Title: A Liquid Crystal Polymer with Thermally-Induced Deformation and Reversible Fluorescence Switching

Author: Xin Zhao, Ziyue Yang, Xiaoyu Zhang, Xiaojun Liu, Yu Pu, Lang Qin, Jia Wei*, Yanlei Yu*

Journal:  Adv. Optical Mater., 2025, 12, 2403469

Abstract:

Stimuli-responsive liquid crystal polymers (LCPs) hold significant promises as materials for designing multifunctional soft actuators. Recently, this group explored a novel strategy to develop a multi-responsive LCP by combining ring-opening metathesis polymerization (ROMP) with post-polymerization modification (PPM). The current study aims to advance the approach to design an LCP capable of thermally-induced deformation and fluorescence switching. ROMP is first employed to synthesize a reactive linear LCP precursor containing aggregation-induced emission luminogens (AIEgens) with excellent processability, enabling the preparation of arbitrary shapes through various processing techniques. Subsequently, PPM is responsible for anchoring the mesogen alignment of the as-prepared film and fiber geometries. The obtained cross-linked LCP films and fibers undergo contraction, bending, unfolding and rolling with increasing temperature. Furthermore, the disruption of mesogen at high temperature weakens the restriction of AIEgen motions, facilitating the switching of the fluorescence property of LCPs. This material design combines the diverse fabrication opportunities, advanced actuation capabilities, and the tunable emission properties of AIEgens, while also enabling the visualization of the actuator's state.

Fulltext Link: https://onlinelibrary.wiley.com/doi/10.1002/adom.202403469

Liquid crystal polymers(LCP) with deformation and color-changing functions can be used to construct soft robots with both actuation and feedback functions. In this study, we utilized the phase transition of the liquid crystal mesogens to achieve the above functions. Firstly, we prepared a liquid crystal polymer precursor with excellent processability through ring-opening metathesis polymerization (ROMP). Fluorescent groups with aggregation-induced emission (AIE) properties and reactive pentafluorobenzyl groups were introduced into the LCP to endow it with fluorescence color-changing performance and reactive cross-linking sites, respectively. Secondly, by taking advantage of the good processability of the linear precursor, we programmed it as a 1D to 3D actuator with good liquid crystal orientation. Through post-polymerization modification (PPM) to fix the orientation and macroscopic shape of the liquid crystal units in the material, we achieved the visualization of driving performance and fluorescence intensity changes, providing a material basis for constructing multimodal and multifunctional LCP soft robots.