Dynamically morphing microchannels in liquid crystal elastomer coatings containing disclinations
Dynamically morphing microchannels in liquid crystal elastomer coatings containing disclinations
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DOI：
10.1063/5.0022193
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发表时间：
2020-11-14
影响因子：
3.2
通讯作者：
Lavrentovich, Oleg D.
中科院分区：
文献类型：
--
作者：
Babakhanova, Greta;Golestani, Youssef M.;Lavrentovich, Oleg D.
液晶弹性体（LCE）作为智能软涂层的多功能材料平台具有重要的前景，因为它们的取向顺序可以预先设计以编程所需的动态轮廓。在这项工作中，我们介绍了温度响应的动态涂层的基础上LCE与阵列的奇异缺陷，向错，运行平行于表面。向错响应于由等离子体激元掩模光配向施加的顶表面和底表面处的分子取向的拮抗图案而形成。在加热时，最初平坦的LCE涂层形成位于每个向错上方的线性微通道。在加热时引起LCE涂层的非平坦轮廓的刺激是由向错周围的分子取向梯度引起的激活力。为了描述微通道的形成及其热响应，我们采用了Frank-Oseen模型的向错在一个图案化的导演场，并提出了一个线性弹性理论连接复杂的空间变化的分子取向的位移的LCE。热响应的表面轮廓预测的理论和有限元建模与实验数据吻合良好，特别是，更高的梯度的分子取向产生更强的调制的涂层轮廓。弹性理论和有限元模拟使我们能够估计表征弹性体涂层对热激活的响应的材料参数。含有向错的LCE显示出作为具有预先设计的响应表面轮廓的软动态涂层的潜力。
Liquid crystal elastomers (LCEs) hold a major promise as a versatile material platform for smart soft coatings since their orientational order can be predesigned to program a desired dynamic profile. In this work, we introduce temperature-responsive dynamic coatings based on LCEs with arrays of singular defects-disclinations that run parallel to the surface. The disclinations form in response to antagonistic patterns of the molecular orientation at the top and bottom surfaces, imposed by the plasmonic mask photoalignment. Upon heating, an initially flat LCE coating develops linear microchannels located above each disclination. The stimulus that causes a non-flat profile of LCE coatings upon heating is the activation force induced by the gradients of molecular orientation around disclinations. To describe the formation of microchannels and their thermal response, we adopt a Frank-Oseen model of disclinations in a patterned director field and propose a linear elasticity theory to connect the complex spatially varying molecular orientation to the displacements of the LCE. The thermo-responsive surface profiles predicted by the theory and by the finite element modeling are in good agreement with the experimental data; in particular, higher gradients of molecular orientation produce a stronger modulation of the coating profile. The elastic theory and the finite element simulations allow us to estimate the material parameter that characterizes the elastomer coating's response to the thermal activation. The disclination-containing LCEs show potential as soft dynamic coatings with a predesigned responsive surface profile.