Hydrogen-bonding-assisted toughening of hierarchical carboxymethyl cellulose hydrogels for biomechanical sensing

Herein we present a CMC based hydrogel that can be engineered for texture by applying a soaking strategy after freeze-thaw. These two processes lead to a hierarchal structure within the CMC polymer hydrogels. Such hydrogels can be strain hardening; that is the gel modulus increases with higher strain levels. Both the failure stress and energy are high (1.54 MPa and 9.94 kJm^-2 respectively). At sub-failure strains, the hydrogels show a high degree of recoverability as evidenced by their minimal hysteresis in a stress-strain test. Furthermore, these hydrogels are electrically conductive making them good candidates for tough sensors and wearable electronic devices.