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Preparation of Supramolecular Ionic Liquid Gels Based on Host–Guest Interactions and Their Swelling and Ionic Conductive Properties
- Sinawang, Garry, Kobayashi, Yuichiro, Zheng, Yongtai, Takashima, Yoshinori, Harada, Akira, Yamaguchi, Hiroyasu
- Macromolecules 2019 v.52 no.8 pp. 2932-2938
- composite polymers, copolymerization, crosslinking, electrochemistry, gamma-cyclodextrin, gels, ionic liquids
- Ionic liquid gels (IGs) have received much attention due to their electrochemical properties. IGs previously reported were formed by chemically cross-linked structures. The ionic conductivity (σ) of chemically cross-linked IGs was one order of magnitude lower than that of the native ionic liquid. Supramolecular polymeric IGs based on noncovalent bond cross-linkers have the potential to realize higher σ values. We prepared supramolecular polymeric IGs based on host–guest interactions. The supramolecular polymeric IG was prepared from bulk copolymerization of the host–guest complex between peracetylated γ-cyclodextrin (PAcγCD) and 2-ethyl-2-adamantane (Ad) in the presence of acrylate followed by immersing the copolymer in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIm TFSI). The σ value of the supramolecular polymeric IG was higher than those of the chemically cross-linked IGs. Although the σ values of the chemically cross-linked IG, Ad with chemically cross-linked IG, and PAcγCD with chemically cross-linked IG based on poly(ethyl acrylate) showed low σ values (0.54, 0.50, and 1.6 mS/cm, respectively), the σ value of the supramolecular polymeric IG based on poly(ethyl acrylate) reached 8 mS/cm, which is comparable to that of EMIm TFSI (9 mS/cm). These results indicated that the host–guest interaction in the supramolecular polymeric IG increases the σ value.