Design of Hydroxy-Functionalized Thermoresponsive Copolymers: Improved Direct Radical Polymerization of Hydroxy-Functional Vinyl Ethers
Design of Hydroxy-Functionalized Thermoresponsive Copolymers: Improved Direct Radical Polymerization of Hydroxy-Functional Vinyl Ethers
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DOI：
10.1021/acs.macromol.7b02084
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发表时间：
2017-11-14
期刊：
影响因子：
5.5
通讯作者：
Maeda, Yasushi
中科院分区：
文献类型：
--
作者：
Sugihara, Shinji;Yoshida, Ayano;Maeda, Yasushi
介绍了羟基官能团乙烯醚（OH-VE）共聚物在较低临界溶解温度（LCST）条件下的改进合成方法及其水溶液性能。采用自由基聚合直接制备了一系列OH-VE共聚物。研究了水和单体对2-羟乙基乙烯醚（HEVE）自由基聚合反应的影响。在40-60 wt %的水中，HEVE的自由基聚合进行了完全的单体转化。HEVE与其他乙烯醚（VEs）或醋酸乙烯（VAc）的共聚也进行得很顺利。在每种情况下，自由基共聚成功的主要关键是在悬垂或非酸性水作为溶剂中VE氧和羟基之间适当的氢键。特别是，OH-VE和不含羟基的VE的共聚是通过氢键单体配合物实现的。利用所得共聚物，我们证明了水溶性共聚物存在热响应行为。通过选择合适的共聚物组成，即组成或侧链中适当的亲疏水平衡，在水中观察到lcst型热响应行为。产物共聚物包括聚（HEVE-co-VAc）、碱水解聚（heve -co-乙烯醇）、聚（二乙二醇单乙烯基醚-co- vac）、聚（HEVE-co-VE） EVE: 2-甲氧基乙基乙烯醚、异丁基乙烯醚、正丁基乙烯醚和4-羟基丁基乙烯醚（HBVE）)和聚（HBVE-co- vac）。这些直接自由基共聚允许设计各种热响应羟基功能聚合物，具有可忽略的细胞毒性和可调的LCST。
The improved synthesis and aqueous solution properties of hydroxy-functional vinyl ether (OH-VE) copolymers with lower critical solution temperatures (LCST) in water are presented. A series of OH-VE copolymers were directly prepared by free radical polymerization. Effects of water and comonomers on the free radical polymerization using 2-hydroxyethyl vinyl ether (HEVE) were investigated in detail. The free radical polymerization of HEVE at 40-60 wt % in water proceeded with complete monomer conversion. The copolymerizations of HEVE with other vinyl ethers (VEs) or vinyl acetate (VAc) also proceeded smoothly. In each case, the primary key to success in the free radical copolymerization is proper hydrogen bonding between the VE oxygen and hydroxyl group in the pendant or nonacidic water as a solvent. In particular, the copolymerization of OH-VE and VE without a hydroxy group is enabled by a hydrogen-bonded monomer complex. Using the resulting copolymers, we demonstrated the existence of thermoresponsive behavior for the water-soluble copolymers. By choosing appropriate compositions for the copolymers, i.e., an appropriate hydrophilic/hydrophobic balance in the composition or in the side chain, LCST-type thermoresponsive behavior was observed in water. The product copolymers include poly(HEVE-co-VAc), the alkali hydrolyzed poly(HEVE-co-vinyl alcohol), poly(diethylene glycol monovinyl ether-co-VAc), poly(HEVE-co-VE) EVE: 2-methoxyethyl vinyl ether, isobutyl vinyl ether, n-butyl vinyl ether, and 4-hydroxybutyl vinyl ether (HBVE)], and poly(HBVE-co-VAc). These direct radical copolymerizations allow the design of various thermoresponsive hydroxy-functional polymers with negligible cytotoxicity and tunable LCST.