Static and Dynamic Properties of Polyelectrolyte Solutions

Arun Yethiraj由理论与计算化学项目的CAREER基金资助，对聚电解质溶液的静态和动态特性进行理论研究。研究了聚电解质分子在稀溶液中的构象性质与离子强度的关系。该理论的预测将首先通过一个简单模型的分子模拟来验证。然后，该理论将用于研究聚丙烯酸的化学现实模型的构象行为。为了估计聚电解质溶液中分子间相互作用的重要性，将对通过位点-位点溶剂化电位结合其余溶液的两分子体系进行模拟。这些模拟也将用于解释聚电解质溶液上的光散射实验。最后，将进行单链和双分子布朗动力学模拟，以研究粘度和自扩散系数作为离子强度的函数。Yethiraj在本科阶段的教学目标包括：1)促进课堂讨论；2)促进小组学习；3)计算机辅助教学。在研究生水平的课程中，他将介绍计算技术，从量子化学中的从头算和半经验方法到蒙特卡罗和经典系统的分子动力学模拟。聚电解质是带电的大分子。它们比中性聚合物表现出更丰富的特性，并且具有广泛的技术用途，例如：作为絮凝剂、脱水剂、破乳剂和减阻剂；作为洗涤剂和化妆品的添加剂；并用于制造膜、离子交换树脂、凝胶和改性塑料。然而，聚电解质的行为还远远没有被很好地理解，最近人们对获得对这些系统更好的分子水平理解的兴趣越来越大。Yethiraj的研究将有助于阐明这些分子特性，这些特性对于实现聚电解质系统所需的材料特性非常重要。

Arun Yethiraj is supported by a CAREER grant from the Theoretical and Computational Chemistry Program to perform theoretical studies of the static and dynamic properties of polyelectrolyte solutions. The conformational properties of the polyelectrolyte molecules in dilute solution will be investigated as a function of ionic strength. The predictions of the theory will first be tested against molecular simulations for a simple model. The theory will then be used to investigate the conformational behavior of a chemically realistic model for polyacrylic acid. Simulations of two-molecule systems that incorporate the rest of the solution via site-site solvation potentials will be performed in order to estimate the importance of intermolecular interactions in polyelectrolyte solutions. These simulations will also be used to interpret light scattering experiments on polyelectrolyte solutions. Finally, single chain and two-molecule Brownian dynamics simulations will be performed in order to investigate the viscosity and self-diffusion coefficient as a function of ionic strength. Yethiraj's teaching goals at the undergraduate level include: 1) promoting in-class discussions; 2) promoting group learning; and 3) computer aided instruction. In graduate level courses he will introduce computational techniques ranging from ab initio and semi-empirical methods in quantum chemistry to Monte Carlo and molecular dynamics simulations of classical systems. Polyelectrolytes are charged macromolecules. They display a richer variety of properties than neutral polymers, and they have a wide range of technological uses, for example: as flocculants, dewatering agents, demulsifiers, and drag reduction agents; as additives in detergents and cosmetics; and in the manufacture of membranes, ion-exchange resins, gels and modified plastics. The behavior of polyelectrolytes, however, is far from well understood, and there has recently been an increased interest in obtaining a better molecular level understanding of these systems. Yethiraj's research will help to elucidate those molecular properties which are important in achieving desired materials properties for polyelectrolyte systems.