A novel highly stretchable, freeze-resistant, and recyclable organohydrogel by waterborne polyurethane and DMSO-H2O binary solvent enhanced for multifunctional sensors

Abstract

Conductive hydrogels have gained significant attention for wearable devices in recent years. However, hydrogel suffers from limitations such as poor stretchability, freezing under cold climates, and drying out in harsh environments, which restrict its practical applications. To address these issues. We synthesize waterborne polyurethane (WPU) and add it to the polyvinyl alcohol (PVA) hydrogel to enhance its mechanical properties. Additionally, DMSO is introduced to the system, aiming to enhance the environmental stability of the hydrogel through its interaction with water. Hence, we prepare a novel organohydrogel by incorporating WPU into PVA in a dimethyl sulfoxide (DMSO)-water (H2O) binary solvent system by one-pot method. The addition of DMSO and WPU enhances the mechanical properties of the organohydrogel, resulting in high mechanical strength (1.27 MPa), excellent stretchability (874%), and superior toughness (3.62 MJ/m3). In addition, the organohydrogel presents reliable freeze resistance and water retention properties due to DMSO interaction with water. More significantly, the organohydrogel can be recycled and reshaped into various shapes through a simple process. The reconstructed organohydrogel still has the original's mechanical properties and sensing capabilities and can continue to be used in flexible electronic devices. Moreover, the organohydrogel is developed for flexible multifunctional sensors, exhibiting high sensitivity (G = 1.89), a rapid response time (141 ms), and exceptional fatigue resistance (100 cycles). Notably, the sensor signals remain stable even after storage in extreme conditions. This study expands the working field of flexible hydrogel sensors and provides a new idea for the sustainable development of next-generation flexible hydrogel sensors.