Field-theoretic simulations with excluded volume correlations

该奖项支持理论和计算框架的发展，以理解聚合物纳米复合材料的热力学，这是一类材料，其中小的，通常是无机纳米颗粒分散在聚合物基质中。聚合物纳米复合材料被用于多种应用，从轻型保护材料到具有可调电子性能的塑料膜，然而能够准确预测其平衡结构和性能的建模技术相对较少。这项研究将有助于开发一系列新的建模技术，这些技术能够预测聚合物纳米复合材料如何在分子水平上组装。这有助于设计导电塑料材料、具有可调光学性能的聚合物和机械坚固的聚合物纳米复合材料。该奖项将支持培养分子建模技术和现代聚合物科学方面的研究生。学生们将与宾夕法尼亚大学化学系、材料科学系、化学与生物分子工程系的实验组进行互动。开发的模拟代码将向公众提供。这将促进新建模技术的广泛应用。该奖项支持为排除体积相关性变得重要的一类问题开发场理论模拟框架。在聚合物场论的传统实现中，模型的组成部分要么是点粒子，要么是具有接触排斥的无限细线。然而，在许多技术上重要的材料中，从聚合物纳米复合材料到暴露于多价离子的聚电解质，点粒子描述是无效的。这项资助的研究的目标是扩展场理论模拟框架来研究：(i)球形和各向异性纳米颗粒在聚合物基体中的分布，包括相分离的聚合物共混物和嵌段共聚物；（ii）均质接枝纳米粒子，接枝位点均匀分布在纳米粒子表面；（三）多价离子存在下的带电聚合物体系。现场理论计算结果将与基于粒子的模拟和现有的实验结果进行比较。

Nontechnical SummaryThis award supports development of a theoretical and computational framework for understanding the thermodynamics of polymer nanocomposites, a class of materials where small, typically inorganic nanoparticles are dispersed in a polymer matrix. Polymer nanocomposites are explored for a diverse set of applications ranging from lightweight protective materials to plastic membranes with tunable electronic properties, yet there are relatively few modeling techniques capable of accurately predicting their equilibrium structure and properties. This research will help with development of a family of new modeling techniques capable of predicting how polymer nanocomposites will assemble on the molecular level. This could aid in the design of conductive plastic materials, polymers with tunable optical properties, and mechanically robust polymer nanocomposites. This award will support training of graduate students in molecular modeling techniques and modern polymer science. The students will interact with experimental groups in Chemistry, Materials Science, and Chemical and Biomolecular Engineering Departments at the University of Pennsylvania. The developed simulation codes will be made publicly available. This will facilitate the broader application of new modeling techniques.Technical SummaryThis award supports the development of field theoretic simulation framework for a class of problems where excluded volume correlations become important. In traditional implementations of polymer field theory, the constituents of the model are taken as either point particles or infinitely thin threads with a contact repulsion. However, in a number of technologically important materials ranging from polymer nanocomposites to polyelectrolytes exposed to multivalent ions, a point-particle description is invalid. The goal of this funded research is to extend the field theoretic simulations framework to study: (i) the distribution of both spherical and anisotropic nanoparticles in a polymer matrix, including phase separated polymer blends and block copolymers; (ii) homogeneously grafted nanoparticles, where the grafting sites are uniformly distributed on the nanoparticle surface; and (iii) charged polymeric systems in the presence of multivalent ions. The results the field theoretical calculations will be compared with particle-based simulations and with existing experiments.