机构地区: 中山大学化学与化学工程学院
出 处: 《中山大学学报(自然科学版)》 2007年第4期50-54,共5页
摘 要: 以新合成的1-甲氧羰基-乙基-苄基二硫代乙酯(MEPD)作为RAFT试剂,在70℃下进行了β-蒎烯与丙烯酸甲酯的RAFT自由基共聚合研究。结果表明,在较低β-蒎烯投料比下(fβ-pinene=0.1),该共聚反应显示一级动力学特征,产物相对分子质量随单体总转化率增加而增加,相对分子质量分布较窄,表现出活性/可控聚合特征。但在较高β-蒎烯投料配比(fβ-pinene=0.2或0.3)的共聚体系中,随着单体转化率增加产物相对分子质量出现不增反降的反常现象,而且单体投料中β-蒎烯含量越高,该行为越明显。该文对该现象提出了相应的降解(链断裂)机理,1HNMR分析结果支持了该机理。 The controlled copolymerization of β-pinene and MA was carried out via the reversible addition-fragmentation transfer(RAFT) technique in bulk at 70 ℃.The copolymerization(fβ-pinene=0.1) using 1-methoxycarbonyl ethyl phenyldithioacetate(MEPD) as a RAFT agent exhibits "living"/controlled nature evidenced by the first-order polymerization kinetics,the linear increase in molecular weight with the overall conversion and the narrow molecular weight distribution.However,the molecular weights were found to decrease with conversion at higher β-pinene content(fβ-pinene=0.2 or 0.3) in the feed during the RAFT copolymerization.And a new mechanism of degradation was proposed for this "abnormal" behavior.