Patchy Colloids & Colloidal Molecules

摘要：本项目解决了当代材料科学的一个中心目标：在纳米尺度上创造操作和组装材料的方法。当化学家在分子尺度上解决这些问题时，设计和组装被称为“纳米颗粒”或“胶体”的小分子聚集体的方法还很不发达。这种颗粒比人类头发直径小100到10万倍，通常是球形的，表面在它们第一次接触的地方均匀地相互排斥或粘在一起。然而，为了设计有组织的有用结构，粒子不能简单地粘在它们第一次接触的地方，而是需要有“手”，只能在它们表面的特定点上，沿着特定的方向相互抓住。该项目的目标是使用新开发的纳米颗粒，这些纳米颗粒具有粘性垫或“手”，其排列方式使颗粒组合成具有技术上有用的光学、电学和机械性能的结构。这项研究可能会产生操纵光的新材料，可用于增强通信和计算的光学电路。该项目由DMR和CBET共同资助，在胶体和纳米粒子自组装和光子材料等日益重要的技术领域为学生提供丰富的多方面培训。技术摘要：本项目的目标是开发和研究两类新的非球形胶体粒子的自组装：“斑块胶体”和“胶体分子”。斑片状胶体是一种具有高度对称的定向相互作用的近球形颗粒，如在颗粒表面具有四面体对称排列的四个吸引垫的胶体球。胶体分子是由不可逆连接在一起的胶体球组成的高度对称的团簇。这些包括哑铃、三角形、四面体和八面体，以及更奇特的簇。基本动机是了解粒子形状和定向相互作用在微米级及以下自组装中的作用。一个长期的实际动机是开发胶体晶体，用于制造复杂的胶体晶体和其他结构，如光子带隙晶体。需要解决的问题包括：(1)如何操纵粒子间相互作用的方向性、强度、范围和特异性来创建新的胶体结构？(2)对称性低于球形的粒子形状如何改变凝聚相的相图？(3)外场对降低对称性粒子的影响是什么？如何利用外场来操纵和控制这些新胶体的自组装和结构？该项目由DMR和CBET共同资助，在胶体和纳米粒子自组装和光子材料等日益重要的技术领域为学生提供丰富的多方面培训。

Non-Technical Abstract: This project addresses a central goal of contemporary materials science: to create methods for manipulating and assembling materials on the nanoscale. While chemists address such problems on a molecular scale, methods for designing and assembling small molecular aggregates known as "nanoparticles" or "colloids" are poorly developed. Such particles, 100 to 100,000 times smaller than the diameter of a human hair, are usually spherical with surfaces that either uniformly repel or stick to each other where they first happen to touch. However, to design organized useful structures, particles cannot simply stick where they first touch but need to have "hands" that grab onto each other only at specific points on their surfaces and only along certain directions. The goal of this project is to use newly developed nanoparticles that have sticky pads or "hands" arranged in such a way that the particles assemble into structures that have technologically useful optical, electrical, and mechanical properties. The research could lead to new materials for manipulating light, which could be used in optical circuits for enhanced communications and computing. This project, jointly funded by DMR and CBET, also provides a rich multifaceted training for students in the increasingly technologically important areas of colloidal and nanoparticle self assembly and photonic materials. Technical Abstract:The goal of this project is to develop and study self assembly of two new classes of non-spherical colloidal particles: "patchy colloids" and "colloidal molecules." Patchy colloids are nearly spherical particles having highly symmetric directional interactions, for example colloidal spheres with four attractive pads arranged with tetrahedral symmetry on the particle surface. Colloidal molecules are high-symmetry clusters made from colloidal spheres irreversibly linked together. These include dumbbells, triangles, tetrahedra, and octahedra, as well as more exotic clusters. The fundamental motivation is to understand the role of particle shape and directional interactions for self assembly at the micron scale and below. A long-term practical motivation is to develop colloidal crystals that are useful for making complex colloidal crystals and other structures such as photonic band gap crystals. Questions to be addressed include: (1) How can directionality, strength, range, and specificity of interparticle interactions be manipulated to create new colloidal structures? (2) How do particle shapes with lower symmetry than spherical change the phase diagram of condensed phases? (3) What is the effect of external fields on particles of reduced symmetry and how can they be used to manipulate and control the self assembly and structure of these new colloids? This project, jointly funded by DMR and CBET, also provides a rich multifaceted training for students in the increasingly technologically important areas of colloidal and nanoparticle self assembly and photonic materials.