Zwitterion-Induced Highly Self-Healable and Stretchable after Self-Healing Hydrogel Thermocell with High Thermopower for Heat Harvesting

Abstract

Thermocells receive intensive attention in recent years owning to the capability of converting heat to electricity with great thermopower. However, it is still lack of effective thermocells to satisfy the development of self-powered wearable electronics. Herein, by interpenetrating zwitterionic polymer (poly([2-(methacryloyloxy)ethyl]- dimethyl-(3-sulfopropyl)ammonium hydroxide)) (P(SBMA)) into polyethylene glycol (PEG) network via chemical polymerization to prepare dual-network hydrogels, we successfully fabricate hydrogel thermocells with high self-healability (90%), stretchability after self-healing (344%) and thermopower (3.5 mV/K). In detail, zwitterions not only enable the hydrogel promising self-healability due to strong electrostatic interaction, but also greatly boost thermocell performance owning to the enlarged structural entropy difference. Specially, hydrogel thermocells as self-powered wearable energy converter are demonstrated based on the stable lit LED lamp and thermovoltage output at extreme conditions including self-healing and stretching after self-healing. This work provides an effective strategy to develop promising thermocells for self-powered wearable electronics.

Keywords: hydrogel thermocell, zwitterion, self-healability, stretchability after self-healing, thermopower.