A Zwitterionic ABC triblock copolymer that forms a "Trinity" of micellar aggregates in aqueous solution
A Zwitterionic ABC triblock copolymer that forms a "Trinity" of micellar aggregates in aqueous solution
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DOI：
10.1021/ma048789b
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发表时间：
2004-09-21
期刊：
影响因子：
5.5
通讯作者：
Armes, SP
中科院分区：
文献类型：
--
作者：
Cai, YL;Armes, SP
使用基于PEO的大分子引发剂首先聚合甲基丙烯酸2-(二乙氨基)乙酯(DEA)，然后通过ATRP在20℃的甲醇中一锅合成聚合甲基丙烯酸2-羟乙酯(HEMA)。通过在温和条件下使用过量的琥珀酸酐在吡啶中酯化HEMA嵌段上的羟基，将所得的PEO-PDEA-PHEMA三嵌段共聚物前体成功转化为相应的PEO-PDEA-PSEMA两性离子三嵌段共聚物。只需在环境温度下调节溶液的 pH 值，这些 PEO-PDEA-PSEMA 三嵌段共聚物就可以在水溶液中形成“三位一体”的胶束聚集体。形成这三种类型胶束的驱动力分别是氢键、聚电解质间络合和疏水相互作用。在低pH值下形成的氢键PSEMA/PEO核心胶束在较高温度下或通过添加甲醇被破坏，形成PSEMA核心聚集体。在 IEP 周围形成的 PSEMA/PDEA 聚电解质胶束对水溶液的离子强度非常敏感。这些溶液的稀释导致胶束膨胀，并最终发生解离。据我们所知，这种新型ABC三嵌段共聚物的丰富的水溶液行为是前所未有的，因为这是第一次通过单组分系统在水溶液中形成三种类型的胶束。
A PEO-based macroinitiator was used to first polymerize 2-(diethylamino)ethyl methacrylate (DEA) and then 2-hydroxyethyl methacrylate (HEMA) in a one-pot synthesis via ATRP in methanol at 20 degreesC. The resulting PEO-PDEA-PHEMA triblock copolymer precursors were successfully converted into the corresponding PEO-PDEA-PSEMA zwitterionic triblock copolymers by esterification of the hydroxy groups on the HEMA block using excess succinic anhydride in pyridine under mild conditions. A "trinity" of micellar aggregates was formed by these PEO-PDEA-PSEMA triblock copolymers in aqueous solution simply by adjusting the solution pH at ambient temperature. The driving forces for forming these three types of micelles were hydrogen-bonding, interpolyelectrolyte complexation, and hydrophobic interactions, respectively. The hydrogen-bonded PSEMA/PEO-core micelles that were formed at low pH were disrupted at higher temperatures or by addition of methanol, leading to PSEMA-core aggregates. The PSEMA/PDEA interpolyelectrolyte micelles formed at around the IEP were very sensitive to the ionic strength of the aqueous solution. Dilution of these solutions resulted in swollen micelles, and eventually dissociation occurred. As far as we are aware, the rich aqueous solution behavior of this new class of ABC triblock copolymers is unprecedented since, for the first time, three types of micelles are formed in aqueous solution by a single-component system.