CAREER: Colloidal Origami: Directing and Designing Complex Colloidal Assemblies Using Magnetic Fields

这项提议的目的是开发线性胶体链，利用自组装和定向组装将其折叠成特定的形状。这种胶体折纸将由磁性胶体链组成，这些胶体链连接在一起形成珠子弹簧珠子结构。这些链将具有明确的化学和物理性质，这些性质可以将它们折叠成特定的结构。例如，通过控制柔性链上的排斥和吸引相互作用，可以形成胶体结结构。在这些聚合物激发的胶体组件中积极探索不同的化学成分和连接性将为自组织材料提供比当前胶体组件更大的化学多样性和稳定性的可能性。将磁性胶体粒子连接到柔性链将通过利用微流控器件的层流特性来实现。这项工作的第一个目标是创建一个具有异质刚性的链。这些多链链是嵌段共聚物的胶体类似物，由磁性粒子组成，磁性粒子与不同长度的聚合物连接在一起。第二个目标是通过引入点偶极子和图案化电荷，沿着链的主干产生吸引和排斥的相互作用。这包括合成具有不同磁化率的铁磁颗粒，以及创建由铁磁颗粒和顺磁颗粒组成的链。最终的目标是理解最终形成的链结构，目的是控制这些链的折叠路径。这一提议的智力优势是开发了利用微流体流和磁场对磁性颗粒进行化学图案化时形成的新型胶体微结构。这些微观结构很有意义，因为它们赋予了有趣的材料特性；例如，通过从一种微结构切换到一种密切相关的结构，人们可能会改变材料的粘度、弹性模数和光学性质。这种组装概念的主要驱动力是创造具有折叠和自组装能力的材料，但也具有可能的化学功能的多样性。该提案中的教育计划包括将拟议的研究与当地初中生和高中生的互动结合起来。PI的实验室将接待两名女高中生参加一个在微流控设备中使用磁性胶体组装的项目。这些学生将利用这个项目参加国际可持续世界项目奥林匹克竞赛，这是一个旨在提高科学技术意识的国际科学博览会。该计划还包括以实验室演示的形式向社区推广，名为面向中学生的磁性口香糖蠕虫。国际和平研究所还将通过研究和开发新课程和座谈，让本科生和研究生参与科学学习。这包括开发一门高级课程，名为定向胶体组装，将可供化学家、物理学家和工程师使用。这项研究计划将表面科学和微流变学的方法结合在一起，创造新的胶体材料。这项拟议工作的更广泛影响是开发一个关于胶体折纸的综合研究和教学计划，通过更好地了解胶体组装并为新的粒子技术打开大门，将推动软材料领域的发展。

0955003BiswalThe aim of this proposal is to develop linear colloidal chains that fold into specific shapes using self and directed assembly. This colloidal origami will consist of chains of magnetic colloids that are linked together to form a bead spring bead structure. These chains will have welldefined chemical and physical properties that function to fold them into specific architectures. For example, by controlling the repulsive and attractive interactions along a flexible chain, a colloidal knot structure can be formed. Active exploration of diverse chemistries and connectivities in these polymer inspired colloidal assemblies will offer the potential for selforganized materials with greater chemical diversity and stability than current colloidal assemblies.Linking magnetic colloidal particles into flexible chains will be achieved by exploiting laminar flow characteristics in microfluidic devices. The first objective of this work is to create a chain with heterogeneous rigidity. These multi link chains, colloidal analogs of block copolymers, are composed of magnetic particles which have been linked together with polymers of different lengths. The second objective is to generate attractive and repulsive interactions along the backbone of a chain by introducing point dipoles and patterned charges. This includes synthesizing ferromagnetic particles with varying magnetic susceptibilities and creating chains composed of ferromagnetic and paramagnetic particles. The final objective is to understand the resulting chain structures that form with the goal of controlling the folding pathways of these chains.The intellectual merit of this proposal is the development of novel colloidal microstructures formed when magnetic particles are chemically patterned using microfluidic flows and magnetic fields. These microstructures are of great interest because they impart interesting material properties; for example, by switching from one microstructure to a closely related structure, one may alter the viscosity, elastic modulus, and optical properties of the material. This assembly concept is driven primarily by the desire to create materials that have the capacity for folding and self-assembly, but also possess the diversity of possible chemical functionalities.The educational plan in this proposal includes integrating the research proposed with interactions with local middle school and high school students. The PI's lab will host two female high school students in a project using magnetic colloidal assembly in microfluidic devices. These students will use this project to compete in the International Sustainable World Project Olympiad, an international science fair aimed at promoting awareness in science and technology. The plan also includes outreach to the community in the form of lab demos entitled Magnetic Gummy Worms for middle school children. The PI will also engage undergraduate and graduate students in scientific learning through research and the development of new curriculum and colloquia. This includes the development of an advanced level course entitled Directed Colloidal Assembly, that will be available to chemists, physicists, and engineers.This research proposal brings together methods from surface science and microfluidics to create new colloidal materials. The broader impact of this proposed work is to develop an integrated research and teaching program on colloidal origami that will advance the field of soft materials by leading to a better understanding of colloidal assembly and opening the door to new particle technologies.