Oscillatory dynamic surface structures in patterned liquid crystal network coatings
Oscillatory dynamic surface structures in patterned liquid crystal network coatings
复制标题
图案化液晶网络涂层中的振荡动态表面结构
DOI：
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
D. Broer
中科院分区：
文献类型：
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作者：
M. Hendrikx;Danqing Liu;A. Schenning;D. Broer
表面形貌的可控形成导致了一系列有趣的应用(摩擦控制、细胞黏附和运动、自清洁等)。利用光敏分子与液晶网络(LCN)涂层相结合，可以在辐射时创建表面结构。对于这些LCN涂层，取向决定了表面的形状，从而决定了材料的应用。一种出色的局部控制液晶取向的方法是利用所谓的光取向层。在这里，我们提出使用这样的一层与偶氮苯掺杂的LCN涂层相结合，以产生可用于振荡变形的不同形状的形貌。制备了具有不同平面排列和缺陷线的偶氮苯掺杂LCN涂层。在紫外光驱动下，我们得到了由缺陷的对称性定义的不对称或对称的形貌。通过这种方式，我们创建了渐近、丘陵、山谷或连续的正弦地形。此外，我们还表明，这些拓扑图可以在本地寻址。我们利用偏振紫外光和蓝光相结合来控制偶氮苯交联剂的顺式和转化式，从而诱导了这些振荡形变。由于偶氮苯具有二向色性，这种照明方法会导致偶氮-LCN涂层的局部激活。当线偏振紫外光旋转时，驱动变为振荡，表面结构动态。
Controlled formation of surface topographies has led to an interesting set of applications (friction control, cell adhesion and motility, self-cleaning and many more). Utilizing light-sensitive molecules in combination with liquid crystal network (LCN) coatings allows for the creation of surface structures upon irradiation. For these LCN coatings, the alignment determines the shape of the topography and thus the application of the material. An outstanding method to control the alignment of the liquid crystals locally, is utilizing a so-called photo-alignment layer. Here, we present the use of such a layer in combination with azobenzene-doped LCN coatings to create different shapes of topographies that can be used for oscillatory deformations. Azobenzene-doped LCN coatings were made with different planar alignments and defect lines. Upon UV light actuation, we obtained asymmetric or symmetric topographies defined by the symmetry of the defect. In this way we create asymptotic, hills, valleys or continuous sinusoidal topographies. In addition we show that these topographies can be addressed locally. We induced these oscillatory deformations by utilizing polarized UV light in combination with blue light to control the cis and trans formation of the azobenzene crosslinker. Since the azobenzene has dichroic properties, this illumination method induces a local actuation of the azo-LCN coating. Upon rotation of linear polarized UV light, the actuation becomes oscillatory and the surface structures dynamic.