A Novel Ionic Conductive Polyurethane Based on Deep Eutectic Solvent Continuing Traditional Merits

Artificial intelligence (AI) has become increasingly popular along with the development of the bionic neural system. Ionic conductors play an important role in the AI system due to the ability of bionic sensing and signal transporting. Traditional low-polarity elastomers possess outstanding mechanical strength and stability, such as polyurethane, which is difficult to be directly endowed with ionic conductivity without impairing its properties. Herein, we have first put forward a new approach to synthesize a liquid-free ionic conductive polyurethane (CPU) through one-step copolymerization between a green deep eutectic solvent (DES) and a prepolymer of polyurethane. The as-prepared CPU can retain the native properties of the traditional polyurethane (PU) such as the homogeneous phase, ease of molding, high transparency (about 93.3%), and excellent mechanical properties. By introducing the DES as the covalent cross-linking agent and ionic conductor at the same time, the CPU also has fine ionic conductivity (3.78 × 10^-5 S cm^-1), environmental resistance like anti-freezing (-20 °C), and solvent resistance. Based on the excellent conductivity and mechanical strength, the flexible CPU can be applied as a sensing element in pressure sensors. The CPU-based sensor has presented long-term stability, high sensitivity, and wide-ranging response (0.17-3.28 MPa) to the applied pressure, which will be suitable for the industrial demands for practical applications.