Large-Scale and Predictable Organization of Nanocrystal Homo- and Heterojunctions through Polymer-Directed Processing

这个项目的研究目标是可扩展地制造等离子体纳米结，等离子体纳米结是在高曲率金属表面之间产生纳米尺寸的间隙，产生强烈的电磁热点。在这个项目中，金属纳米晶体将通过在纳米晶体-聚合物复合材料中进行相分离而自组织形成精确的纳米结。纳米晶体将根据形状和取向进行组装，以产生同质结(相似)和异质结(不相似)纳米晶对。分子模拟将被用来推导多组分纳米晶-聚合物混合物的全局相图，并预测大规模纳米晶组装的机理和动力学。在模拟的指导下，纳米晶体将被具有定制的链长、接枝密度和电荷的聚合物接枝进行化学修饰。对所得纳米复合材料的详细形态研究将有助于深入了解如何利用纳米晶体表面的化学性质来调节调节等离子体纳米结取向和排列的关键分子间相互作用。该项目的结果将有助于成功制造大面积、非紧密堆积的等离子体纳米晶体阵列，这些阵列目前无法通过自上而下的制造方法获得。这些纳米材料将被设计成集成到光学设备平台中，用于亚波长聚焦、表面增强拉曼光谱和电磁透明等应用。这项工作还将提供对聚合物定向纳米晶体组装的一般机制的基本理解。通过建立实验和理论之间的密切合作，这项工作有可能发现新的自组装途径和机制，以实现新的和复杂的纳米材料结构。此外，这项研究项目将有助于纳米工程领域的预科、本科生和研究生的教育。这包括为本科生设计新的实验室模块和以研究为基础的课程，以及将增加加州大学圣迭戈分校工程学本科生总体多样性的外联活动。

The research objective of this project is the scalable fabrication of plasmonic nanojunctions, the nanometer-sized gaps created between high-curvature metal surfaces that produce intense electromagnetic ?hot spots.? In this project, metal nanocrystals will be self-organized to form precise nanojunctions by carrying out phase segregation within a nanocrystal-polymer composite. Nanocrystals will be assembled with respect to shape and orientation to create homojunction (similar) and heterojunction (dissimilar) nanocrystal pairs. Molecular simulations will be used to deduce the global phase diagram of the multicomponent nanocrystal-polymer mixtures and to predict the mechanisms and kinetics of large-scale nanocrystal assembly. Guided by simulations, nanocrystals will be chemically modified by polymer grafts with tailored chain lengths, grafting density, and charge. Detailed morphology studies of the resulting nanocomposite will provide insight into how the chemical nature of the nanocrystal surface can be used to tune the key intermolecular interactions that regulate orientation and arrangement of the plasmonic nanojunctions.The results of this project will facilitate the successful fabrication of large-area, non-close-packed plasmonic nanocrystals arrays that are currently inaccessible by top-down fabrication methods. These nanomaterials will be designed for integration into optical device platforms for applications such as subwavelength focusing, surface-enhanced Raman spectroscopy, and electromagnetic transparency. This work will also provide a fundamental understanding of the general mechanisms governing polymer-directed nanocrystal assembly. By establishing a close collaboration between experiment and theory, this work has the potential for the discovery of novel self-assembly pathways and mechanisms for achieving new and complex nanomaterials architectures. In addition, this research project will contribute to the education of pre-college, undergraduate, and graduate students in the field of nanoengineering. This includes the design of new laboratory modules and research-based coursework for undergraduates as well as outreach activities that will increase the overall diversity of the undergraduate engineering population at UCSD.