Phase Behavior of Colloidal Suspensions of Rods and Spheres

本研究的重点是确定棒状胶体的相行为，以及棒状和球形胶体的混合物。 棒状胶体的生物学实例包括蛋白质如肌动蛋白和微管、DNA和丝状病毒。这项工作中感兴趣的棒状胶体由基因工程丝状噬菌体fd病毒组成。球形颗粒是聚苯乙烯胶乳或水溶性聚合物如聚（环氧乙烷）。 从这些表征良好的材料中获得的知识对液晶、胶体-聚合物混合物和细胞内环境的生物物理学的基本理解以及分子有序和自组装很重要的复合材料的设计具有影响。 一个主要目标将是确定纯棒悬浮液的液晶相的基本性质，然后棒和球的混合物，不同长度的棒的混合物，以及不同直径的棒的混合物。具体而言，棒状胶体的角分布函数，共存浓度，和维里系数将得到。 这些实验旨在确定吸引力和排斥力在控制相行为中的作用，以及探索在之前的NSF资助期间在棒和球的混合物中发现的进一步丰富和意想不到的微相行为。将检查杆和球的混合物中的相变动力学，包括亚稳相的识别。最后，将研究作为示踪剂的单个棒和球的动力学。 参与研究的学生将接受跨学科培训，为他们在企业、工业和政府的各种职业生涯做好准备。%本研究的重点是确定棒状胶体和棒状和球形胶体的混合物所表现出的物质状态。棒状胶体虽然比球形胶体研究得少，但相当重要。 棒状胶体的生物学例子是蛋白质，如肌动蛋白和微管，DNA和丝状病毒。本计画所研究的棒状胶体是由基因工程改造的丝状噬菌体fd病毒所组成。对于球体，使用公知的聚苯乙烯胶乳或水溶性聚合物聚（乙烯）氧化物。所有这些胶体都是特征良好的均匀颗粒，存在一个既定的理论框架来理解它们的相行为。 了解这些特定的系统有什么影响的液晶，胶体聚合物混合物，细胞内环境的生物物理学的基本理解，以及分子有序和自组装是重要的复合材料的设计。 这项研究处于化学、生物学和物理学的交叉点。 生物分子和过程越来越多地被理解为一种机械水平，物理学在理解非平衡和无序系统方面取得了重大进展。因此，这两个领域，传统上一直被广泛分离，正在迅速向对方发展。 参加研究的学生接受跨学科的培训，这将使他们为企业，工业和政府的各种职业做好准备。

This research focuses on determining the phase behavior of rodlike colloids, and mixtures of rodlike and spherical colloids. Biological examples of rodlike colloids include proteins such as actin and microtubules, DNA, and filamentous viruses. The rodlike colloids on interest in this work consist of genetically engineered filamentous phage fd virus. The spherical particles are , either polystyrene latex or water soluble polymers such as poly(ethylene) oxide. Knowledge gained from these well characterized materials has implications for the fundamental understanding of liquid crystals, colloid-polymer mixtures, and the biophysics of the intracellular environment, as well as the design of composite materials where molecular ordering and self-assembly is important. A primary goal will be determining fundamental properties of the liquid crystalline phase of pure rod suspensions, then mixtures of rod and spheres, mixtures of rods of different lengths, and mixtures of rods of different diameters. Specifically, the angular distribution function of the rodlike colloids, co-existence concentrations, and virial coefficients will be obtained. These experiments are designed to determine the roles of attraction and repulsion in governing phase behavior, as well as to explore further rich and unexpected microphase behavior discovered in mixtures of rods and spheres during the previous NSF grant. The kinetics of phase transformation in mixtures of rods and spheres will be examined, including the identification of metastable phases. Finally, the dynamics of individual rods and spheres seen as tracers will be studied. Students participating in the research receive interdisciplinary training that will prepare them for a variety of careers in academe, industry, and government.%%%This research focuses on determining the states of matter exhibited by rodlike colloids and by mixtures of rodlike and spherical colloids. Rodlike colloids, though less studied than spherical colloids, are of considerable importance. Biological examples of rodlike colloids being proteins such as actin and microtubules, DNA, and filamentous viruses. The rodlike colloids studied in this project consist of genetically engineered filamentous phage fd virus. For spheres, the well known polystyrene latex or water soluble polymer poly(ethylene) oxide are employed. All these colloids are well characterized, uniform particles for which an established theoretical framework exists for understanding their phase behavior. What is learned about these particular systems has implications for the fundamental understanding of liquid crystals, colloid-polymer mixtures, the biophysics of the intracellular environment, as well as the design of composite materials where molecular ordering and self-assembly is important. This research lies at the intersection of chemistry, biology, and physics. Biological molecules and processes are increasingly being understood at a mechanistic level, and physics is making significant gains in understanding non-equilibrium and disordered systems. Thus these two fields, which traditionally have been widely separated, are swiftly growing towards each other. Students participating in the research receive interdisciplinary training that will prepare them for a variety of careers in academe, industry, and government.