Fabrication of multifunctional polypyrrole hydrogel enhanced by polyvinyl alcohol

Stable polypyrrole (PPy)-based hydrogels as soft conducting materials are ideal in wearable electronics and elastic robotics. The development of high-performance PPy-based hydrogels is greatly desired due to the poor mechanical properties of PPy hydrogel. Here, multifunctional stable conducting hydrogels are fabricated by immersing the preprepared brittle PPy hydrogel into polyvinyl alcohol (PVA) solution followed by freeze-thaw cycles. The extensive hydrogen bonding between PPy and PVA and the entangled PVA chains further support the backbone structure of the interconnected PPy network, improving the mechanical performance of the hydrogel. PPy/PVA hydrogel exhibits attractive mechanical property with a compression strength of 70 kPa, satisfactory electrical conductivity (10 S m(-1)), good processability, and self-healing features. PPy/PVA/100 still retained a recovery rate of more than 90% even after 1000 cycles of 30% compression strain. Furthermore, the as-prepared hydrogel is applied to show high-quality electrochemical behavior of 120 F/g subjected to repeated compression and an electrically controlled release of fluorescein sodium with 0.70 & mu;g/mg at - 1 V for 12 h. This facile method supplies a promising strategy to fabricate soft materials with integrated electrical and mechanical properties for the potential applications in wearable devices and flexible energy electronics.