Adhesive, Conductive, Self-Healing, and Antibacterial Hydrogel Based on Chitosan–Polyoxometalate Complexes for Wearable Strain Sensor

In addition to conductivity, recent evidence suggests that adhesive, self-healing, and antibacterial properties are also important aspects of wearable force sensors. However, preparation of hydrogel with these combined aspects in a facile strategy is still a challenge. In this paper, a simple method is proposed to obtain adhesive, conductive, self-healing, and antibacterial chitosan–polyoxometalate (POM) hydrogel. First, silicotungstic acid (SiW) was added into a chitosan solution to form a chitosan–silicotungstic acid (CS/SiW) physical cross-link network. Second, the CS/SiW–poly(acrylamide) (PAM) double-network hydrogels were fabricated by the in situ polymerization of acrylamide (AM). The CS/SiW-PAM hydrogel indicated excellent repeatable adhesive capacity on the surface of various materials. The CS/SiW-PAM hydrogel also displayed highly sensitive conductivity upon strain. Moreover, the CS/SiW-PAM hydrogel had outstanding self-healing and antibacterial properties. As a result, it is envisioned that the present work will broaden the path for development of POM-based functional soft materials for various applications.