Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education of the People's Republic of China, Heilongjiang University, Harbin 150080, China.
Department of Applied Science, Harbin University of Science and Technology, Harbin 150080, China.
Molecules. 2023 Jun 20;28(12):4858. doi: 10.3390/molecules28124858.
Liquid crystal elastomers (LCEs) are shape-morphing materials whose large and reversible shape transformations are caused by the coupling between the mobile anisotropic properties of liquid crystal (LC) units and the rubber elastic of polymer networks. Their shape-changing behaviors under certain stimuli are largely directed by the LC orientation; therefore, various strategies have been developed to spatially modulate the LC alignments. However, most of these methods are limited as they require complex fabrication technologies or have intrinsic limitations in applicability. To address this issue, programmable complex shape changes in some LCE types, such as polysiloxane side-chain LCEs, thiol-acrylate main-chain LCEs, etc., were achieved by using a mechanical alignment programming process coupled with two-step crosslinking. Here, we report a polysiloxane main-chain LCE with programmable 2- and 3D shape-changing abilities that were created by mechanically programming the polydomain LCE with two crosslinking steps. The resulting LCEs exhibited a reversible thermal-induced shape transformation between the initial and programmed shapes due to the two-way memory between the first and second network structures. Our findings expand on the applications of LCE materials in actuators, soft robotics, and smart structures where arbitrary and easily programmed shape morphing is needed.
液晶弹性体（LCEs）是一种形状可变形的材料，其大的和可回复的形状转变是由液晶（LC）单元的可移动各向异性和聚合物网络的橡胶弹性之间的耦合引起的。它们在某些刺激下的形状变化行为在很大程度上受到 LC 取向的控制；因此，已经开发了各种策略来空间调节 LC 取向。然而，这些方法大多受到限制，因为它们需要复杂的制造技术，或者在适用性方面存在固有局限性。为了解决这个问题，一些 LCE 类型，如聚硅氧烷侧链 LCE、硫醇-丙烯酸酯主链 LCE 等，通过使用机械取向编程过程与两步交联相结合，实现了可编程的复杂形状变化。在这里，我们报告了一种具有可编程的 2D 和 3D 形状变化能力的聚硅氧烷主链 LCE，它是通过对具有两个交联步骤的多畴 LCE 进行机械编程来创建的。由于第一个和第二个网络结构之间的双向记忆，所得的 LCE 表现出初始和编程形状之间的可逆热诱导形状转变。我们的发现扩展了 LCE 材料在执行器、软机器人和智能结构中的应用，这些应用需要任意和易于编程的形状变形。
