Symmetry and Molecular Architecture in Liquid Crystals

在本项目中，将研究一类新的层状LC相，其中介原具有促进堆叠片层形成的侧群（由侧群分开）。各向同性、向列相和smtic - a相的层状版本出现，并有可能出现许多新现象，包括检查3D到2D交叉行为的能力。第二次逆冲包括刚性弯曲核（香蕉形）和更灵活的双介源分子在普通的灾难性液晶宿主中的混合，这可能产生双轴向列相和近晶相，并提供反斜向共斜过渡的重要信息。第三种推力涉及手性分子与界面接触并相对于界面倾斜时产生的极化；随后的极化行为与在体smtic - c *相中发现的极化行为非常不同，并提供了表面有序的有用信息。学生培训是拟议工作的重要组成部分，这将增强美国的技术基础设施。在这项资助下接受培训的学生将在IBM、摩托罗拉和罗克韦尔公司等实验室的研发工作市场上具有很强的竞争力。高度对称的物体，如球体，具有某些不太对称的物体（如弯曲的圆柱体）所不具备的物理特性，反之亦然。因此，当液晶的对称性降低时，就会出现许多令人着迷的科学现象和技术上有用的现象。例如，快速电光开关可能会出现，有无数的用途，如光学百叶窗，超高速显示和光学计算。对称性的降低也可能影响相变的性质，复杂的液晶分子可能形成新的相。提出的工作的目的是研究与减少对称性相关的新效应。首席研究员和他的学生正在利用各种复杂的实验工具，一些新的和神秘的现象将被检查和阐明。将研究三个主题：一类新的层状液晶相；溶解在普通液晶基质中的刚性和半刚性香蕉形分子的混合物；当手性分子与界面接触并相对于界面倾斜时，就会产生极化。这项工作将引导科学探索的新途径，并可能导致新技术的发展。学生培训是拟议工作的重要组成部分，一个重要的成果将是加强国家的技术基础设施，因为支持的学生将在IBM、摩托罗拉和罗克韦尔公司等实验室的研发就业市场上具有很强的竞争力

In this project, a new class of lamellar LC phases will be investigated, where the mesogens possess a side group that promotes formation of stacked lamellae (separated by the side groups). Lamellar versions of the isotropic, nematic, and smectic-A phases occur, with possibilities for many novel phenomena, including the ability to examine 3D to 2D crossover behavior. A second thrust involves mixtures of rigid bent-core (banana-shaped) and more flexible bi-mesogenic molecules in an ordinary calamitic liquid crystal host, which may give rise to biaxial nematic and smectic phases and provide important information on the anticlinic to synclinic transition. A third thrust involves polarizations that arise when a chiral molecule is in contact with, and tilted with respect to, an interface; the behavior of the ensuing polarization is very different from that found in the bulk Smectic-C* phase, and provides useful information on surface ordering. Student training is a significant component of the proposed work, which will enhance America's technological infrastructure. Students trained under this grant will be very competitive in the R&D job markets at laboratories such as IBM, Motorola, and Rockwell Corp.%%%Highly symmetric objects, such as spheres, have certain physical properties that less symmetric objects, such as curved cylinders do not have - and vice versa. Thus, when the symmetry of a liquid crystal is reduced, many scientifically fascinating and technologically useful phenomena arise. For example, fast electrooptic switching may occur, with myriad uses such as optical shutters, superfast displays, and optical computing. Reduced symmetry also may affect the nature of the phase transitions, and a complex liquid crystal molecule may form new phases. The purpose of the proposed work is to investigate new effects associated with reduced symmetry. The Principal Investigator and his students are utilizing a wide variety of sophisticated experimental tools, and several new and enigmatic phenomena will be examined and elucidated. Three topics will be studied: a new class of lamellar liquid crystalline phases; mixtures of rigid and semi-rigid banana-shaped molecules dissolved in an ordinary calamitic liquid crystal host; and polarizations that arise when a chiral molecule is in contact with, and tilted with respect to, an interface. The work will lead to new paths of scientific inquiry and may lead to the development of new technologies. Student training is a significant component of the proposed work, and an important outcome will be the enhancement of the country's technological infrastructure, as the supported students will be very competitive in the R&D job markets at labs such as IBM, Motorola, and Rockwell Corp.***