Zwitterionic liquid crystal elastomer with unusual dependence of ionic conductivity on strain and temperature for smart wearable fabric

Abstract

Stretchable ionic conductors are appealing for soft electronics, yet frequently had their conductivities limited below the level desired by many applications, and also lack the ability of simultaneously actuating and sensing their own motions, resembling living organisms’ neuromuscular behaviors. In this study, by introducing a zwitterionic chain extender into liquid crystal elastomers (LCEs) backbones, a unique type of zwitterionic LCEs (iLCEs) fiber with ionic conductivity of 2.3 S m−1 and self-sensing properties was designed. By controlling the anisotropy solvent evaporation, the iLCEs fiber with certain degree of mesogenic alignment was easily obtained. The mesogenic alignment not only enabled a reversible actuation behavior, but also boosted the formation of ionic channels for an abnormal dependence of ionic conductivity on temperature and elongation. The resultant iLCEs fibers showed an increasing resistance at high temperatures, and a decreasing resistance at large tensile strain, in contrast to the liquid-like mechanism of ion transport for ionogel systems. This combination of actuation and ionic conductance promises great potential in applications of self-sensing actuation and self-perception of soft robots.