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研究了O2与CuBr2/配体络合物对苯乙烯（St）的热聚合,以及O2对CuBr/配体催化St的原子转移自由基聚合（A-TRP）的影响,采用气相色谱跟踪单体转化率、凝胶渗透色谱跟踪聚合物PSt分子量的变化。结果表明,在热聚合中,O2可显著提高聚合反应速率,而CuBr2/配体络合物则起到电荷转移型阻聚剂的作用;在ATRP中,O2显著降低聚合反应速率和引发效率。O2存在下的ATRP体系中低转化率下所得PSt的分子量呈双峰分布,分子量均随着转化率增加而上升,但在高转化率下高分子量峰无法检测到,而严格除氧后则只出现单峰。由此可见,在St的ATRP中,CuBr络合物可催化O2与St的热聚合,形成聚合物链。由于O2的低浓度,在一般ATRP体系中,此机理产生的PSt不超过全部聚合物链的1%。

The role of CuBr2/ligand in thermal polymerization and that of oxygen in CuBr/ligand-catalyzed atom transfer radical polymerization(ATRP) of styrene(St) were investigated.The results show that oxygen promotes the thermal polymerization but CuBr2/ligand inhibites it.In ATRP of St,oxygen would lower the reaction rate and the initiator efficiency.Gel permeation chromatography results suggest that the presence of O2 in ATRP of St would lead to the bi-modal molecular-weight distribution at early stage,the percentage of high-molecular weighy(MW) components decreases gradually with the conversion.It is suggested that the formation of high molecular weight PSt is attributed to the CuBr/ligand-catalyzed addition of oxygen to St.However,due to low concentration of oxygen,the percentage of so-formed PSt in a typical ATRP systems is below 1%.