CAREER: Magnetically Tunable Photonic Crystal Structures

具有可通过外部刺激调节的性质的光子材料在诸如彩色显示器、生物和化学传感器、油墨和涂料或有源光学组件等领域具有重要应用。 该提案得到了材料研究部（DMR）的固态和材料化学（SSMC）以及电子和光子材料（ETM）计划以及化学，生物工程，环境和运输系统部（CBET）的颗粒和多相过程计划的支持，旨在培养一个完整的自我，组装方法，用于构建具有光子特性的磁响应光子晶体结构，该光子晶体结构使用外部磁场快速且广泛地可调。主要策略是根据液体介质设计超顺磁性胶体构建块，使得存在强烈的颗粒间排斥力以平衡磁诱导吸引力，并最终诱导颗粒自组装成有序结构。 通过改变磁场的强度，可以快速地调节周期性，从而调节光子特性。 通过操纵磁性颗粒的表面化学，静电力、溶剂化力和空间位阻力将被用作排斥力，抵消磁感应吸引力，以实现最佳组装。 与传统的胶体组装方法不同，这种新的策略允许即时创建光子晶体结构，并在宽光谱范围内快速和完全可逆地调谐光子特性，从而为许多光子应用提供了新的平台。 该提案还探讨了使用这种自组装方法和磁性可调光子系统的应用，如全色高分辨率打印和可调光子paper.NON-TECHNICAL摘要：拟议的研究将开发一种独特的自组装方法，用于制备光子结构，其颜色可以通过施加外部磁场快速可逆地改变。 在建立排斥和吸引相互作用之间的平衡后，磁性胶体颗粒可以立即组装成具有光子特性的有序结构，这些光子特性可以通过改变磁场的强度来调节。 这些响应性光子结构将在诸如彩色显示器、生物和化学传感器、油墨和涂料或有源光学元件等领域中具有重要的应用。 拟议的研究工作将与教育推广活动密切结合，以促进学生，特别是代表性不足群体的学生对科学和工程的兴趣。 从拟议的研究结果将被纳入一个新的核心课程“纳米科学和纳米技术”提供给研究生和高年级本科生在加州大学滨江。 来自UCR和当地小型文理学院的本科生和当地高中生将被招募，并有机会通过定期的学术和暑期实习计划进行相关研究。 通过与博物馆、科学中心和教育网站的合作，将开发现场和在线展览，以广泛传播研究成果，提高公众对科学技术的理解。 在项目期间，将与UCR的研究人员、工业界、国家实验室和国际研究小组建立有效的合作关系。

TECHNICAL SUMMARYPhotonic materials with properties that can be tuned by external stimuli have important applications in areas such as color displays, biological and chemical sensors, inks and paints, or active optical components. This proposal, supported by the Solid State and Materials Chemistry (SSMC) and Electronic and Photonic Materials (EPM) programs in the Division of Materials Research (DMR) and the Particulate and Multiphase Processes program in Division of Chemical, Bioengineering, Environmental, and Transport Systems (CBET), aims to develop an integrated self-assembly approach for building magnetically responsive photonic crystal structures with photonic properties rapidly and widely tunable using external magnetic fields. The main strategy is to design the superparamagnetic colloidal building blocks in accordance to the liquid media so that a strong interparticle repulsion exists to balance the magnetically induced attraction force and eventually induce the self-assembly of particles into ordered structures. By changing the strength of the magnetic field, the periodicity and consequently the photonic property can be rapidly tuned. Through manipulation of surface chemistry of the magnetic particles, electrostatic, solvation and steric forces will be employed as repulsive forces countering the magnetically induced attractive forces for optimal assembly. Unlike conventional colloidal assembly approaches, this new strategy allows instant creation of photonic crystal structures, and rapid and fully reversible tuning of the photonic properties in a wide spectrum range, thus providing a new platform for many photonic applications. This proposal also explores the use of this self-assembly approach and the magnetically tunable photonic systems for applications such as full-color high resolution printing and rewritable photonic papers.NON-TECHNICAL SUMMARY: The proposed research will develop a unique self-assembly approach for the preparation of photonic structures whose color can be changed rapidly and reversibly by applying an external magnetic field. Upon establishing a balance between the repulsive and attractive interactions, magnetic colloidal particles can be instantly assembled into ordered structures with photonic properties that are tunable by changing the strength of the magnetic field. These responsive photonic structures will have important applications in areas such as color displays, biological and chemical sensors, inks and paints, or active optical components. The proposed research efforts will be closely integrated with educational outreach to promote the interest of students, especially those from underrepresented groups, in science and engineering. Results from the proposed research will be incorporated into a new core course "Nanoscience and Nanotechnology" offered to graduate and senior undergraduate students at the UC Riverside. Undergraduate students from UCR and local small liberal arts colleges and local high school students will be recruited and given the opportunity to conduct related research through regular academic and summer internship programs. Onsite and online exhibitions will be developed through partnerships with museums, science centers, and educational websites to broadly disseminate the research results and to enhance the public's understanding of science and technology. Effective collaborations with researchers at UCR, industry, national laboratories, and international research groups will be established during the project period.