Wetting and Microfluidic Flow of Liquid Crystal Droplets

液晶是一种引人入胜的材料，因为它们的特性介于简单液体和固体晶体之间。它们通常被称为物质的第四态，并因其独特的可见光调制能力而迎来了一场技术革命。随着新领域的不断出现，技术应用的潜力远未耗尽，例如基于液晶的集成芯片实验室设备、微和光流控系统以及生物传感器。在这个项目中，我们想要研究液晶液滴[1]在接近功能表面和微米级流动几何形状中的流动和润湿行为。它将在斯特拉斯克莱德大学物理系和数学与统计系的合作下进行，并使用计算方法的组合，如流体动力学的格子-玻尔兹曼方法和自由能泛函方法[2]，以及莱斯利-埃里克森框架等分析理论[3]。从液晶物理的基本观点来看，这一结果将是有趣的，但对于喷墨打印工艺也是非常相关的，这将成为下一代液晶显示器新制造方法的基石。一些关键的研究方向包括研究飞行中或悬浮液滴中的拓扑缺陷，这是当前液晶研究的一个非常活跃的领域，但完全没有探索其对流动和润湿行为的依赖。其他方向包括液滴对功能衬底的影响、缺陷的动态退火以及液滴的平衡形状和有序结构。康登斯。物质29,133003(2017年)。[2]K.Stratford，O.Henrich，J.Lintuvuori，D.Marenduzzo，M.E.Cates，胶体胆固醇复合材料的自组装：可切换光学材料的路线，NAT。通讯。5,3954(2014)。[3]P.G.de Gennes，J.Prost，《液晶物理》，牛津大学出版社，第二版(2002)。

Liquid crystals (LCs) are fascinating materials as they feature properties between those of simple liquids and solid crystals. They have been often referred to as the fourth state of matter and ushered in a technological revolution due to their unique capability of modulating visible light. The potential for technological applications is far from being exhausted as new areas emerge constantly, such as LC-based integrated lab-on-a-chip devices, micro- and optofluidic systems as well as biosensors.In this project we want to investigate the flow and wetting behaviour of liquid crystalline droplets [1] close to functional surfaces and in micrometre-sized flow geometries. It will be carried out in a collaboration between the Department of Physics and the Department of Mathematics and Statistics at the University of Strathclyde and use a combination of computational methods such as the lattice-Boltzmann method for fluid dynamics and free energy functional methods [2] and analytical theory like the Leslie-Ericksen framework [3]. The outcome will be interesting from a fundamental point of view of liquid crystal physics, but be also highly relevant for ink-jet printing processes that will form a cornerstone of new manufacturing methods for the next generation of liquid crystal displays.Some of the key research directions include the study of topological defects in droplets in flight or in suspended droplets, a very active field of current liquid crystal research, but entirely unexplored in its dependence of flow and wetting behaviour. Other directions comprise the impact of droplets on functional substrates and the in-flight annealing of defects as well as the equilibrium shape and order structure of droplets.[1] M. Urbanski, C.G. Reyes, J.H. Noh, A. Sharma, Y. Geng, V.S. Jampani and J.P. Lagerwall, J. Phys. Condens. Matter 29, 133003 (2017).[2] K. Stratford, O. Henrich, J. Lintuvuori, D. Marenduzzo, M.E. Cates, Self-Assembly of Colloid- Cholesteric Composites: A Route to Switchable Optical Materials, Nat. Comm. 5, 3954 (2014).[3] P.G. de Gennes, J. Prost, The Physics of Liquid Crystals, Oxford University Press, 2nd editon (2002).