Radical transfer on styrenic macromonomers of polyoxyethylene—II. Studies on model compounds
Radical transfer on styrenic macromonomers of polyoxyethylene—II. Studies on model compounds
复制标题
聚氧乙烯苯乙烯类大单体的自由基转移——模型化合物的研究。
DOI：
10.1016/0014-3057(87)90123-6
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发表时间：
1987
影响因子：
6
通讯作者：
A. Guyot
中科院分区：
文献类型：
--
作者：
T. Hamaide;A. Revillon;A. Guyot
在先前对丙烯酸丁酯与苯乙烯类大分子单体共聚的研究中，表明苄基氢原子参与了转移过程。为了研究后一反应，合成了模型化合物并用作丙烯酸丁酯聚合中的转移剂。对于未取代的苄基醚，即具有两个苄基氢原子，转移常数估计约为 0.0021；动力学研究表明，再引发效率约为80%。甲基取代苄基氢原子导致转移过程无需重新引发。测得的转移常数为0.0018。使用 Jenkins 和 Kice 方程计算传播和转移自由基的浓度。对于未取代的醚，这些方法不符合我们的动力学数据。将转移剂掺入聚合物中后进行 GPC，u.v.和核磁共振波谱。似乎一些聚合物链可能包含多于一个的转移剂单元，尽管统计计数显示每个聚合物链的转移剂单元的平均数量小于一个，即使具有高的再引发效率。
In a previous study of the copolymerization of butyl acrylate with styrenic macromonomers, it was shown that benzylic hydrogen atoms are involved in a transfer process. In order to investigate these latter reaction, model compounds were synthesized and used as transfer agents in the polymerization of butyl acrylate. For a non-substituted benzylic ether, i.e. having two benzylic hydrogen atoms, the transfer constant was estimated to be around 0.0021; kinetic studies showed that the efficiency of reinitiation is about 80%. Replacement of a benzylic hydrogen atom by a methyl group led to a transfer process with no reinitiation. The measured transfer constant was 0.0018. The concentrations of the propagating and transferring radicals were calculated using the Jenkins and Kice equations. For the non-substituted ether, these methods did not fit our kinetic data. The incorporation of the transfer agents in the polymer was followed by GPC, u.v. and NMR spectroscopies. It appears that some polymer chains may include more than one transfer agent unit, though a statistic counting has shown the average number of transfer agent units per polymer chain to be less than one, even with a high reinitiation efficiency.