以2,2′-联吡啶与丙二腈为添加剂的苯乙烯活性自由基聚合的研究

研究了稳定自由基存在下苯乙烯的活性聚合 .发现在 2 ,2′ 联吡啶的存在下 ,苯乙烯聚合的分子量控制效果提高 ,分子量可控 ,分子量分布较窄 .在与丙二腈共同作用时 ,可在 4h内达到 85 %的转化率 ,分子量分布在 1 5以下 ,分子量控制误差在 2 0 %以下 .设计分子量在 1× 10 4 ～ 9× 10 4 的范围内 ,实测分子量和理论分子量相近 .

THE RESEARCH OF 2,2′-BIPYRIDINE AND MALONONITRILE AS ADDITIVES FOR STYRENE LIVING RADICAL POLYMERIZATION

The living free radical polymerization of styrene was studied with benzoyl peroxide as the initiator in the presence of TEMPO (2,2,6,6 tetramethylpiperidinyl 1 oxy).It was found that styrene polymerization was distinctly accelerated by means of using malononitrile (MN) as additive.The purpose of this paper is to explore the effect of MN/bpy on the control of molecular weight.These mixture additives were able to control the polymerization of styrene to high conversion (85%) in 4 hours, and samples of molecular weight from 1×10 4 to 9×10 4 and with polydispersities of 1.15 to 1.4 were readily obtained.In comparison with the polymerization without any additives,these systems represented a dramatic improvement in the ability to control the molecular weight.The molecular weight of the polymer gradually increased with time, while the narrow molecular weight distribution remained unchanged.The molecular weight evolved in a nearly linear fashion with increasing conversion.Using a 1∶1 2 molar mixture of BPO and TEMPO with [Bpy]/[TEMPO]=2/1,[MN]/[TEMPO]=2 5,the conversion of the polymerization at 135℃ reached 85% in 4 hours, and the polydispersity was below 1^5, and the difference between the theoretical molecular weight and the experimental molecular weight was controlled below 20%.