Magnetic Probes of Elastic Energy, Dynamics, Interactions, and Shape Transitions of Anisotropic Colloids in Liquid Crystals

这项建议旨在通过对向列相液晶中磁性包裹体的研究，大大促进液晶中胶体领域的发展。虽然之前大多数关于向列学中胶体的研究都集中在球体上，但拟议中的实验将阐明非球体粒子的行为。与非球面粒子取向相关的额外自由度可以导致新形式的向列相介导的相互作用，产生有趣的和潜在有用的结果。通过使用高速视频显微镜和时间分辨外磁场的精确测量，将阐明这种悬浮粒子和周围的液晶基质的静态和动态性质。拟议的实验将涉及五个具体领域：(1)具有同向性锚定的孤立圆柱体的方位相关能量；(2)此类圆柱体之间的相互作用；(3)悬浮圆柱体和球体的动力学；(4)盘状夹杂物的行为；以及(5)软胶体的变形。这个项目结合了液晶物理、磁学和纳米制造的主题，将是两名研究人员的共同努力，他们拥有解决这些问题所需的互补专业知识，并有着良好的合作记录。%更广泛的影响：通过详细研究磁性粒子色调有序的机械耦合和探索新的粒子几何形状，这项工作将对基于液晶纳米复合材料的研究和技术产生潜在的重大影响。该项目的更广泛影响还将包括对物理学研究生和本科生的研究、培训和教育。为了帮助促进女性参与科学，将通过约翰·霍普金斯大学的外展计划--女性科学与工程计划(WISE)招募女高中生参与这项研究。

This proposal aims to advance substantially the field of colloids in liquid crystals through the study of magnetic inclusions in nematic liquid crystals. While most previous research on colloids in nematics has focused on spheres, the proposed experiments will elucidate the behavior of aspherical particles. The additional degrees of freedom associated with the orientation of an aspherical particle can lead to new forms of nematic-mediated interactions with interesting and potentially useful consequences. Through precision measurements employing high-speed video microscopy and time-resolved external magnetic fields, the static and dynamic properties of such suspended particles and the surrounding liquid crystal matrix will be elucidated. The proposed experiments will address five specific areas: (1) the orientation-dependent energy of isolated cylinders with homeotropic anchoring; (2) pair interactions between such cylinders; (3) the dynamics of suspended cylinders and spheres; (4) the behavior of disk-shaped inclusions; and (5) the deformations of soft colloids. This project, which combines themes in liquid crystal physics, magnetism, and nanofabrication, will be a joint effort between two investigators with the complementary expertise needed to address these problems and with a strong track record of collaboration.%%%Broader Impacts: By investigating in detail the mechanical coupling of magnetic particles tonematic order and by exploring new particle geometries, this work will have potentially significant impact on both the research on and the technology based on liquid crystalnanocomposite materials. The broader impacts of the project will also include research training and education for graduate and undergraduate students in physics. To help promote the participation of women in science, female high school students will be recruited through theWomen in Science and Engineering (WISE) Program, a Johns Hopkins University outreach initiative, to participate in the research.