Tough, self‐healing double network hydrogels crosslinked via multiple dynamic non‐covalent bonds for strain sensor

Abstract

AbstractDouble‐network hydrogels have outstanding mechanical characteristics but mostly suffer from poor self‐healing performance since most hydrogels are chemically crosslinked via covalent links for each network. In this work, a tough and self‐healing double network hydrogel with multiple dynamic non‐covalent bonds is developed by combining the hydrophobically modified polyacrylamide (HPAM) with a thermally reversible potassium ion crosslinked κ‐carrageenan (K+C) network through a dual physical crosslinked network strategy. Being the multiple dynamic non‐covalent bond interactions and dual physical crosslink networks, the K+C/HPAM DN hydrogel exhibits excellent mechanical characteristics (tensile strength: 1.86 MPa, tensile strain: 1637%) and good self‐healing ability (maximum stress self‐healing efficiency: 87%, maximum tensile strength after self‐healing: 0.95 MPa). Due to the three‐dimensional pore structure and the conductive ions in the system, the K+C/HPAM DN hydrogel also achieves good strain sensing capabilities with a strain sensitivity of 2.98 (gauge factor, GF) in the 100% strain range. Even after being cut and self‐healed, the gel still exhibits good strain sensing capabilities (GF = 2.79), which is still better than the most similar DN hydrogel strain sensors in sensitivity. We believe this work offers a new material for self‐healing flexible strain sensors.