Collaborative Research: Topological Defects and Dynamic Motion of Symmetry-breaking Tadpole Particles in Liquid Crystal Medium

一个快速增长的技术市场与微致动器有关：一种能够通过将一种形式的能量转化为动能来产生固体或流体机械运动的小型有源装置。它们的可编程运动能力可以影响包括传感器、药物输送和软机器人在内的几个应用。操纵微致动器在特定位置运行仍然具有挑战性。在传统的水介质中，利用纳米到微尺度的对称胶体粒子作为微致动器已经做了大量的工作。本奖项旨在合成由球形头部和高度不对称尾部特征组成的不对称蝌蚪粒子，并探索多种不对称特征对各向异性液晶介质中粒子诱导的拓扑缺陷和可控运动的影响。该项目将提供一个涉及化学、物理和工程的跨学科平台，以开发局部靶向的潜力，应用于特定细胞的药物输送和生物成像，以及通过携带催化剂启动特定位点的反应。该提案的合作性质将为来自以本科为主的大学（PUI）的本科生提供通过夏季轮转接触高强度R1机构文化的机会。拟议的外联努力还将扩大代表性不足群体的参与。该奖项将为粒子的不对称因素如何影响有序液晶（LC）介质中的拓扑缺陷、非平衡运动和可控流体动力学提供基础知识。提出的研究是确定蝌蚪粒子的不对称参数与由此产生的畸变向列场形态之间的关系。阐明这一基本知识对于合理设计化学图案表面至关重要，这些表面具有控制粒子运动的拓扑边界条件。与球形或其他对称粒子相比，蝌蚪粒子的长而灵活的尾巴可以显著增强长程有序各向异性液晶介质的不对称畸变和在界面处封装第二介质的能力，有利于粒子的推进机制和货物运输。SiO2尾部表面改性的自由度进一步增强了对颗粒运动方向和速度的操纵。通过不对称粒子合成、LC中其物理形态的实验证据和进一步的工程运动之间的反馈回路，跨学科的知识将被开发出来，将粒子设计、合成和表面化学与有序液晶介质中的拓扑缺陷和不平衡运动联系起来。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

A fast-growing technology market is related to microactuators: small-scale active devices capable of generating mechanical motion of solids or fluids by converting one form of energy into kinetic energy. Their programmable motion capabilities could influence several applications including sensors, drug delivery, and soft robotics. Manipulating microactuators to operate at a specific position is still challenging. Substantial efforts have been made on using symmetrical colloidal particles of nano- to micro-scale in conventional aqueous mediums as microacutators. This award aims to synthesize asymmetric tadpole particles composed of a spherical head and highly asymmetrical tail features and explore the impacts of multiple asymmetrical features on particle-induced topological defects and controllable motion in anisotropic liquid crystal medium. The project will provide an interdisciplinary platform involving chemistry, physics, and engineering to develop the potential for local targeting, with applications such as drug delivery and bioimaging on specific cells and initiation of site-specific reactions by carrying catalysts. The collaborative nature of this proposal will provide undergraduate students from a predominantly undergraduate institution (PUI) the opportunity to be exposed to very high intensity R1 institutional culture through summer rotations. The proposed outreach efforts will also expand the participation of underrepresented groups. This award will provide fundamental knowledge of how particles’ asymmetric factors affect topological defects, out-of-equilibrium motion, and controllable hydrodynamics in ordered liquid crystal (LC) medium. The proposed research is to determine the relationship between asymmetric parameters of tadpole particles and the morphology of the resulting distorted nematic field. Elucidating this fundamental knowledge is vital to the rational design of chemically patterned surfaces that have featured topological boundary conditions for commanding particle motion. The long and flexible tail of tadpole particles, as compared to spherical or other symmetric particles, can significantly enhance the asymmetric distortion of long-range order anisotropic liquid crystal medium and the capability to encapsulate a second media at the interface, to facilitate a propulsion mechanism for the particle and enable cargo transportation. The degree of freedom in surface modification of SiO2 tails further enhances the manipulation of direction and velocity of particle motion. Through a feedback loop between asymmetric particle synthesis, experimental evidence on its physical morphologies in LC and further engineering motion, interdisciplinary knowledge will be developed to connect the particle design, synthesis and surface chemistry to topological defects and out-of-equilibrium motion in the ordered liquid crystal media.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.