Magnetic interactions for selective assembly and reconfiguration of colloids

具有所需特性的新材料通常通过以快速、精确的方式将纳米或微米尺寸的颗粒结合在一起而形成。 这项任务已被证明是具有挑战性的，因为可用的实验方法不提供对颗粒结合和组装过程的所需控制。该项目的目标是利用外部磁场提供一种新的方法来控制水溶液中纳米和微米尺寸颗粒的组装和组织。 该项目的重点是颗粒形状，溶剂性质和施加的磁场强度对颗粒组装和结构的影响。 该项目的主要目标是建立一种快速制造微粒精确结构的实验策略，否则需要复杂的合成过程。该项目将使用组装的结构作为微米大小的车辆，用于在溶剂内的指定位置控制分子的运动和传递。聚合物结构沿着移动微粒的路径的后续形成将是一类新的聚合物印刷，其中颗粒组装体将用于控制印刷的几何形状。该项目将为本科生和研究生提供机会，在可重构材料的新兴领域发展新技能。研究小组将参与为视障和中学生举办的外展活动。 此外，调查员将与巴吞鲁日社区学院合作，向学生介绍路易斯安那州立大学提供的教育和研究机会。该项目旨在回答粒子组装中的一个基本问题：非特异性磁相互作用能否用于指导多组分胶体结构的选择性组装和重构？该项目背后的假设是，胶体颗粒周围的磁势能景观可以通过改变其形状/表面各向异性和磁化率与分散介质的对比度来设计，这可能允许客体颗粒选择性地附着到宿主微粒上的特定结合位点。本计画将借由研究铁修补胶体粒子在外磁场中的组装与重组，来验证此假说并解决上述问题。该项目旨在（1）通过设计胶体颗粒周围的磁能景观来指导组装过程，（2）确定颗粒形状对片状和非片状胶体混合物组装的影响，（3）了解外部磁场特性对组装结构重新配置的作用，以及（4）开发基于颗粒的图案化技术，使用组装的结构作为主动和自推进的子单元来驱动液相中的聚合过程。该项目将为磁场驱动的胶体组装和重新配置提供新的见解，并建立使用预组装微结构在连续介质中引导局部反应的原则。在该项目中开发的基本原理可以提供一个平台，用于快速和稳健地组装具有低对称性但受控对称性的胶体结构，这是传统胶体组装技术难以实现的。该奖项反映了NSF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。

New materials with desired properties are often formed by binding together nano- or micron-sized particles in a fast, precise fashion. This task has proven challenging because available experimental methods do not provide the desired control over the particle binding and assembly process. The goal of this project is to use external magnetic fields to provide a new way to control the assembly and organization of nano- and micron-sized particles in aqueous solution. The project focuses on effects of particle shape, solvent properties, and the strength of the applied magnetic field on assembly and structuring of the particles. The primary goal of the project is to establish an experimental strategy for rapid fabrication of precise structures of microparticles, which otherwise requires complex synthetic procedures. The project will use the assembled structures as micron-sized vehicles for controlled motion and delivery of molecules at a specified location within the solvent. The subsequent formation of a polymeric structure along the path of the moving microparticle will be a new class of polymer printing, where particle assemblies would be used to control the printed geometry. The project will provide opportunities for undergraduate and graduate students to develop new skills in the emerging field of reconfigurable materials. The research team will be involved with outreach activities for visually impaired and middle-school students. In addition, the investigator will work with Baton Rouge Community College to introduce their students to education and research opportunities available at LSU. This project seeks to answer a fundamental question in particle assembly: Can non-specific magnetic interactions be used for directing selective assembly and reconfiguration of multi-component colloidal structures? The hypothesis behind the project is that the magnetic potential energy landscape around a colloidal particle can be designed by altering its shape/surface anisotropy and magnetic susceptibility contrast with the dispersing medium, which may allow for selective attachment of a guest particle to a specific binding site on a host microparticle. The project will test the hypothesis and address the abovementioned question by examining the assembly and reconfiguration of iron patched colloidal particles in external magnetic field. The project aims to (1) Direct the assembly process by designing magnetic energy landscapes around a colloidal particle, (2) Identify the effect of particle shape on the assembly of the mixture of patchy and non-patchy colloids, (3) Understand the role of external magnetic field characteristics on the reconfiguration of the assembled structures, and (4) Develop a particle-based patterning technique using the assembled structures as active and self-propelling sub-units to drive a polymerization process in a liquid phase. The project will provide new insights into the magnetic field driven assembly and reconfiguration of colloids and establish the principles of guiding local reactions within continuous media using pre-assembled microstructures. The fundamental principles developed in the project may provide a platform for rapid and robust assembly of colloidal structures with low, but controlled symmetry, which is difficult to achieve by conventional colloidal assembly techniques.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.