From Event: SPIE Organic Photonics + Electronics, 2017
Mesoscopic hierarchical superstructures bridge the micro and macro worlds and play vital roles in natural materials. To mimic hierarchical organization in nature, one promising strategy is the convergence of top-down microfabrication and bottom-up self-assembly. Much efforts have been devoted to this field, but till now, the precise realization and rational control of large-area perfect hierarchical superstructures is still challenging. On the other hand, Smectic liquid crystals (SLCs) are formed by flexible molecular layers of constant thickness. If the nanometer-thin smectic layers can be manipulated in an origami manner, a Japanese art that constructs various 3D objects via folding pieces of papers, brand new hierarchical superstructures possessing exceptional features then could be realized. In this work, the smectic layer origami is accomplished via preprogrammed photoalignment. The principle is rooted in the anisotropy of molecular interactions at interfaces, which makes the preset patterned alignment favoring a certain layer bending of adjacent SLCs, and subsequently dominating the configuration of entire family of smectic layers. Thanks to the excellent flexibility of photoaligning, the unit geometry (shape, size and orientation) as well as the clustering characteristic (lattice symmetry) of fragmented TFCDs can be rationally designed and freely manipulated over square centimeters. The obtained fragmented toric superstructures break the rotational symmetry while maintain the radially gradient director field, enabling metasurface-like direction-determined-diffraction. We believe this work is an important step toward extending the fundamental understanding of self-assembled soft materials and enhancing the construction of possible hierarchical superstructures. It may inspire extra possibilities in advanced functional materials and fantastic photonic applications.
Yan-Qing Lu and Wei Hu, "Smectic layer origami based on preprogrammed photoalignment (Conference Presentation)," Proc. SPIE 10361, Liquid Crystals XXI, 103610E (Presented at SPIE Organic Photonics + Electronics: August 06, 2017; Published: 19 September 2017); https://doi.org/10.1117/12.2275927.5581145285001.
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