An ultrafast gelation based on catechol-metal ion dual self-catalysis used for 3D-printed dual-strain coaxial yarn

Abstract

Hydrogels have achieved remarkable applications in intelligent sensing for their excellent performance. However, the traditional fabrication of such gels always requires a complex process with external stimuli, such as high-temperature and additional catalysts, bringing inconvenience and restrictions in broadscale application promotion. Hence, a novel and ultrafast self-catalysis initiation system is established by the special redox equilibrium among tannin acid (TA), iron (Fe3+) and ammonium persulphate (APS) with multi-functional capabilities. Based on it, a dual-train coaxial hydrogel yarn was manufactured by the selective coaxial ink 3D printing method, with excellent mechanical properties, temperature sensitivity and conductivity. The gelation time and mechanical properties of the hydrogel can be changed by adjusting the quality of Fe3+. Moreover, by introducing N-isopropyl acrylamide (NIPAM) with a lower critical solution temperature, the hydrogel yarn may be used to monitor the environmental temperature through the temperature-conductivity responsiveness, which implies their potential as smart materials for real-time temperature sensor.