Controlled cationic polymerization of p-(chloromethyl)styrene:: BF3-catalyzed selective activation of a C-O terminal from alcohol
Controlled cationic polymerization of p-(chloromethyl)styrene:: BF3-catalyzed selective activation of a C-O terminal from alcohol
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DOI：
10.1021/ma0216876
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发表时间：
2003-05-20
期刊：
影响因子：
5.5
通讯作者：
Sawamoto, M
中科院分区：
文献类型：
--
作者：
Kamigaito, M;Nakashima, J;Sawamoto, M
以醇[CH_3CH（Ph）OH]为引发剂，高亲氧性刘易斯酸BF_3·OEt_2为活化剂/催化剂，实现了对氯甲基苯乙烯（CMS）的可控阳离子聚合。该聚合通过BF 3介导的醇的C-O键的选择性活化引发，并通过所得的类似于C-OH休眠聚合物末端的类似活化进行，以得到没有支化结构的线性聚合物，所述支化结构将通过氯甲基侧基的反应形成。加入少量的水延缓聚合反应，得到受控的分子量，随着转化率的增加，并接近活性聚合物的计算值。另外使用氢氧化四丁基铵（n-Bu 4 NOH）作为氢氧根阴离子源进一步使分子量分布变窄（M-w/M-n = 1.5-1.8）。CMS与苯乙烯或对氯苯乙烯与BF 3基体系的共聚也得到具有可控分子量的共聚物。这是CMS的受控阳离子聚合而没有氯甲基官能团的并发副反应的第一个实例。成功归因于使用高度亲氧的BF 3.OEt2与适当的醇引发剂结合。
Controlled cationic polymerization of p-(chloromethyl)styrene (CMS) was achieved with an alcohol [CH3CH(Ph)OH] as an initiator and a highly oxophilic Lewis acid, BF3.OEt2, as an activator/catalyst. The polymerization is initiated by the BF3-mediated selective activation of the C-O bond of the alcohol and proceeds via a similar activation of the resulting similar tosimilar toC-OH dormant polymer terminal to give linear polymers without branched structures that would form via reactions of the chloromethyl pendent groups. Addition of a small amount of water retarded the polymerization to give controlled molecular weights that increased with conversion and were close to the calculated values for living polymers. Additional use of tetrabutylammonium hydroxide (n-Bu4NOH) as a hydroxide anion source further narrowed the molecular weight distribution (M-w/M-n = 1.5-1.8). Copolymerization of CMS and styrene or p-chlorostyrene with the BF3-based system also gave copolymers with controlled molecular weights. This is the first example of controlled cationic polymerization of CMS without concurrent side reactions of the chloromethyl functional groups. The success owes to the use of highly oxophilic BF3.OEt2 in conjunction with an appropriate alcoholic initiator.