配体,FeCl3,NiCl2,CuCl2分别为催化剂,实现了苯乙烯(St)进行反向原子转移自由基聚合(RATRP)反应合成聚苯乙烯(PSt)。实验结果表明,St的RATRP反应为活性可控反应,符合一级反应动力学;PSt的相对分子质量随St转化率的增加呈线性增加,PSt的相对分子质量分布较窄,表明RATRP反应为活性可控。在TBHP-CuCl2-OLC催化体系中,反应速率最快,PSt的相对分子质量分布最窄(1.29),引发效率最高(0.89);扩链反应也证实该RATRP反应具有活性可控的特征。在TBHP-CuCl2-OLC催化体系中,考察不同温度下的表观增长速率常数和自由基浓度,并求得St的RATRP反应的表观活化能(73.39kJ/mol)和平衡态焓(40.88kJ/mol)。

Reverse atom transfer radical polymerization （RATRP） of styrene （St） was investigated at 120 ℃ with ten-butyl hydroperoxide （TBHP） as initiator, 2-（ 8-heptadecenyl ）-4,5-dihydro-lH- imidazole-l-ethylamine（OLC） as ligand, and FeCl3, CuCl2 or NiCl2 as catalyst. The results indicated that the polymerization was well-controlled and accorded with first order reaction kinetics. The relative molecular mass of the resulted polystyrene increased with St conversion and its relative molecular mass distribution（Mw/Mn ） was narrow. For the TBHP-CuCl2-OLC catalystic system, the polymerization rate was the fastest with high initiation efficiency（f=0.89） and Mw/Mn was the narrowest（1.29）. The chain extension reaction revealed that the polymerization was based on RATRP. Apparent rate constant of the polymerization and free radical concentration all increased with rise of temperature. Apparent activation energy and equilibrium enthalpy of the RATRP were 73. 39 kJ/mol and 40. 88 kJ/mol, respectively.