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.
