Surfaces, Chirality, and Liquid Crystals

非技术表面在对准液晶显示器的核心液晶(LC)方面起着重要作用。目前，只使用了简单的对准形式，对于今天的显示器来说已经足够了。然而，拥有更大能力的未来设备将取决于开发更复杂的表面对齐。一种可能性是使用在微观水平上形成图案的表面，在液晶的有序性中引入手性或手性。手性--你的右手不是左手的镜像--在生物和化学等许多领域都扮演着重要的角色。事实上，许多药物必须具有特定的手性(无论是右手还是左手)才能有效。在这个项目中，首席研究人员和他的团队将探索通过对他们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，以确定产生什么新模式，这些新模式引入的力是什么，以及如何使用它们更有效地分离具有不同手性的分子，如药物。参与这些研究的学生，从高中到研究生，将接受最先进的技术培训，并将与来自世界各地的合作者合作。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剪裁表面结构，PI操纵相邻液晶的行为和对称性，促进新的现象、应用和对基本物理和化学性质的更深刻的理解。本项目的重点是表面的外加手性，非手性液晶中的诱导手性，以及与手性相关的力。近年来，PI发展了强大的技术，既可以利用固有的非手性材料在表面建立可控的手性，又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，并解决最具开创性的问题，即手性起源于界面。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；在小到2-3微米的尺度上空间控制对映体分离；检查与手性“偶极”相关的力；在2-3微米尺度产生手性拓扑缺陷，包括手性缺陷，并将其用作手性纳米颗粒的陷阱；以及圣杯：理解手性诱导，包括强度和渗透深度。S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(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测量。通过利用PI的能力，从非手性材料创建精致定制的手性衬底，并将液晶取向成像到60 x 60 x 1 nm的x、y、z维度，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，它正在极大地改进在表面创建空间控制的手性的方法，量化和理解其他非手性分子中的表面诱导手性，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，因为手性的后果出现在生物学、化学、物理学、医学和药理学中。这项研究正在产生许多新的现象，并建立了关于表面手性和液晶的新的科学范式。

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.