Polyionic liquid ionogels formed via hydrophobic association for flexible strain sensors

Abstract

In recent years, self-healing conductive hydrogels have attracted much attention for their promising applications in flexible electronic devices. However, the development of integral conductive hydrogels with excellent mechanical, self-healing, anti-freezing and strain-sensitive performances remains a major challenge. In this study, a series of self-healing polyionic liquid (PIL) ionogels based on vinyl choline-amino acid ionic liquids (Cho-AA VILs) via hydrophobic association (HA) with high mechanical strength and electrical conductivity were prepared by micellar copolymerization. The effects of the amount and type of Cho-AA VILs on the performances of PIL ionogels were investigated. Due to the reversibility of dynamic coordination interactions, including hydrophobic association, hydrogen bonding as well as electrostatic interactions, the resulting PIL ionogels demonstrated favourable self-healing ability. The integration of the Cho-AA VILs enabled the PIL ionogels to provide sensitive, fast and stable strain sensing at room and low temperatures. Notably, the PIL ionogel sensor was capable of monitoring and distinguishing large and small human movements. These results indicated that Cho-A_X ionogels have promising applications in intelligent and flexible electronic devices.