Magnetic Assembly of Deformable Colloids for Responsive Photonic Structures

在这个项目中，尹亚东教授和他在加州大学河滨分校的学生开发了新的光子结构。光子结构由比光的波长还小的粒子组成，这些粒子被人工地以有序的方式结合在一起。在这种情况下，光子结构的光学性质可以响应于机械压力或外部磁场而改变。为了构建这样的响应结构，研究小组探索了制造磁性胶体粒子的方法，这些胶体粒子在相互作用时可以改变它们的形状，然后研究这些粒子如何聚集在一起并组装成有序的结构。这些可变形的磁性胶体颗粒可以组合成不同寻常的结构，显示出传统固体颗粒无法实现的有趣的响应光学特性。该项目增强了对软胶体颗粒如何在溶液中相互作用，它们如何组装成大规模结构以及它们如何响应外部磁场的理解。该项目在技术上也很重要，因为它将使新型光学材料的制造能够对外部刺激（如磁场和机械力）产生快速而显著的光学变化。由此产生的材料可能在实际应用中有很大的用途，可能对社会产生非常积极的影响，包括新型视觉显示器，比色压力传感器和防伪装置。该项目还通过吸引K-12和本科生，特别是来自当地学校和社区学院中代表性不足的群体的学生，将研究型学习扩展到加州大学河滨分校之外。除了在加州大学河滨分校举办暑期研究体验项目外，PI还与当地社区学院的同事合作，在他们的实验室开展相关研究，以便为更多的学生提供接触前沿研究的机会。参与这项研究的学生有机会与工业合作伙伴互动，学习工作场所所需的技能。鼓励参赛高中生利用科研成果参加科学竞赛，广泛传播科研成果，促进学生对理工科的兴趣。该项目由美国国家科学基金会材料研究部固态与材料化学项目资助，加州大学河滨分校尹亚东教授和他的团队开发了可变形的超顺磁胶体粒子，用于制造新型的刺激响应光子结构。这些形状可变形的磁性胶体粒子代表了一类未开发的纳米结构材料，它们可能表现出与固体材料截然不同的组装行为。它们是构建具有不寻常结构/对称性的周期结构和固体粒子无法实现的新调谐机制的新基石。该项目的具体目标包括：1)开发合成均匀形状可变形超顺磁胶体粒子的有效方法；2)研究其在外加磁场作用下的形状变形，揭示软性胶体磁性颗粒相互作用的调控机制；3)研究了外加磁场作用下可变形胶体组装成长程有序结构的过程；4)利用形状可变形粒子制备各种类型的磁响应光子结构，表征其响应光子特性，探索宽光学调谐范围和高响应率的机会，特别是在3D晶体形式；5)在固体薄膜中制备响应光子结构并探索其防伪、比色压力传感等实际应用。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。

PART 1: NON-TECHNICAL SUMMARY In this project, Prof. Yadong Yin and his students at the University of California Riverside develop novel photonic structures. Photonic structures consist of patterns of particles, smaller than the wavelength of light, that are artificially bound together in ordered arrangements. In this case, the optical properties of the photonic structures can be changed in response to mechanical pressure or external magnetic fields. To build such responsive structures, the team explores methods for making magnetic colloidal particles that can deform their shapes when they interact with each other, and then study how these particles come together and assemble into ordered structures. These shape-deformable magnetic colloidal particles can assemble into unusual structures that display interesting responsive optical properties which cannot be achieved with conventional solid particles. This project enhances the understanding of how soft colloidal particles interact with each other in solution, how they assemble into large-scale structures, and how they respond to external magnetic fields. The project is also technologically important as it will enable the fabrication of novel optical materials with rapid and significant optical changes to external stimuli, such as magnetic fields and mechanical forces. The resulting materials may find great use in practical applications that may have a very positive impact on the society, including novel visual displays, colorimetric pressure sensors, and anti-counterfeiting devices. The project also expands research-based learning beyond the University of California Riverside campus by attracting K-12 and undergraduate students especially those from underrepresented groups from local schools and community colleges to the proposed research. Besides hosting summer research experience programs at the University of California Riverside, the PI has a partnership with colleagues in local community colleges to carry out relevant research in their laboratories in order to provide more students with opportunities to be exposed to cutting-edge research. Students involved in this research have the opportunity to interact with industrial partners to learn the skills needed in the workplace. The participating high school students are encouraged to use their research results to compete in science fairs so as to broadly disseminate the research outcomes and promote their interests in science and engineering. PART 2: TECHNICAL SUMMARY With this project, funded by the Solid State and Materials Chemistry Program in the Division of Materials Research at NSF, Prof. Yadong Yin and his group at the University of California Riverside, develop deformable superparamagnetic colloidal particles for the fabrication of novel stimuli-responsive photonic structures. These shape-deformable magnetic colloidal particles represent a class of unexplored nanostructured materials that may display very different assembly behaviors from their solid counterparts. They serve as novel building blocks for constructing periodic structures with unusual structures/symmetries and novel tuning mechanisms that cannot be achieved with solid particles. The specific aims of the project include: 1) Developing effective approaches for the synthesis of uniform shape-deformable superparamagnetic colloidal particles; 2) Studying their shape deformation in response to external magnetic fields and revealing the mechanism governing the interactions of soft colloidal magnetic particles; 3) Studying the assembly of the deformable colloids into long-range ordered structures under external magnetic fields; 4) Fabricating various types of magnetically responsive photonic structures with the shape-deformable particles, characterizing their responsive photonic properties, and exploring opportunities for broad optical tuning range and high response rate especially in the 3D crystalline form; 5) Fabricating responsive photonic structures in solid film and exploring their practical applications such as anti-counterfeiting and colorimetric pressure sensing.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.