Thermosensitive Random Copolymers of Hydrophilic and Hydrophobic Monomers Obtained by Living Cationic Copolymerization1
Thermosensitive Random Copolymers of Hydrophilic and Hydrophobic Monomers Obtained by Living Cationic Copolymerization1
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DOI：
10.1021/ma034730d
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发表时间：
2004-02
期刊：
影响因子：
5.5
通讯作者：
S. Sugihara;S. Kanaoka;S. Aoshima
中科院分区：
文献类型：
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作者：
S. Sugihara;S. Kanaoka;S. Aoshima
通过活性阳离子共聚反应合成了亲水性和疏水性单体的温敏性无规共聚物。在阳离子引发剂/Et1.5AlCl1.5引发体系下，异丁基乙烯基醚(IBVE)和2-(叔丁基二甲基硅氧基)乙基乙烯基醚(BMSiVE)在外加碱存在下发生共聚反应，得到了分子量分布较窄的共聚物。用Fineman−Ross方法测定了产物的相对反应性，结果表明产物具有高度随机的序列分布。随后的脱硅反应得到了一种定义良好的两亲无规共聚物：疏水单元(IBVE)和亲水单元(2-羟乙基乙烯基醚：HOVE)。加热时，产物无规共聚物的水溶液在临界温度下经历热诱导相分离。这种相分离在加热和冷却时是非常敏感和可逆的。序列分布的随机性是实现这种高度敏感性所不可缺少的。
Thermosensitive random copolymers of hydrophilic and hydrophobic monomers are synthesized via living cationic copolymerization. The synthesis starts with the copolymerization of isobutyl vinyl ether (IBVE) and 2-(tert-butyldimethylsilyloxy)ethyl vinyl ether (BMSiVE) using the cationogen/Et1.5AlCl1.5 initiating system in the presence of an added base to give a copolymer with a narrow molecular weight distribution. The relative reactivities determined by the Fineman−Ross method indicate that the product copolymer has a highly random sequence distribution. Subsequent desilylation gave a well-defined amphiphilic random copolymer of hydrophobic (IBVE) and hydrophilic units (2-hydroxyethyl vinyl ether: HOVE). On heating, an aqueous solution of the product random copolymer undergoes thermally induced phase separation at a critical temperature. This phase separation is quite sensitive and reversible on heating and cooling. The randomness of the sequence distribution is indispensable to realizing such highly sens...