Thermochromic Liquid-Crystalline Elastomers Featuring a Predesigned Hybrid Architecture

Abstract

Liquid-crystal elastomers have recently found diverse applications in mimicking biological functionalities, largely due to the unique interactions among liquid-crystal molecules. One intriguing application involves replicating the transformation and color-changing abilities of chameleons using dual-layer liquid-crystal elastic films. However, these films often exhibit defects due to the presence of a laminating layer. Addressing this issue, our study presents an approach where we design liquid-crystal molecule alignment and employ ultraviolet polymerization to fabricate a hybrid liquid-crystal film actuator with inclined alignment, effectively overcoming these defects. By integrating cholesteric liquid crystals with vertically aligned nematic liquid-crystal layers, our actuator demonstrates both shape-changing and thermochromic capabilities. We confirm the alignment of liquid-crystal molecules through field emission scanning electron microscopy and polarized optical microscopy, while the structural color of the films is examined using a UV–visible spectrometer. As the temperature rises, our prepared liquid-crystal films exhibit a bending thermomechanical effect, coupled with a redshift in color during thermal stimulation. Notably, our dual-layer films doped with E7 show heightened color variation and undergo rigorous cycle testing for reversible bending actuation, leveraging the unpolymerized nature of E7. These meticulously designed hybrid liquid-crystal films hold promise for applications in soft robotics, artificial muscle development, and optical devices.