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，棒状胶体和球形胶体的混合物。棒状胶体的生物学例子包括肌动蛋白、微管、DNA和丝状病毒等蛋白质。本研究关注的棒状胶体由基因工程的丝状噬菌体fd病毒组成。球形颗粒是聚苯乙烯乳胶或水溶性聚合物，如聚（乙烯）氧化物。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复合材料的设计具有重要意义，其中分子有序和自组装是重要的。主要目标将是确定纯棒悬浮液的液晶相的基本性质，然后是棒和球的混合物，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，将得到棒状胶体的角分布函数、共存浓度和维里系数。这些实验旨在确定吸引和排斥在控制相行为中的作用，以及探索在之前的NSF资助期间在棒和球体混合物中发现的进一步丰富和意想不到的微相行为。在棒和球的混合物相转变的动力学将被检查，包括亚稳相的识别。最后，将研究作为示踪剂的单个棒和球体的动力学。参与研究的学生将接受跨学科的培训，为他们在学术界、工业界和政府的各种职业生涯做好准备。这项研究的重点是确定棒状胶体以及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，但却相当重要。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。本课题研究的棒状胶体由基因工程的丝状噬菌体fd病毒组成。对于球，众所周知的聚苯乙烯乳胶或水溶性聚合物聚（乙烯）氧化物被采用。所有这些胶体都具有良好的特征，均匀的颗粒，并且存在一个建立的理论框架来理解它们的相行为。对这些特殊系统的了解对液晶、胶体-聚合物混合物、细胞内环境的生物物理学以及复合材料的设计具有重要意义，其中分子有序和自组装是重要的。这项研究是化学、生物学和物理学的交叉研究。生物分子和过程越来越多地在机械水平上被理解，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，这两个传统上被广泛分开的领域正在迅速地相互发展。参与研究的学生将接受跨学科的培训，为他们在学术界、工业界和政府的各种职业生涯做好准备。

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.