Thermoreversible high-temperature gelation of an ionic liquid with poly(benzyl methacrylate-b-methyl methacrylate-b-benzyl methacrylate) triblock copolymer
Thermoreversible high-temperature gelation of an ionic liquid with poly(benzyl methacrylate-b-methyl methacrylate-b-benzyl methacrylate) triblock copolymer
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DOI：
10.1039/c2sm25375e
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发表时间：
2012-07
期刊：
影响因子：
3.4
通讯作者：
Yuzo Kitazawa;T. Ueki;Kazuyuki Niitsuma;S. Imaizumi;T. Lodge;M. Watanabe
中科院分区：
文献类型：
--
作者：
Yuzo Kitazawa;T. Ueki;Kazuyuki Niitsuma;S. Imaizumi;T. Lodge;M. Watanabe
在本文中，我们描述了一种新型的热敏三嵌段共聚物在离子液体（IL），显示了低温溶胶-高温凝胶转变。采用原子转移自由基聚合（ATRP）方法，以双官能团引发剂为引发剂，合成了以聚甲基丙烯酸苄酯（BA）为末端A嵌段，聚甲基丙烯酸甲酯（MMA）为中间B嵌段的阿坝三嵌段共聚物（P（BnMA-B-MMA-B-BnMA），简称BMB）。PBnMA嵌段和PMMA嵌段的数均分子量估计分别为25 kDa和33 kDa。从动态光散射获得的流体动力学半径的温度依赖性表明，在稀溶液（0.1重量%）中，三嵌段共聚物在常见的疏水IL，1-乙基-3-甲基咪唑鎓双（三氟甲磺酰基）酰胺（[C2mim][NTf 2]）中在135 °C左右表现出较低的临界胶束化温度（LCMT）型聚集行为。在[C2mim][NTf 2]中的20重量% BMB溶液的动态粘弹性测量证实，在加热至高于PBnMA末端嵌段的聚集温度时，在低温下为粘性液体（G′（储能弹性模量）G ″）。当三嵌段共聚物浓度低于10重量%时，没有观察到凝胶化。此外，热可逆离子凝胶表现出优异的溶胶-凝胶转变可逆性的多个加热/冷却循环进行了几天。
In this paper, we describe a novel thermosensitive triblock copolymer in an ionic liquid (IL) that shows a low-temperature-sol–high-temperature-gel transition. A well-defined ABA triblock copolymer consisting of poly(benzyl methacrylate) as the terminal A blocks and poly(methyl methacrylate) as the middle B block (P(BnMA-b-MMA-b-BnMA), BMB) was successfully synthesized using atom transfer radical polymerization (ATRP) from a bifunctional initiator. The number-average molecular weights of the PBnMA blocks and the PMMA block were estimated to be 25 kDa and 33 kDa, respectively. The temperature dependence of the hydrodynamic radius obtained from dynamic light scattering showed that in dilute solutions (0.1 wt%) the triblock copolymer exhibited lower critical micellization temperature (LCMT)-type aggregation behaviour around 135 °C in a common hydrophobic IL, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide ([C2mim][NTf2]). Dynamic viscoelastic measurements for a 20 wt% BMB solution in [C2mim][NTf2] confirmed that a viscous liquid at low temperature (G′ (storage elastic modulus) G′′) upon heating above the aggregation temperature of the PBnMA terminal blocks. No gelation was observed when the triblock copolymer concentration was below 10 wt%. Furthermore, the thermoreversible ion gel exhibited excellent sol–gel transition reversibility for multiple heating/cooling cycles performed over several days.