The design of multi-functional ionic hydrogels with anti-freezing, temperature response and luminescence properties

Abstract

Ionic hydrogels with designable properties that can detect a broad spectrum of stimuli and have the potential for the preparation of flexible electronic devices are available. However, the incorporation of structurally ameliorated zwitterionic monomers can further enhance the performance of ionic hydrogels and provide them with more functions. In this study, we synthesized a new class of zwitterionic monomers (CNPU) with hydroxyurethane chromophores using a straightforward method and subsequently fabricated a double-network ionic hydrogel, containing as-synthesized zwitterionic monomers and common gelation monomers. The luminescent monomer CNPU provides the hydrogels with fluorescence properties, while the double network structure imparts robust mechanical properties. Furthermore, the abundant hydrogen bond and electrostatic interaction give excellent fatigue resistance and anti-freezing properties (−28.70 °C) to the hydrogel. Ultimately, this hydrogel, characterized by high ionic conductivity (81.08 mS cm⁻¹) and temperature-sensitive sensing, was utilized to develop temperature sensors with remarkable anti-strain interference capabilities (GF = 0.16) and versatile applications including fluorescence positioning and information storage. Given its numerous advantages, this double-network ionic hydrogel exhibits tremendous potential for practical application in flexible sensors.