Microstructure and Properties of Inhomogeneous Polyatomic Mixtures from Density Functional Theory

CBET-0756166 Chapman许多大分子流体的现代应用都利用了它们新颖的微观结构和相行为。模拟纳米结构流体的挑战在于理解有限尺寸效应、不同维度、表面力以及多个长度和时间尺度的相互作用所产生的新物理。外部表面力的引入以及流体衬底和流体-流体相互作用之间的竞争导致了在整体系统中看不到的有趣的表面驱动相变[9]。智力优势：该项目专注于开发一种新的分子理论，用于复杂流体组件的多尺度建模，并将该理论应用于纳米结构介质中的几个关键问题。这项工作建立在PIS新的密度泛函理论(DFT)的基础上，该理论在预测非均匀多原子混合物的结构方面表现出前所未有的准确性和简单性[29，30]。对于聚合物-胶体体系和聚合物共混物涂层中的聚合物耗尽、增强和表面诱导偏析等现象，DFT的预测与分子模拟结果非常一致。此外，DFT具有与原子密度泛函理论类似的简单性和计算速度。我们建议在理论中加入多个分子缔合位置、链刚性以及亲水和疏水表面。该方法将通过分子模拟结果进行验证，并与共聚物、表面活性剂和系留聚合物体系的界面性质和结构的实验进行比较。更广泛的影响：DFT的巨大潜力导致了与Sandia国家实验室(SNL)的持续合作，将我们的DFT整合到他们的大规模并行DFT解算器包中？特拉蒙托。凭借其现有的能力，Tramonto可以在一系列2D/3D几何图形中处理生命规模的系统，如胶体和电解质。在该平台中集成PI多原子密度泛函，极大地扩展了封装的潜在范围，如聚合物-胶体聚合物-纳米颗粒体系中的自组装、嵌段共聚物膜和共混物、具有胶束或双层结构的表面活性剂或脂质体系以及聚电解质。当最终版本向公众发布时，预计这些计算工具将以适度的费用对设计或相空间(设计实验所需)进行详尽的分析，从而对纳米科学和纳米系统的设计产生重大影响。陶氏化学公司对将该理论应用于共聚溶液、共混物和表面活性剂的微观结构和界面性质建模方面有着浓厚的兴趣。桑迪亚和陶氏化学的合作意向书附有陶氏化学的直接和实物资金。对参与该项目的研究生、博士后和本科生的教育将产生进一步的影响。这些学生将向参加了我们的复杂流体联盟的公司做报告，并在国际会议上展示研究成果。这位研究生受益于陶氏化学提供的暑期实习机会。除了将新理论纳入莱斯的课程外，该项目还将利用国际公认的Connexion环境(cnx.rice.edu)开发该理论的教育模块(图书章节)，用于网络传播。

CBET-0756166ChapmanMany modern applications of macromolecular fluids take advantage of their novel microstructure and phase behavior. The challenge in modeling nano-structured fluids lies in understanding the new physics that emerges from finite-size effects, varying dimensionality, surface forces and interplay of multiple length and time scales. The introduction of external surface forces and the competition between fluid substrate and fluid-fluid interactions lead to interesting surface driven phase changes not seen in bulk systems [9]. Intellectual Merit: The project focuses on the to development of a novel molecular theory for multi-scale modeling of complex fluid assemblies and to apply the theory to several critical problems in nano-structured media. The work builds on the PIs new density functional theory (DFT) that has shown an unprecedented combination of accuracy and simplicity in predicting the structure of inhomogeneous polyatomic mixtures [29,30]. Predictions of the DFT are in excellent agreement with molecular simulation results for phenomena such as polymer depletion, enhancement and surface induced segregation key elements in polymer-colloid systems and in coatings of polymer blends. Further, the DFT has similar simplicity and computational speed to an atomic density functional theory. We propose to incorporate multiple molecular association sites, chain stiffness, and hydrophilic and hydrophobic surfaces in the theory. The approach will be validated with molecular simulation results and compared with experiment for interfacial properties and structure of copolymer, surfactant, and tethered polymer systems. Broader Impact: The immense potential of the DFT has led to an ongoing collaboration with Sandia National Laboratories (SNL) to incorporate our DFT within their massively parallel DFT solver package ? TRAMONTO. With its existing capabilities, TRAMONTO can address life-scale systems such as colloids and electrolytes in a range of 2D/3D geometries. Integrating the PIs polyatomic DFT within this platform dramatically expands the potential scope of the package to such systems as self-assembly in polymer-colloid polymer-nanoparticle systems, block copolymer films and blends, surfactant or lipid systems exhibiting micellar or bilayer structures, and polyelectrolytes. When the final version is released to the public, it is anticipated that these computational tools will have high impact on nanoscience and design of nanosystems by allowing exhaustive analysis of design or phase space (needed for design of experiments) at a moderate expense. Dow Chemical has significant interest in applying the theory to model microstructure and interfacial properties of copolymer solutions, blends, and surfactants. Letters of collaboration from Sandia and Dow are attached with direct and in-kind funding from Dow. Of further impact will be education of a graduate student, post-doc, and undergraduate students participating in the project. These students will make presentations to companies that have participated in our Consortium on Complex Fluids and present research results at international conferences. The graduate student benefited from a summer internship offered by Dow. In addition to incorporating new theory in courses at Rice, the project will develop an educational module (book chapter) of the theory for web distribution using the internationally recognized Connexions environment (cnx.rice.edu).