Photo-Aligning Molecular Orientations in Liquid Crystal Polymers into Complex Patterns for Programmable Origami

受日本折纸艺术的启发，程序化折纸正在成为一种通过自动折叠二维材料薄片来制造三维物体的新途径。为了实现程序化折纸，小尺度可编程折纸机构是实现程序化折纸的关键和难点。液晶聚合物是带有棒状或圆盘状分子单元的弱交联聚合物。当这些分子单元以不均匀的方向模式排列时，液晶聚合物可以被外部刺激（如温度和光）触发自变形。该奖项支持基础研究，以开发在小长度尺度上排列复杂模式的分子取向所需的技术，并获得关于如何设计分子取向模式以实现所需的三维微观结构的基本理解。三维微结构在传感器、致动器、药物输送和光子器件等各种工业应用中都是非常需要的。这项研究的结果应该对美国经济做出贡献，并造福社会。这项跨学科的研究为培养研究生和本科生在光子学、液晶科学与技术、纳米制造和数值建模方面的知识和技能提供了一个很好的机会，并通过招收少数民族和高中生来增强多样性。程序折纸有望通过二维材料或结构的自折叠来制造奇异的三维微纳米结构。本项目旨在发展液晶聚合物薄膜在分子取向场的折叠轨迹刻印能力。研究一种用于确定复杂分子取向顺序的新型光图像化技术。它将对分子取向和自折叠过程之间的关系有一个基本的了解。研究团队将(1)设计、模拟、制造和表征所需分子取向模式的等离子体光掩膜；(2)开发用于光对准材料曝光的光学曝光系统；(3)设计、建模和制作嵌入分子取向序的液晶聚合物薄膜或微结构，并表征其在外界刺激下的形状演变。所提出的光制模技术具有大规模制模的能力、单次曝光和放大的可行性等优点。这项研究将产生基本的理解和新技术，以产生自折叠和扭曲的微结构和可编程的三维微/纳米制造。

As inspired by the Japanese art of paper folding, programmed origami is emerging as a new avenue towards manufacturing three-dimensional objects via autonomous folding of two-dimensional sheets of materials. To realize the programmed origami, a programmable folding mechanism at the small length scales is the key and thus in high demand. Liquid crystal polymers are weakly cross-linked polymers incorporated with rod or disk-like molecular units. When these molecular units are aligned in non-uniform directional patterns, the liquid crystal polymers can be triggered to self-deform by external stimuli such as temperature and light. This award supports fundamental research to develop the needed technology for aligning the molecular orientations in complex patterns in small length scales and to gain basic understanding on how to design molecular orientation patterns to achieve desired three-dimensional microstructures. Three-dimensional microstructures are highly desired in a variety of industrial applications such as sensors, actuators, drug delivery and photonic devices. The outcome from this research should contribute to the U.S. economy and benefit society. This multidisciplinary research provides a great opportunity to educate graduate and undergraduate students with knowledge and skills in photonics, liquid crystal science and technology, nanomanufacturing and numerical modeling, and to enhance diversity by involving minority and high-school students.Programmed origami promises manufacturing of exotic three-dimensional micro and nanostructures by self-folding of two-dimensional materials or structures. This project aims to develop capabilities to imprint folding trajectories of liquid crystal polymer films in their molecular orientation fields. It will study a novel photo-patterning technique for defining complex molecular orientation order. It will develop a basic understanding of the relationship between molecular orientation and self-folding processes. The research team will (1) design, simulate, fabricate and characterize plasmonic photomasks for desired molecular orientation patterns; (2) develop an optical exposure system for exposing photoalignment materials; and (3) design, model and fabricate liquid crystal polymer films or microstructures with embedded molecular orientational orders and characterize their shape evolution under external stimuli. The proposed photopatterning technique is advantageous in several aspects: capability of large scale patterning, single exposure and scaling-up feasibility. This research will yield both fundamental understanding and new technologies to produce self-folding and twisting microstructures and programmable three-dimensional micro/nanomanufacturing.