Resilient and Tough Conductive Polymer Hydrogel for a Low‐Hysteresis Strain Sensor

Abstract Conductive polymer hydrogels are vital in strain sensors, yet achieving high resilience and toughness is a challenge. This study employs a prestretch method to engineer a tough conductive polymer hydrogel with sufficient resilience. Initially, a blend film of polyvinylalcohol (PVA) and ethylene‐vinyl alcohol copolymer (EVOH) is prepared through solution casting, followed by a swelling process to form a PVA‐EVOH hydrogel. This hydrogel, with PVA crystallites as crosslinking points, exhibits high toughness. The hydrogel is then immersed in pyrrole and ferric chloride solutions for in‐situ polymerization of polypyrrole (PPy), creating a conductive PPy/PVA‐EVOH hydrogel. Finally, a 200% prestretch is applied, breaking short chains within the network, eliminating energy dissipation at low strains. This results in a hydrogel with a 100% elastic deformation range, while maintaining high fracture toughness (1700 J m ‐2 ). The prestretched PPy/PVA‐EVOH hydrogel functions as a strain sensor with low hysteresis, providing consistent strain measurements during loading and unloading. This outperforms the non‐prestretched sample, which shows inconsistent responses between stretching and releasing.