Shaping Colloids for Self Assembly

技术摘要本项目将探索和发展颗粒形状在胶体自组装中的作用。直到最近，用于胶体自组装的基本形状一直局限于球体和棒体，这将胶体结构限制为面心立方结构、体心立方结构和一些简单的变体。胶体晶体中的原子和分子晶体无法达到所观察到的同样丰富的结构，这一点由于用钻石或类似的对称性制造光子胶体晶体的挑战而突显出来，因为这种晶体应该表现出完全的光子带隙。该项目将重点开发两种新的胶体系统：(1)锁和钥匙胶体和(2)立方体胶体。这两组胶体都代表着与现有胶体的显著背离，并导致了新的结构和新类型的相变。其目的是探索使用这些新的积木可以制造的各种结构，并开发模型来捕捉控制它们形成的基本物理。耗尽相互作用将被用作控制相互作用的强度和范围的主要手段。粒子的各向异性形状将被用来产生定向和特定的相互作用，这两种作用对于胶体科学来说都是相对较新的。一个相关的目标是开发机制，精确控制由不同材料制成的胶体的相对位置，从而增加它们制造有用新材料的潜力，包括光子晶体、催化剂和太阳能电池。这项研究将支持一名博士生在涉及物理、化学和材料科学的跨学科科学方面的教育。21世纪材料科学的中心目标是从“自下而上”制造纳米材料，而不是依赖于传统的“自上而下”的方法。因此，这个想法不是像制造计算机芯片的自上而下的方法那样，在大型物体上打上小结构的印记，而是制造自下而上自我组装成复杂的有用材料的纳米级组件。在这种自下而上的方法中，小的纳米级组件携带着组装成所需结构所需的信息。这个项目将探索纳米级物体自下而上的自组装策略，使用粒子形状作为粒子相互识别并适合更大结构设计的机制，就像拼图一样。这个挑战是双重的，因为制造复杂形状粒子的新技术将被开发出来，同时还将开发指导它们组装的设计方案。这些方法在开发光开关和电路以及太阳能电池的新材料方面应该是有用的。这个项目将支持研究生在这些先进技术方面的教育，以便在先进的科学和技术职业中取得成功。

Technical Abstract This project will explore and develop the role of particle shape in the self assembly of colloids. Until recently, the basic shapes used in colloidal self assembly have been limited to spheres and rods, which has limited colloidal structures to fcc, bcc, and a few simple variants. The inability to achieve the same richness of structures observed for atomic and molecular crystals in colloidal crystals has been brought into sharp relief by the challenge of making photonic colloidal crystals with the diamond or similar symmetries, as such crystals should exhibit full photonic band gaps. This project will focus on developing two new colloidal systems: (1) lock-and-key colloids and (2) cubic colloids. Both sets of colloids represent a significant departure from existing colloids and lead to new structures and new kinds of phase transitions. The aim is to explore the various kinds of structures that can be made using these new building blocks and to develop models that capture the basic physics controlling their formation. The depletion interaction will be used as the primary means of controlling the strength and range of the interaction. The anisotropic shapes of the particles will be exploited to generate directional and specific interactions, both of which are relatively new to colloidal science. A related goal is to develop mechanisms for precise control of the relative placement of colloids made from disparate materials, thus increasing their potential for making useful new materials, including photonic crystals, catalysts, and solar cells. The research will support the education of a PhD student in interdisciplinary science involving physics, chemistry, and materials science. Non-technical Abstract A central goal of 21st century materials science is to fabricate nanomaterials from the "bottom up" rather than relying on the traditional the "top down" approach. Thus, instead of imprinting small structures on large objects, as is typically done in top-down approaches for making computer chips, the idea is to make nanoscale components that assemble themselves from the bottom up into complex useful materials. In this bottom up approach, the small nanoscale components carry with them the information required for them to assemble into the desired structures. This project will explore strategies for bottom-up self-assembly of nanoscale objects using particle shape as the mechanism by which particles recognize each other and fit into a larger structural design, much as jigsaw puzzle pieces fit together to form a large picture. The challenge is two-fold in that new techniques to make particles with complex shapes will be developed along with design schemes for directing their assembly. These methods should be useful in developing new materials for optical switching and circuitry as well as for solar cells. This project will support the education of a graduate student in these advance techniques for careers in advanced science and technology.