Sodium alginate-enhanced MXene multifunctional hydrogel: Dual temperature-strain response and recyclability

Conductive hydrogels are valued for their flexibility and sensitivity for flexible wearable sensors, but they typically focus on strain sensing and lack features such as fast temperature response. In addition, discarded sensors can cause environmental problems. Based on this, we developed a novel G₂B₃M₄ hydrogel using NIPAAm, AM, PDA@BN, MXene, and SA to achieve dual response to temperature and strain as well as reuse after disposal. The addition of the copolymerized hydrophilic monomer AM successfully changed the lowest critical solution temperature (LCST) of G₂B₃M₄ to approach the normal body temperature. In addition, the excellent dispersion of PDA@BN in the G₂B₃M₄ hydrogel not only improved its temperature sensitivity (TCR = −1.953 %/°C) but also resulted in a high stress (730.38 kPa), strain (6994.18 %), elasticity (49.14 kPa) and toughness (2644.17 KJ/m³). In addition, the abundant catechol groups, amino groups and carboxyl groups in G₂B₃M₄ hydrogel not only make it have good adhesion to various substrates but also can be used as a template to reduce Ag⁺ to Ag NPs to serve as a catalyst for the efficient degradation of dye wastewater. The hydrogel has good application prospects in the field of flexible sensors.