CAREER: Dynamic Simulations of Reconfigurable Complex Fluids From "Janus" and "Catalytically-Driven" Colloidal Particles

这个职业发展计划结合了PI在低雷诺数流体动力学和胶体悬浮液方面的专业知识，研究基于双面Janus颗粒悬浮液的复杂流体新兴领域，双面Janus颗粒具有两个不同的侧面，这取决于它们的表面功能，可能导致新的材料特性，聚集/自定序能力，或使用远离平衡的机载化学马达进行自主行为。研究和教育活动旨在阐明可重构复杂流体的重要方面-活性材料可以在最小或不需要外部干预的情况下改变和放松其结构，使用Janus和催化驱动的胶体颗粒作为前体。研究工作分为两个主要任务。第一个重点是研究在流体流动和外力共同作用下Janus颗粒悬浮液的运动、流变学和结构组织。不同的行为取决于粒子两面之间的粒子间力（例如，硬球，吸引球，软球）。第二个研究任务旨在了解催化驱动的Janus粒子悬浮液的集体运动。基于经典的多组分扩散和耗竭絮凝理论，将采用一种简单的胶体方法通过化学反应实现自主运动。具有特定规则的简单基本动态单元和利用趋化性将被提议作为未来可重构材料的元素。这些工作将通过与合作伙伴的布朗/斯托克动力学模拟和实验来完成。该计划的教育和外联部分旨在使西班牙裔从K-12到研究生阶段的参与和教育。将开设研究生课程，研究各向异性胶体悬浮液的粒子动力学。胶体流体力学的新兴主题将被纳入现有的本科流体力学课程。模块说明自主移动的Janus粒子将开发和实现使用先进的多媒体技术。额外的教育活动包括帮助学生加强沟通技巧和改善研究生入学考试（GRE）准备的研讨会。知识价值：这项工作将提供对不对称功能化胶体粒子的基本理解，这是迄今为止缺失的，这一缺失迄今为止阻碍了Janus粒子技术的充分发展和使用-通过改进材料，传感器和药物输送。测量它们在不同颗粒浓度和流动条件下的流变行为，将为这些技术的处理和使用提供坚实的基础、基本工具和知识，从而广泛影响各向异性胶体的研究。另一方面，对Janus粒子催化驱动运动的研究将导致有趣的材料特性和行为的发现，例如通常在自然界中发现的合成趋化性和捕食者-猎物合作运动。该研究计划旨在利用布朗/斯托克动力学模拟对催化驱动的粒子运动进行必要的研究，特别是在具有挑战性的实验条件下（例如，数量集中，控制体积有限）。提出了基于催化驱动运动的简单动力学单元模型，可用于可重构复杂流体的设计和合成。更广泛的影响：该研究将对包括胶体和复杂流体、微流体和界面物理在内的几个科学技术领域产生重大影响。综合研究/教学计划将教授和培训与胶体科学和工程相关主题的代表性不足的学生。该项目的地点是波多黎各大学玛雅<s:1> ez分校（UPRM），将促进来自代表性不足群体的学生的参与和教育。该项目的教学和推广内容涉及胶体流体动力学、工程材料和运输现象。

Cordova 1055284 This CAREER development plan combines the expertise of the PI in low Reynolds number hydrodynamics and colloidal suspensions to study the emerging field of complex fluids based on suspensions of two-faced Janus particles - particles which have two distinct sides - that depending on their surface functionality could lead to novel material properties, aggregation/self-ordering abilities, or to autonomous behaviors using on-board chemical motors operating far from equilibrium. Research and educational activities are designed to elucidate important aspects of reconfigurable complex fluids - active materials that could change and relax their structure with minimum or no external intervention using as precursors Janus and catalytically-driven colloidal particles. The research efforts are divided in two main tasks. The first one focuses on studying the motion, rheology, and structural organization of Janus particle suspensions guided by a combination of fluid flows and external forces. Different behaviors are expected depending on the interparticle force between the Janus faces of the particles (e.g., hard sphere, attractive, soft). The second research task aims at understanding collective motion of catalytically-driven Janus particle suspensions. A simple colloidal approach to autonomous motion via chemical reactions will be used and implemented based on classic multicomponent diffusion and depletion flocculation theory. Simple elementary dynamic units operating with specific rules and exploiting chemotaxis will be proposed as elements for future reconfigurable materials. These efforts will be accomplished by Brownian/Stokesian dynamics simulations and experiments with collaborating partners. The education and outreach components of the plan aim to involve the participation and education of Hispanics from the K-12 to the graduate level. A graduate course in particle dynamics in anisotropic colloidal suspensions will be developed. Emerging topics in colloidal hydrodynamics will be incorporated into an existing undergraduate fluid mechanics course. Modules illustrating autonomously-moving Janus particles will be developed and implemented using advanced multimedia techniques. Additional education activities include workshops to help students strengthen their communications skills and improve their preparation for the Graduate Record Examination (GRE). Intellectual Merit: This work will provide a level of fundamental understanding of asymmetrically functionalized colloidal particles that has heretofore been missing, a lack which has thus far prevented the full development and use of Janus particle technologies - by leading to improved materials, sensors, and drug delivery. The measurement of their rheological behavior at different particle concentrations and flow conditions will broadly impact research on anisotropic colloids by providing a solid basis, basic tools, and knowledge that can be applied in the processing and use of these technologies. On the other hand, the study of catalytically-driven motion of Janus particles will lead to the discovery of interesting material properties and behaviors, such as synthetic chemotaxis and predator-prey cooperative motions that are usually found in nature. The research plan aims at providing a necessary interrogation of catalytically-driven particle motion using Brownian/Stokesian dynamics simulations, particularly at conditions challenging to address experimentally (e.g., concentrated quantities, limited control volumes). Simple models of dynamic units based on catalytically-driven motion that could be exploited for the design and synthesis of reconfigurable complex fluids are proposed. Broader Impact: The research will substantially impact several scientific and technological communities including colloids and complex fluids, microfluidics and physics of interphases. The integrated research/teaching plan will teach and train underrepresented students in topics related to colloidal sciences and engineering. The site of the project, University of Puerto Rico-Mayagüez (UPRM), will facilitate the participation and education of students from underrepresented groups. The teaching and outreach components of the project involve initiatives in colloidal hydrodynamics, engineering materials, and transport phenomena.