Fabrication of Highly Robust and Conductive Ion Gels Based on the Combined Strategies of Double-Network, Composite, and High-Functionality Cross-Linkers

A robust hybrid ion gel is fabricated utilizing the combined strategies of double-network (DN), composite, and high-functionality cross-linkers. The charged poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) constructs the DN skeleton, with graphene oxide (GO) and N,N′-methylenebisacrylamide (MBA) being the cross-linkers for the first and second networks, respectively. The ionic liquid, either 1-ethyl-3-methylimidazolium dicyanamide ([EMIm][DCA]) or 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]), is locked in the network to offer the high conductivity. Compared to the DN PAMPS ion gel without nanoparticles and the hybrid DN ion gel with unconnected silica nanoparticles, the present ion gel exhibits a significantly higher tensile strength (3.2 ± 0.1 MPa) and an excellent compressive strength (26 ± 1 MPa). The [EMIm][DCA] ion gel has a high conductivity close to that of its neat ionic liquids. The conductivity of the gel is sensitive to deformation and temperature, which leads to potential applications in sensing body movements, pulse, and temperature change.