Highly conductive and tough double‐network hydrogels for smart electronics
Dong Zhang, Yijing Tang, Xiong Gong, Yung Chang, Jie Zheng
Abstract
Abstract Development and understanding of highly mechanically robust and electronically conducting hydrogels are extremely important for ever‐increasing energy‐based applications. Conventional mixing/blending of conductive additives with hydrophilic polymer network prevents both high mechanical strength and electronic conductivity to be presented in polymer hydrogels. Here, we proposed a double‐network (DN) engineering strategy to fabricate PVA/PPy DN hydrogels, consisting of a conductive PPy‐PA network via in‐situ ultrafast gelation and a tough PVA network via a subsequent freezing/thawing process. The resultant PVA/PPy hydrogels exhibited superior mechanical and electrochemical properties, including electrical conductivity of ~6.8 S/m, mechanical strength of ~0.39 MPa, and elastic moduli of ~0.1 MPa. Upon further transformation of PVA/PPy hydrogels into supercapacitors, they demonstrated a high capacitance of ~280.7 F/g and a cycle life of 2000 galvanostatic charge/discharge cycles with over 94.3% capacity retention at the current density of 2 mA/cm 2 and even subzero temperatures of −20 °C. Such enhanced mechanical performance and electronic conductivity of hydrogels are mainly stemmed from a synergistic combination of continuous electrically conductive PPy‐PA network and the two interpenetrating DN structure. This in‐situ gelation strategy is applicable to the integration of ionic‐/electrical‐conductive materials into DN hydrogels for smart‐soft electronics, beyond the most commonly used PEDOT:PSS‐based hydrogels.