Synchronous differential orientation of liquid crystal elastomers based on dual dynamic covalent bonds†

Abstract

As a unique type of intelligent material, liquid crystal elastomers (LCEs) have numerous valuable advantages and show significant potential for application in the design of flexible actuators. Nevertheless, attaining controllable and precise orientation of LCEs using easily operated methods continues to pose a considerable challenge. In this study, a synchronous differential orientation strategy based on dual dynamic covalent bonds (DCBs) was proposed to solve these problems. Through the integration of dynamic boronic ester bonds and dynamic siloxane bonds into the LCE network, bilayer LCE films that exhibit distinct orientation configurations can be easily fabricated. Meanwhile, the variation in the bond energy between these two chemical bonds provides the ability to control the orientation of each layer separately, resulting in LCE films with adjustable bending angles. Furthermore, the addition of azobenzene to the LCE composition enables the material to undergo reversible bending when illuminated with alternating ultraviolet and visible light, revealing the potential for various actuation capabilities in innovative materials. This approach not only dramatically enhances the self-healing, programming, and recycling of LCEs, but also paves the way for the development of advanced flexible actuators with complex deformation properties, holding substantial potential for applications in robotics, biomedicine, and intelligent devices.