The preparation of dual cross-linked high strain composite gel with manifold excellent properties and its application as a strain sensor

Gel with satisfactory mechanical performance and reliability have received tremendous attention for their application. In this study, an elaborately designed dual cross-linked polyacrylamide/chitosan (PAM/CS) composite gel containing hydrogen bonds and coordination bonds was prepared by introducing phytic acid and cobalt ions into gel. During the preparation process, the oxidative polymerization and free water evaporation proceed simultaneously to obtain the gel by a water bath heating process. The PAM/CS gels possess excellent stretchability (∼3630%), self-adhesiveness, self-healing properties as well as self-extinguishing. Notably, the gel (PAM/CS-II) remains high strain after being placed for one month (0.22 MPa, 1022%) and even after heating or under the cold environment, demonstrating a long-term stability at room temperature and an extraordinary flexibility under a wide temperature spectrum. Extraordinary comprehensive properties can offer substantial benefit to their application, life span and security. PAM/CS-II gel can be directly employed as a strain sensor to evaluate the human motions, such as the subtle motion of the face and laryngeal knot. The human motions had been accurately detected with short response time by the strain sensor. This study strongly contributes to the strategy for the preparation and application for gel. The dual cross-linked polyacrylamide/chitosan composite gel possesses excellent stretchability, self-adhesiveness, self-healing properties, self-extinguishing as well as low-temperature resistance, and can be directly employed as strain sensor to evaluate the subtle human motion.