Surfaces, Chirality, and Liquid Crystals

摘要液晶是液晶显示器的核心，表面对液晶的排列起着重要的作用。目前，只有简单形式的对齐已被使用，这些已经足够的今天的显示。然而，未来具有更强大功能的设备将依赖于开发更复杂的表面对准。一种可能性是使用微观水平的表面图案来引入手性，或手性，到液晶的排序中。手性——你的右手不是左手的镜像这一事实——在生物和化学等许多领域都起着重要作用。事实上，许多药物必须具有特定的手性（右手或左手）才能有效。在这个项目中，首席研究员和他的团队将探索通过对液晶接触的表面进行图案化来将手性引入液晶的方法。然后，他们将研究这些系统，以确定哪些新模式会发展，这些新模式引入的力是什么，以及如何利用它们更有效地分离具有不同手性的分子，比如药物。参与这些研究的学生，从高中到研究生院，将接受最先进技术的培训，并将与来自世界各地的合作者合作。技术摘要：表面在无数系统中起着决定性的作用；对于液晶来说尤其如此。通过在纳米尺度上机械地裁剪表面结构，PI操纵相邻液晶的行为和对称性，促进新现象，应用，以及对基本物理和化学性质的更深刻理解。本项目主要研究表面施加的手性，非手性液晶中的诱导手性，以及与手性相关的力。近年来，PI开发了强大的技术，既可以利用固有的非手性材料在表面建立受控的手性，也可以在纳米尺度上成像液晶取向。他正在逐步提高这些技术，并解决手性起源于界面的最具开创性的问题。这项工作有几个目标，包括：优化机械生成的手性表面；了解表面手性对液晶对称性和锚定的影响在小至2-3微米尺度上的空间控制对映体分离；研究与手性“偶极子”有关的力；在2-3微米尺度上制造手性拓扑缺陷，包括手性缺陷，并将其用作手性纳米颗粒的陷阱；和圣杯：了解手性诱导，既有强度又有渗透深度。π吗?他的团队利用了一系列实验工具，包括但不限于光学显微镜和光学纳米层析成像（PI对近场扫描光学显微镜的改进），原子力显微镜，原子力显微镜和电子束纳米光刻，以及椭偏仪。通过利用PI的能力，从非手性材料中创建精致定制的手性衬底，并将液晶方向成像到60 x 60 x 1nm的x，y，z尺寸，这项工作正在改变我们对表面手性及其对各向异性流体的影响的概念和方法。特别是，它极大地改进了在表面上创建空间控制手性的方法，量化和理解表面诱导的非手性分子的手性，以及它在其他物理现象中的表现。这些问题跨越了多个学科，因为手性的结果出现在生物学、化学、物理学、医学和药理学中。这项研究产生了许多新的现象，并为表面手性和液晶建立了新的科学范式。

NON-TECHNICAL ABSTRACTSurfaces play an important role in aligning the liquid crystals (LC) that are the core of LC displays. Currently, only simple forms of alignment have been used and these have been adequate for today's displays. However, future devices with even greater capabilities will depend on developing more complex surface alignments. One possibility is to use surfaces patterned at the microscopic level to introduce chirality, or handedness, into the ordering of the liquid crystals. Chirality - the fact that your right hand is not a mirror image of the left - plays an important role in many areas such as biology and chemistry. In fact, many pharmaceuticals must be prepared with a specific chirality (either right or left handed) to be effective. In this project the principal investigator and his team will explore ways of introducing chirality into liquid crystals by patterning the surface they are in contact with. They will then study these systems to determine what new patterns develop, what are the forces introduced by these new patterns and how they can be used to more effectively separate molecules with different chirality, such as pharmaceuticals. The students involved in these studies, from high school to graduate school, will be trained in state-of-the-art techniques and will work with collaborators from around the world. TECHNICAL ABSTRACTSurfaces play a defining role in myriad systems; this is especially true of liquid crystals. By mechanically tailoring the surface structure on nanoscopic length scales, the PI manipulates the behavior and symmetry of the adjacent liquid crystal, facilitating new phenomena, applications, and a more profound understanding of fundamental physical and chemical properties. This project focuses on imposed chirality at the surface, induced chirality in the achiral liquid crystal, and forces associated with chirality. In recent years the PI has developed powerful techniques both to establish controlled chirality at surfaces using inherently achiral materials and to image liquid crystal orientation on nanoscopic length scales. He is ratcheting up these techniques and addressing the most seminal issues in which chirality originates at an interface. The work has several objectives, including: optimization of mechanically-generated chiral surfaces; understanding the influence of surface chirality on liquid crystal symmetry and anchoring; spatially-controlling enantiomeric segregation at scales as small as 2-3 micrometers; examining forces associated with chiral "dipoles"; creating chiral topological defects, including chiral defects, at the 2-3 micrometer scale and using them as traps for chiral nanoparticles; and the Holy Grail: understanding chiral induction, both the strength and penetration depth. The PI?s team exploits a battery of experimental tools, including - but not limited to - optical microscopy and optical nanotomography (the PI's modification of near field scanning optical microscopy), atomic force microscopy, AFM and electron beam nanolithography, and ellipsometry. By exploiting the PI's ability to create exquisitely tailored chiral substrates from achiral materials and to image liquid crystal orientation down to x,y,z dimensions of 60 x 60 x 1 nm, this work is transforming our conceptions about - and methodology toward - surface chirality and its effects on anisotropic fluids. In particular, it is leading to vastly improved methods to create spatially-controlled chirality at surfaces, the quantification and understanding of surface-induced chirality in otherwise achiral molecules, and its manifestation in other physical phenomena. These issues cut across multiple disciplines, as consequences of chirality appear throughout biology, chemistry, physics, medicine, and pharmacology. The research is giving rise to a host of novel phenomena, and establishing new scientific paradigms for surface chirality and liquid crystals.