Tuning Flexibility-Rigidity Conversion of Liquid Metal/Polyurethane Composites by Phase Transition for Potential Shape Memory Application

Composites with the capability of rigid variation through environmental stimulus have attracted great attention, attributing to their huge potential for shape memory electronics. To date, the rigid variation of composites stimulated by the body temperature is still a great challenge. Herein, the liquid metal-coated polyurethanes (PUs) that have flexibility-rigidity transition properties due to the presence of a gallium coating that can undergo phase transition from solid to liquid in response to body temperature heating are described. The liquid metal particles are bonded onto the PU skeleton treated by microwave plasma elastic, constructing liquid metal/PU composites. The strong oxidizing ability of gallium forms a thin Ga2O3 oxide film constructing a shell structure of the stable particle. Such novel strategy consists of the elastomeric skeleton and the gallium phase switching coating, making the fabricated composites capable of mechanical tunability. The modulus of composites can turn from 35 to 2008.9 kPa and return to 35 kPa under the body temperature, which allows for a convenient and simple method to produce shape memory effects. This approach provides a straightforward method to stimulate shape memory properties through the body temperature. Thus, they may be suitable for new applications in soft electronics.