Liquid metal based electrical driven shape memory polymers

Abstract

Electrical driven shape memory polymers (SMPs) have received lots of attention due to their unique electrical-deformation behaviors. Traditional electrical active SMPs are usually based on rigid metals or carbon (such as carbon black and carbon nanotube) polymer composites, which suffer from low flexibility, poor deformation ability and high applying voltages. Here, we reported a liquid metal (LM)-based electroactive SMP by introducing liquid metal into the typical shape memory polymer, polycaprolactone (PCL). The resulted LM-SMP film was highly flexible and showed strain dependent electrical conductivities. With 30% volume LM loading, LM-SMP-30% exhibited a unique transition from insulator to conductor upon stretching. LM-SMP exhibited excellent shape memory performance with a shape fixation rate of 95% and a shape recovery rate of 99%. More importantly, LM-SMP could be electrically driven at low voltages (~2 V) ascribe to phenomenal conductivity of liquid metal. In addition, a reversible actuator was fabricated based on LM-SMP bilayer films, which showed reversible actuation under low external voltages. This work showed that the combination of SMP and LM could be a promising technique for electrical driven systems including soft robotics and advanced electronics.