Stretchable current collectors based on carbon embedded in a poly (acrylamide)/poly (N,N-methylenebisacrylamide) hydrogel modified with Nafion 117®

Abstract In this study, we optimized the dispersion of hydrophobic carbons within ionically conductive hydrogels composed of a poly (acrylamide)-pAAm/poly (N,N-methylenebisacrylamide)-pMBAA modified with Nafion 117®. The carbon-embedded hydrogel films were prepared by in situ UV polymerization of aqueous suspension containing KCl, acrylamide and N,N-methylenebisacrylamide monomers, the multi-walled-carbon nanotubes, graphene, single-walled carbon nanohorns, and their composites with polypyrrole. These electrodes were translucent, stretchable, ionically and electronically conductive at low carbon content. In addition, they were very flexible, reaching a stretch up to 1475.57% of their initial length. Mechanical characteristics and conductivity were measured at their maximum hydration, corresponding to water uptake of 47.20% after 5 days of curing in humidity chamber. Hydrogels with dispersed carbon demonstrated both ionic and electronic conductivity in hydrated state and electronic conductivity alone when the electrode was dry. Nafion 117® acted as a surfactant and played a significant role in the improvement of carbon distribution within the hydrogel due to the hydrophobic–hydrophilic interaction between hydrogel, Nafion and the carbon. This was further correlated with changes in zeta potential at the carbon–hydrogel interface upon addition of Nafion, measured using a rotating disk electrode voltammetry. Graphical abstract