Electric field-controlled on-demand surface deformation in liquid crystal polymer networks with topological defects

Reconfigurable surface morphing control of liquid crystalline polymer (LCP) films at micro or nano scales has emerged as a promising strategy for various applications. Creating reproducible and adjustable platforms enhances their versatility. This study presents a method for controlling stimuli-responsive deformations in liquid crystal polymer network (LCN) films by forming defect arrays using a three-dimensional (3D) electric field generated by crossed electrode systems. The director field of the system can be simulated, enabling investigation of high-temperature deformations through activation force density calculations. To explain the laterally asymmetric deformation of our film, a 3D analysis of the activation force density vector field was essential. Topographical modifications at room temperature are also achieved by incorporating dichroic dye to the monomeric mixture, which promote local monomer diffusion during photopolymerisation. Additionally, by varying the configurations of signal and ground electrodes, different defect structures are generated, leading to distinct deformation patterns at elevated temperatures. Our findings demonstrate that LCN films in this study exhibit programmable nanometre-scale shape deformations, allowing for varied surface patterns from a single setup. This platform significantly enhances the potential of nano- or micro-morphing LCP coatings for advanced applications across multiple fields.

微米或纳米尺度下液晶聚合物（Liquid Crystalline Polymer, LCP）薄膜的可重构表面形变调控，已成为面向多类应用的极具前景的技术策略。构建可重复且可调节的调控平台，可有效提升其应用通用性。本研究提出一种调控方法：通过交叉电极系统产生的三维（3D）电场构建缺陷阵列，以此实现对液晶聚合物网络（Liquid Crystal Polymer Network, LCN）薄膜刺激响应形变的精准控制。该体系的指向矢场可通过模拟得到，进而可通过激活力密度计算开展高温形变相关研究。为阐释本研究中薄膜的侧向非对称形变，对激活力密度矢量场开展三维分析是必要的。通过在单体混合液中掺入二向色性染料，可在室温下实现薄膜的形貌调控——该染料可在光聚合过程中促进单体的局部扩散。此外，通过改变信号电极与接地电极的配置方式，可生成不同的缺陷结构，进而在高温环境下得到各异的形变模式。本研究结果表明，所制备的LCN薄膜可实现可编程的纳米级形状形变，仅需一套实验装置即可生成多样化的表面图案。该平台显著提升了微纳形变LCP涂层在多领域高端应用中的应用潜力。