Microphase-separated structures of ion gels consisting of ABA-type block copolymers and an ionic liquid: A key to escape from the trade-off between mechanical and transport properties
Microphase-separated structures of ion gels consisting of ABA-type block copolymers and an ionic liquid: A key to escape from the trade-off between mechanical and transport properties
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DOI：
10.1016/j.polymer.2020.122849
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发表时间：
2020-10-07
期刊：
影响因子：
4.6
通讯作者：
Watanabe, Masayoshi
中科院分区：
文献类型：
--
作者：
Mizuno, Haruna;Hashimoto, Kei;Watanabe, Masayoshi
当离子液体(IL)与两亲性ABA型三嵌段共聚物结合时，不溶的A嵌段聚集形成机械骨架，而可溶的B嵌段通过结合IL形成离子传输路径。因此，可以获得具有离子液体的高离子导电性的自立式离子凝胶。在这项研究中，我们研究了嵌段共聚物形成的微结构(球形、圆柱形、回旋体和片状结构)对离子凝胶的离子导电性和力学性能的影响。结果，通过热致有序-有序转变，成功地获得了形成各向同性双连续结构的离子凝胶。具有双连续结构的离子凝胶具有良好的力学性能(储能模数，G‘接近1.0 Mpa)和良好的离子导电性(sigma类似于0.1ms cm(-1))。相反，具有各向异性结构(圆柱形结构)的离子凝胶具有较弱的力学性能和较低的离子导电性。双连续结构的特性可能是解决电化学装置用电解液材料力学性能和传输性能之间权衡的关键。
Upon combination of an ionic liquid (IL) with an amphiphilic ABA-type triblock copolymer, the insoluble A blocks aggregate to form mechanical frameworks and the soluble B blocks form ion-transport paths by incorporating the IL. Consequently, a self-standing ion gel, exhibiting the characteristic high ionic conductivity of ILs, can be obtained. In this study, we investigated the effect of microstructures formed by the block copolymer (spherical, cylindrical, gyroid, and lamellar structures) on the ionic conductivity and mechanical properties of the ion gel by focusing on the microstructures. As a result, an ion gel that formed an isotropic bicontinuous structure was successfully obtained via a heat-induced order-order transition. The structure was maintained even at room temperature, and the ion gel having a bicontinuous structure exhibited favorable mechanical properties (storage modulus, G' similar to 1.0 MPa) and good ionic conductivity (sigma similar to 0.1 mS cm(-1)). In contrast, the ion gels having anisotropic structures (cylindrical structure) exhibited weaker mechanical properties and lower ionic conductivity. The characteristics of bicontinuous structures may be the key to resolving the trade-off between mechanical and transport properties of electrolyte materials for electrochemical devices.