Preparation of (2 × 4)-type tetra-PEG ion gels through Cu-free azide–alkyne cycloaddition

(2 × 4)-Type tetra-PEG ion gels were prepared through a copper-free azide–alkyne cycloaddition reaction between azide-functionalized tetra-branched poly(ethylene glycol) and electron-deficient alkyne-functionalized tetra(ethylene glycol) in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. The thermal, mechanical, and electrochemical properties of the ion gels were characterized. The tensile tests showed that the reaction efficiency of the cross-linking was over 90%. The prepared ion gels exhibited high mechanical toughness and stretchability characteristic of tetra-PEG gels. The electrochemical window of the ion gels was the same as that of the ionic liquid inside the gel. The ionic conductivities of the ion gels with 30 and 50 wt% polymer concentrations were 8.9 and 1.4 × 10−4 S cm−1, respectively (25 °C, anhydrous conditions).