Ishikawa Asumi, Ikeda Namie, Maeda Shuichi, Fujii Kenta
Graduate School of Sciences and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611, Japan.
Phys Chem Chem Phys. 2021 Aug 12;23(31):16966-16972. doi: 10.1039/d1cp02710g.
We report a controlled polymer network gel electrolyte based on a multifunctional poly(ethylene glycol) (PEG) prepolymer (herein, tetrafunctional PEGs (tetra-PEGs) and bisfunctional linear PEGs (linear-PEGs)) and an ionic liquid (IL)-based electrolyte solution containing lithium bis(trifluoromethanesulfonyl)imide (LiTFSA) salt. The gel electrolyte was obtained via a gelation reaction, i.e., the Michael addition reaction between maleimide (MA)-terminated tetra-PEGs and thiol (SH)-terminated tetra- or linear-PEGs (termed tetra/tetra-PEG gel or tetra/linear-PEG gel systems), in a LiTFSA/IL solution under noncatalytic conditions at room temperature. For the tetra/linear-PEG system, the gelation reaction depended on the ratio of tetra-PEG-MA and linear-PEG-SH; an optimum terminal MA/SH ratio of 1 : 1 yielded a reaction efficiency (p) of ∼98% (an ideal polymer network structure). The tetra/tetra-PEG system with an MA/SH ratio of 1 : 1 also achieved a reaction efficiency of ∼98%. Time-resolved rheological measurements revealed that the network formation process can be categorized into three steps: (I) oligomer formation at an early stage of the reaction, (II) formation of a roughly linked polymer network with a large mesh size as the reaction proceeded, and (III) full network formation also at the local scale near the gelation completion time. The resulting tetra/linear-PEG ion gel with an optimum MA/SH ratio of 1 : 1 exhibited high stretchability, enduring approximately 10-fold elongation, and superior ion-conducting properties compared with the corresponding IL-based electrolyte solution.
我们报道了一种基于多功能聚乙二醇（PEG）预聚物（本文中为四官能团PEG（四臂PEG）和双官能团线性PEG（线性PEG））以及含有双（三氟甲磺酰）亚胺锂（LiTFSA）盐的离子液体（IL）基电解质溶液的可控聚合物网络凝胶电解质。该凝胶电解质是通过凝胶化反应制得的，即在室温下非催化条件下，在LiTFSA/IL溶液中，马来酰亚胺（MA）封端的四臂PEG与硫醇（SH）封端的四臂或线性PEG之间发生迈克尔加成反应（称为四臂/四臂PEG凝胶或四臂/线性PEG凝胶体系）。对于四臂/线性PEG体系，凝胶化反应取决于四臂PEG-MA与线性PEG-SH的比例；最佳的末端MA/SH比例为1∶1时，反应效率（p）约为98%（理想的聚合物网络结构）。MA/SH比例为1∶1的四臂/四臂PEG体系也实现了约98%的反应效率。时间分辨流变学测量表明，网络形成过程可分为三个步骤：（I）反应早期形成低聚物；（II）随着反应进行，形成具有大网孔尺寸的大致连接的聚合物网络；（III）在凝胶化完成时间附近的局部尺度上也形成完整网络。所得MA/SH最佳比例为1∶1的四臂/线性PEG离子凝胶表现出高拉伸性，可承受约10倍的伸长，并且与相应的IL基电解质溶液相比具有优异的离子传导性能。
