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| “Living”/controlled radical polymerization of vinyl acetate |
ZHAN Xiao-li1, JIANG Bo1, YI Ling-min2, ZHANG Qing-hua1,
CHEN Bi1, CHEN Feng-qiu1 |
1. Department of Chemical and Biochemical Engineering, Zhejiang University, Hangzhou 310027, China;
2. Key Laboratory of Advanced Textile Materials and Manufacturing Technology of Ministry of Education,
Zhejiang Science Technology University, Hangzhou 310018, China |
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Abstract The reversible addition fragmentation chain transfer radical polymerization (RAFT) of vinyl acetate (VAc) were conducted in ethyl acetate using four xanthates with different Z group as the chain transfer agents. Results showed that the chemical structure of xanthate, the ratio of xanthate to initiator, and the monomer mass fraction had prominent effect on the RAFT radical polymerization of VAc. When Z group of the xanthates was 4methoxyphenoxy, the RAFT polymerization of VAc was completely inhibited in presence of ethyl acetate in 720 minutes. The reason may be that the living center is stablized by the electronic transfer complex between VAc living chain end and the aromatic group in end of polymer. When Z groups of the xanthates were methoxy, ethoxy, or isopropoxy, the RAFT radical polymerization of VAc can proceed in a “living”/controlled way. The numberaverage relative molecular mass of polyvinyl acetate (PVAc) increased linearly with the conversion, and the relative molecular mass distribution index of PVAc was lower than 1.4.
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Published: 19 March 2012
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醋酸乙烯酯“活性”/可控自由基聚合
以4种不同Z基团结构的黄原酸酯为链转移剂,在乙酸乙酯中进行醋酸乙烯酯(VAc)的可逆加成断裂链转移自由基聚合.结果表明,黄原酸酯的化学结构、黄原酸酯与引发剂的量比、单体质量分数等因素对聚合有显著影响.当Z基团为4甲氧基酚基时聚合在720 min内完全阻聚,这可能是由于VAc增长自由基与自身或者其他聚合物链段中黄原酸酯的苯环形成电子转移络合物而造成活性中心稳定所致；当黄原酸酯的Z基团分别为甲氧基、乙氧基、异丙氧基时,可顺利实现VAc的可控自由基聚合,聚醋酸乙烯酯（PVAc）的数均相对分子质量随转化率线性增加,聚合物相对分子质量分布指数小于1.4.
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