Dynamic surfaces which can change their topography with external stimuli have wide application prospects. Liquid crystal network (LCN) is an ideal material for making dynamic surfaces, but traditional methods for LCN dynamic surface manufacturing are difficult to scale up, which limits its applications. This research proposes a new method to fabricate a responsive surface using ink-jet printing technology. Using a liquid crystal monomer mixture as the ink, we printed arrays of droplets onto a glass substrate with a homeotropic alignment layer and polymerized the droplets into deformable LCN hemispheres. An azobenzene diacrylate was copolymerized into the hemispheres to make them photo-responsive to UV light. Because the ink-jet printing method can potentially be used to print countless hemispheres on a large area substrate, large area dynamic surfaces consisting of a multitude of separate dynamic structures can be manufactured. Since the deformation of the entire surface is a periodic repetition of the deformation of a single hemisphere, we characterized the deformation of individual hemispheres, and found that the optical image of hemispheres between crossed polarizers shows a “maltese cross” texture, and 3D surface profiling shows the top surface depresses into a valley after UV-irradiation. This is caused by an order parameter decrease of the homeotropically aligned LC molecules, which leads to a contraction in the alignment direction. The deformation amplitude can be modulated by UV intensity and temperature. This kind of dynamic surface fabricated by ink-jet printing technology can easily be scaled up and is promising for applications such as adjustable micro-lenses or surface wettability.

中文翻译：

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通过喷墨印刷制造的可光变形的动态表面

可以通过外部刺激改变其形貌的动态表面具有广阔的应用前景。液晶网络（LCN）是用于制造动态表面的理想材料，但是用于LCN动态表面制造的传统方法很难扩大规模，这限制了其应用。这项研究提出了一种使用喷墨打印技术制造响应表面的新方法。使用液晶单体混合物作为墨水，我们将液滴阵列印刷到具有垂直排列层的玻璃基板上，并使液滴聚合成可变形的LCN半球。将偶氮苯二丙烯酸酯共聚到半球中，以使其对紫外线具有光响应性。由于喷墨打印方法可以潜在地用于在大面积基板上打印无数个半球，可以制造由多个单独的动态结构组成的大面积动态表面。由于整个表面的变形是单个半球变形的周期性重复，因此我们对单个半球的变形进行了表征，发现交叉偏振器之间的半球光学图像显示出“马耳他十字”纹理，并且3D表面轮廓图中显示了在紫外线照射后顶面凹陷成一个山谷。这是由于垂直排列的LC分子的阶数参数减小而导致的，这导致排列方向上的收缩。变形幅度可以通过紫外线强度和温度来调节。