High-Strength, Self-Healable, Temperature-Sensitive, MXene-Containing Composite Hydrogel as a Smart Compression Sensor.

As a new two-dimensional material similar to graphene, MXene has attracted extensive attention in the field of electrochemical materials such as supercapacitors because of its excellent mechanical properties, electrical conductivity, and thermal conductivity. What is better than graphene is that the few-layer MXene material obtained by proper treatment has good water dispersibility and can be used as an ideal nanomaterial to enhance the conductivity of hydrogels. However, the articles about the few-layer MXene material used in the preparation of composite hydrogels are rare. In this paper, MXene was synthesized by Yury mild method. Poly(N-isopropyl acrylamide) (PNIPAM) hydrogel and physical cross-linking hydrogel were used as the matrix to prepare composite hydrogels with temperature sensitivity and stress-sensing properties. The composite hydrogels exhibited excellent mechanical properties: it could be stretched to over 14 times the original length and achieved a 0.4 MPa tensile strength while showing good self-healing ability, which was of great significance for the practical application of hydrogels. The conductivity of the composite hydrogel was 1.092 S/m, which was about 15 times that of the control hydrogel without MXene. The potential of the composite hydrogel as a smart compression sensor was also verified by the conductivity tests.