Iodine transfer radical polymerization of vinyl acetate in fluoroalcohols for simultaneous control of molecular weight, stereospecificity, and regiospecificity
Iodine transfer radical polymerization of vinyl acetate in fluoroalcohols for simultaneous control of molecular weight, stereospecificity, and regiospecificity
复制标题
DOI：
10.1021/ma0602775
复制
发表时间：
2006-05
期刊：
影响因子：
5.5
通讯作者：
Kazuhiko Koumura;K. Satoh;M. Kamigaito;Y. Okamoto
中科院分区：
文献类型：
--
作者：
Kazuhiko Koumura;K. Satoh;M. Kamigaito;Y. Okamoto
本文首次报道了在醋酸乙烯酯（VAc）自由基聚合过程中同时控制聚醋酸乙烯酯的立构规整度和分子量。采用一系列氟醇[（CF_3）_3COH，（CF_3）_2CHOH，PhC（CF_3）_2 OH，m-C_6 H_4 {C（CF_3）_2 OH}_2]作为醋酸乙烯酯碘转移自由基聚合的溶剂，聚合物的分子量由单体与转移剂的比例决定，聚合物的立构规整度由溶剂控制。在氟代醇中，使用氟代二醇m-C6 H4 {C（CF 3）2 OH}2不仅导致更高的间同立构规整度（r ≤ 60%），而且还改善了分子量控制，导致在CH 2 I（CO2 Et）和偶氮引发剂[2，2 '-偶氮双（4-甲氧基-2，4-二甲基戊腈）]存在下在20 °C下窄的分子量分布（MWD）（Mw/Mn ≤ 1.20）。用相同的体系可得到相对分子质量分布较窄（Mw/Mn < 1.6）的高分子量聚合物（Mn > 7 × 104）。头对头联系的内容是...
The simultaneous control of the tacticity and molecular weight of poly(vinyl acetate) during the radical polymerization of vinyl acetate (VAc) is reported for the first time. A series of fluoroalcohols [(CF3)3COH, (CF3)2CHOH, PhC(CF3)2OH, m-C6H4{C(CF3)2OH}2] were employed as solvents for the iodine transfer radical polymerization of VAc, in which the molecular weight of the resultant polymer was determined by the monomer-to-transfer agent ratio and its tacticity was controlled by the solvent. Among the fluoroalcohols, the use of fluorodiol, m-C6H4{C(CF3)2OH}2, not only led to a higher syndiotacticity (r ∼ 60%) but also improved the molecular weight control, resulting in narrow molecular weight distributions (MWD) (Mw/Mn ∼ 1.20) in the presence of CH2I(CO2Et) and an azo-initiator [2,2‘-azobis(4-methoxy-2,4-dimethylvaleronitrile)] at 20 °C. High molecular weight polymers (Mn > 7 × 104) with a relatively narrow MWD (Mw/Mn < 1.6) were obtained with the same system. The content of the head-to-head linkages was...