Thermodynamics and Hydrodynamics of Anisotropic Colloids

该奖项支持计算和理论研究和教育，以开发大大加速和增强的各向异性胶体悬浮液的模拟方法。具有各向异性相互作用的胶体，即具有非球形和/或非均匀表面化学性质的颗粒的制造取得了重大进展。这类研究的目标之一是通过操纵构建块来控制自组装材料的结构。然而，事实证明很难将单个胶体的性质与所产生的聚集体的结构联系起来。计算机模拟能够指导和解释实验工作，但目前几乎只处理理想化的单分散系统。从实验的角度来看，很明显，设计复杂结构的重要途径是多种组件的组合，而不是使用单一的高度复杂的建筑模块。PI的目标是通过新的计算方法来弥补这一差距，这种方法可以跨越当前算法无法达到的大范围的时间和长度尺度。这项工作的重点将是开发一类新的高效簇蒙特卡罗算法，并扩展和应用悬浮胶体流体动力学的模拟方法。当前建模工作的第二个缺点是忽略了溶剂的动力学效应。“斑驳”的相互作用会导致粒子保持在非平衡状态，而流体动力学的相互作用决定了粒子相遇的路径。PI计划将包含流体动力学的最新技术扩展到包含具有各向异性边界条件和相互作用的胶体的系统。这两项进展将为各向异性胶体多组分系统的流体力学和热力学建模提供一个全面的框架。这个框架将被用来获得物理见解，并与实验建立直接联系。PI将继续与实验人员密切合作。本研究中开发的模拟方法将通过促进广泛类别的复杂流体的计算研究，从软凝聚态系统到生物相关解决方案，产生超出本计划范围的影响。聚类算法现在经常被纳入PI教授给不同背景的本科生的模拟课程中，为课堂带来了新的方法。PI已经启动并将继续开展一项强有力的教育推广计划，包括向追求高中文凭的成年学生教授基础科学课程，并向伊利诺伊州帕拉蒂尼的哈珀学院（Harper College）的第二次机会学生教授热力学入门课程。该奖项支持计算和理论研究和教育，以开发大大加速和增强的模拟方法，用于悬浮在流体中的各种形状的颗粒。这些材料系统，或胶体，可以用来制造具有新特性的材料，从比人类头发直径小一万倍或更多的积木颗粒开始。由于粒子在流体中相互作用的方式，它们可以自己组装成一种材料。实验学家试图设计构建模块和流体环境，以获得具有所需性能的材料。计算机模拟有望指导和可能设计基于这种方法的材料。到目前为止，计算机模拟主要集中在球形粒子上。PI的目标是开发新的模拟技术，以适应不同形状的粒子。粒子的形状是由它的几何形状和它与其他粒子相互作用的性质控制的。模拟方法还将包括悬浮颗粒所在的流体。PI还旨在克服对模拟方法的需求，这些方法可以适当地包括在大范围的长度和时间尺度上发生的过程。这项工作将在实验人员的密切配合下进行。这是通过计算来理解粒子在溶液中如何组织的基础研究。它有助于更广泛地利用这些知识来开发新的方法来制造具有新特性的材料，并使用计算来实现有目的的设计。这种能力的实现将对美国的竞争力产生重大影响。本研究中开发的模拟方法将对其他学科，特别是化学和生物学中其他复杂流体的计算研究产生影响。PI将继续将在这项研究过程中开发的算法纳入他教授给不同背景的本科生的模拟课程中。PI已经启动并将继续开展一项强有力的教育推广计划，包括向追求高中文凭的成年学生教授基础科学课程，并向伊利诺伊州帕拉廷市哈珀学院（Harper College）的第二次机会学生教授热力学入门课程。

TECHNICAL SUMMARY This award supports computational and theoretical research and education to develop greatly accelerated and enhanced simulation methods for suspensions of anisotropic colloids.Significant progress has been made in the fabrication of colloids with anisotropic interactions, that is, particles with aspherical shapes and/or inhomogeneous surface chemistry. One of the goals of such research is to control the structure of self-assembled materials through manipulation of the building blocks. However, it has proven difficult to correlate the nature of individual colloids with the structure of the resulting aggregates. Computer simulations are able to guide and interpret experimental work, but currently deal almost exclusively with idealized, monodisperse systems. From the experimental perspective, it has become clear that an important route towards the design of complex structures arises from the combination of multiple components, rather than from the use of a single highly complicated type of building block. The PI aims to bridge this gap by means of new computational methods that can span a wide range of time and length scales that are inaccessible to current algorithms. A focus of this work will be on developing a new class of highly efficient cluster Monte Carlo algorithms and to extend and apply simulation methods for the hydrodynamics of colloids in suspension. A second shortcoming of current modeling efforts is the neglect of kinetic effects due to the solvent. "Patchy" interactions can cause particles to remain trapped in nonequilibrium states, and hydrodynamic interactions determine the pathways along which particles encounter each other. The PI plans to extend recent techniques for the inclusion of hydrodynamics to systems containing colloids with anisotropic boundary conditions and interactions. Jointly, these two developments would provide a comprehensive framework for the modeling of hydrodynamics and thermodynamics of multicomponent systems of anisotropic colloids. This framework will be exploited to gain physical insights and make direct connections to experiments. The PI will continue to work in close collaboration with experimentalists.The simulation methods developed in this research will have an impact beyond the scope of this program by facilitating the computational study of broad classes of complex fluids, ranging from soft condensed-matter systems to biologically relevant solutions. Cluster algorithms are now routinely incorporated in the simulation course taught by the PI to undergraduates of various backgrounds, bringing new methods to the classroom. The PI has initiated and will continue a strong educational outreach program involving teaching basic science classes to adult students pursuing a high-school diploma and introductory thermodynamics to second-chance students at Harper College, a community college in Palatine, Illinois.NONTECHNICAL SUMMARYThis award supports computational and theoretical research and education to develop greatly accelerated and enhanced simulation methods for particles of various shapes suspended in fluids. These materials systems, or colloids, can be used to fabricate materials with novel properties starting from building block particles that are some ten thousand or more times smaller than the diameter of a human hair. Because of the way the particles interact in the fluid, they can assemble themselves into a material. Experimentalists seek to engineer the building blocks and the fluid environment to achieve a material with desired properties. Computer simulations hold promise to guide and possibly design materials based on this method. So far, computer simulations have largely focused on spherical particles. The PI aims to develop new simulation techniques that can accommodate particles of different shapes. The shape of the particle is controlled by its geometry and the nature of its interactions with other particles. The simulation methods will also include the fluid in which the particles are suspended. The PI also aims to overcome the need for simulation methods that can properly include processes that occur over a wide range of length and time scales. The work will be carried out in close connection with experimentalists.This is fundamental research to understand through computation how particles organize themselves in solution. It contributes to the broader effort of exploiting this knowledge to develop new ways to fabricate materials with novel properties and using computation to enable their purposeful design. The realization of this capability would have a significant impact on American competitiveness. The simulation methods developed in this research will have an impact on the computational study of other complex fluids in other disciplines, notably chemistry and biology. The PI will continue to incorporate algorithms developed in the course of this research into the simulation course that he teaches to undergraduates of various backgrounds. The PI has initiated, and will continue, a strong educational outreach program involving teaching basic science classes to adult students pursuing a high-school diploma and introductory thermodynamics to second-chance students at Harper College, a community college in Palatine, Illinois.