Interactions and Self-Assembly of Particles in Complex Fluids

该奖项支持复杂流体的理论和计算研究。PI旨在结合场论和基于粒子的方法来开发可用于研究复杂流体中粒子的热力学和自组装的混合模拟工具。这些混合技术可以解释复杂流体介质中伴随颗粒分散的不同长度尺度，同时有效地结合空间和短程相互作用。提出了两类研究和工具：(1)场理论模拟(FTS)是PI最近发展起来的一种方法，将用于系统地评价不同复杂流体中任意几何形状的颗粒之间的相互作用。这些结果可能会对影响波动诱导力的不同因素产生基本的见解，特别是它们的非成对相加性质，以及能量(产生于复杂流体和粒子表面之间的物理相互作用)和熵相互作用之间的相互作用。这些研究的结果还将用于对粒子进行真空模拟，以深入了解粒子的自组装特征。(2)PI将开发一种混合多体模拟方法来模拟粒子在复杂流体中的自组装。每一步场的FTS方程和平均场方程的组合决定了刚性单元之间的有效相互作用。这些有效的相互作用将用于通过基于粒子的模拟来“进化”刚体单元。这些研究旨在阐明多体相互作用、力的非成对可加性和排除体积相互作用在调节各种复杂流体和颗粒混合物的自组装中的作用。这项研究将在聚合物-颗粒混合物、电荷稳定的胶体分散体和多嵌段棒-线圈共聚物中的相互作用和自组装的研究背景下进行。这是研究与波动、自组装和动力学有关的效应的理想模型系统。其中的每一个都可以通过调整合成条件来独立地以受控的方式进行调整。这一能力允许与实验研究进行协同交互，以比较预测和实验。在每个模型系统中，PI计划通过一个共同的目标进行研究，以识别由于空间和能量相互作用之间的竞争而产生的自组装，以及向列相/近晶相有序、结晶和微相分离之间的相互作用。这些混合模拟方法的成功实施预计将对先进材料设计的多尺度计算方法的发展产生重大影响。%该奖项支持关于复杂流体的理论和计算研究和教育。PI旨在结合不同的和强大的计算方法来开发可用于研究复杂流体中粒子的热力学和自组装的混合模拟工具。这些工具将用于研究聚合物-颗粒混合物、电荷稳定的胶体分散体和多嵌段杆-线圈聚合物中的相互作用和自组装，以阐明复杂流体物理学中的重要问题。这些模拟工具还有助于使用理论方法来预测由特定分子参数产生的先进材料的形态特征和性质。***

This award supports theoretical and computational research on complex fluids. The PI aims to combine field-theoretic and particle-based approaches to develop hybrid simulation tools that can be used to study the thermodynamics and self-assembly of particles in complex fluids. These hybrid techniques can account for the disparate length scales accompanying particle dispersions in complex fluid media, while efficiently incorporating steric and short-range interactions. Two classes of studies and tools are proposed: (1) Field-Theoretic Simulations (FTS), an approach recently developed by the PI, will be used to systematically evaluate the interactions between particles of arbitrary geometries in different complex fluids. The results may yield fundamental insights into the different factors that influence fluctuation-induced forces, in particular, their nonpairwise additive nature, as well as the interplay between energetic (arising from a physical interaction between the complex fluid and the surface of the particle) and entropic interactions. The results from these studies will also be used in effecting an in vacuo simulation of the particles, in order to glean insights into the self-assembly features of the particles. (2) The PI will develop a hybrid multibody simulation approach to the self-assembly of particles in complex fluids. A combination of FTS and mean-field equations for the fields at every step determines the effective interactions between the rigid units. These effective interactions will be used to "evolve" the rigid units through a particle-based simulation. The studies are aimed to clarify the role of multibody interactions, nonpairwise additivity of forces and excluded volume interactions in modulating the self-assembly of a variety of mixtures of complex fluids and particles. The research will be effected in the context of studies of the interactions and self-assembly in polymer-particle mixtures, charge stabilized colloidal dispersions, and multiblock rod-coil copolymers. These are ideal model systems in which to study effects pertaining to fluctuations, self-assembly, and dynamics. Each of these can be tuned independently and in a controlled way by tailoring the synthesis conditions. This capability allows for a synergistic interaction with experimental studies to compare predictions and experiments. In each of these model systems, the PI plans to carry out studies, linked by a common objective, to discern the self-assembly arising from a competition between steric and energetic interactions, as well as the interplay between nematic/smectic ordering, crystallization and microphase separation.The successful implementation of these hybrid simulation approaches is expected to have significant impact on the development of multiscale computational approaches to the design of advanced materials.%%%This award supports theoretical and computational research and education on complex fluids. The PI aims to combine distinct and powerful computational approaches to develop hybrid simulation tools that can be used to study the thermodynamics and self-assembly of particles in complex fluids. These tools will be used to study the interactions and self-assembly in polymer-particle mixtures, charge stabilized colloidal dispersions, and multiblock rod-coil polymers to elucidate important issues in the physics of complex fluids. The simulation tools also contribute to efforts to use theoretical methodology to predict the morphological characteristics and properties of advanced materials that result from specific molecular parameters. ***