SGER: Structure and Phase Behavior of Charged and Polymer-Containing Colloidal Dispersions

胶体分散体在光子晶体、催化剂、膜、多孔电极和高级陶瓷等现代材料的制造中有着广泛的应用。这些应用需要理论指导来理解界面和热力学现象，如胶体稳定性、结构性质和相行为，这些现象取决于多个参数，包括粒径和浓度、电荷密度、离子强度、溶剂和溶解聚合物的性质以及围合几何形状。为了满足这一要求，本研究将统计力学的理论方法与小角中子散射（SANS）实验相结合，建立了统一的分子框架，用于定量描述带电和含聚合物胶体体系的结构和热力学性质。本探索性研究项目包括四个主要部分：1)胶体分散体微观结构的密度泛函理论；2)计算对和多体胶体力和胶体结构，重点计算含多价盐离子和聚合物的胶体；3)计算胶相行为，包括结构有序和亚稳流体-流体平衡；4)聚n -异丙基丙烯酰胺（PNIPAM）分散体实验，对计算结果进行校准。本探索性研究选择热响应型PNIPAM分散体，因为通过调整制备条件和水溶液的组成，可以很容易地控制颗粒的物理化学性质和胶体力。利用小角中子散射（SANS）和传统的静态光散射（SLS）和动态光散射（DLS）测量，研究了带电和含聚合物PNIPAM分散体的胶体相图、结构因子、离子分布、渗透第二维里系数和粒径分布。本探索性研究将新的理论方法与SANS协同结合，以表征复杂系统的界面结构和热力学性质，具有重要的智力价值。在这项工作中建立的分子模型将在软凝聚态物质的许多其他应用中，为在使用亚微米构建块制造新一代纳米结构材料期间选择溶液条件提供理论指导。更广泛的影响这个SGER研究项目可以导致一些广泛的影响。首先，这项工作的结果将为在相关领域工作的本科生和研究生感兴趣的胶体自组装理论和实验的新课程提供必要的基础。在这一领域接受培训的学生将非常有市场，并将能够在纳米技术领域追求高生产力的职业。其次，这项工作将为来自加州大学河滨分校的社会经济弱势学生提供支持，帮助他们参与研究，并获得理论建模和前沿实验技术（如中子散射）的跨学科技能。最后，这项探索性工作所产生的出版物将对与界面材料相关的基础研究和技术应用产生重大影响。

Wu, JianzhongU of Cal - Riverside "SGER: Structure and Phase Behavior of Charged Polymer-Containing Colloidal Dispersions"Colloidal dispersions are broadly applied in the fabrication of modern materials such as photonic crystals, catalysts, membranes, porous electrodes, and advanced ceramics. These applications require theoretical guidelines for understanding interfacial and thermodynamic phenomena such as colloidal stability, structural properties, and phase behavior that depend on multiple parameters, including particle size and concentration, charge density, ionic strength, properties of solvent and dissolved polymers, and confining geometry. To meet this requirement, the present research combines theoretical methods from statistical mechanics with small angle neutron scattering (SANS) experiments to establish a unified molecular framework for quantitative description of structural and thermodynamic properties of charged and polymer-containing colloidal systems. This exploratory research project consists of four major components: 1) a density functional theory for the microscopic structures of colloidal dispersions; 2) calculating pair and multibody colloidal forces and colloidal structure with an emphasis on those containing multivalent salt ions and polymers; 3) calculating colloidal phase behavior including structural ordering and metastable fluid-fluid equilibrium; 4) Experiments on poly-N-isopropylacrylamide (PNIPAM) dispersions for the calibration of calculated results. Thermally responsive PNIPAM dispersion is selected in this exploratory research because the physiochemical properties of the particles and the colloidal forces can be easily controlled by tuning the preparation conditions and the composition of the aqueous solution. The colloidal phase diagrams, structure factors, ionic distributions, osmotic second virial coefficients, and particle size distributions of charged as well as polymer-containing PNIPAM dispersions will be studied using small-angle neutron scattering (SANS) and conventional static and dynamic light scattering (SLS and DLS) measurements.Intellectual MeritsThis exploratory research holds significant intellectual merits for its synergetic combination of novel theoretical approaches with SANS to represent the interfacial structural and thermodynamic properties of complex systems. The molecular models developed in this work will be useful, among numerous other applications of soft condensed matter, for developing theoretical guidelines in the selection of solution conditions during the fabrication of a new generation of nanostructured materials using submicron building blocks.Broader ImpactsThis SGER research project can lead to a number of broad impacts. First, results from this work will provide the essential basis for new courses on theory and experiment of colloidal self-assembly that will be of interest to both undergraduate and graduate students working in related fields. Students trained in this area will be highly marketable and will be able to pursue highly productive careers in nanotechnology. Second, this work will provide support for socioeconomically disadvantaged students from the University of California at Riverside to participate in research and gain interdisciplinary skills in theoretical modeling and cutting edge experimental techniques such as neutron scattering. Finally, the publications resulting from this exploratory work will have significant impacts on both fundamental research and technological applications related to materials at the interface.