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

本研究旨在通过对向列液晶中磁性包裹体的研究，使液晶中胶体的研究取得实质性的进展。虽然以往对向列数学中胶体的研究大多集中在球体上，但提出的实验将阐明非球面颗粒的行为。与非球面粒子方向相关的额外自由度可以导致新形式的向列介导的相互作用，具有有趣和潜在有用的结果。通过高速视频显微镜和时间分辨外磁场的精密测量，将阐明这些悬浮颗粒及其周围液晶基质的静态和动态特性。提出的实验将解决五个具体领域：(1)具有各向同性锚固的孤立圆柱体的方向依赖能量；(2)气缸间的副相互作用；(3)悬浮圆柱体和球体的动力学；(4)盘状夹杂物的行为；(5)软胶体的变形。该项目结合了液晶物理、磁学和纳米制造的主题，将由两位研究人员共同努力，他们具有解决这些问题所需的互补专业知识，并具有良好的合作记录。更广泛的影响：通过详细研究磁性颗粒音阶的机械耦合和探索新的颗粒几何形状，这项工作将对液晶纳米复合材料的研究和基于液晶纳米复合材料的技术产生潜在的重大影响。该项目更广泛的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。为了促进女性在科学领域的参与，将通过约翰霍普金斯大学的外展倡议“科学与工程领域的女性”（WISE）计划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.