Theoretical Approaches to Bridge Timescales in Polymer Dynamics

技术概述：该奖项支持聚合物统计和动态特性方面的理论研究和教育。这项工作得到了化学部和材料研究部的支持。该理论增强了基于微观分子结构和物理参数，通过实验测量或计算机模拟来预测宏观性质的基本能力。研究采用传统的平衡（积分方程）和非平衡统计力学方法。Guenza等人采用了一种新颖的方法来描述一组相互作用的大分子在动态异构环境中的合作动力学，即合作动力学广义朗格万方程（CDGLE）。这是一种微观的、特定位置的平均场理论，它成功地解释了实验观察到的聚合物熔体中质心的异常扩散，以及基于分子间时间相关的正常模式的异常弛豫，这源于聚合物液体的动态非均质性。研究沿着三条主线或子项目发展。第一个重点是测试CDGLE，并将其适用范围扩展到聚合程度增加的聚合物液体中，即跨越非纠缠到纠缠的转变。在第二行中，对CDGLE进行了修改，以描述稀溶液中的聚合物动力学，包括具有生物学意义的聚合物，如蛋白质。分子内电位是由分子动力学计算机模拟得到的。这项研究将以过去的成功为基础，在过去的成功中，该理论已经能够做出与核磁共振弛豫、x射线德拜？实验蛋白CheY的壁温因子和核磁共振序参量。对不同的蛋白质和其他实验数据进行进一步的测试，以确保该方法的普遍性。最后，第三个子项目扩展了由Guenza及其同事开发的粗粒化程序，该程序将聚合物映射为相互作用的软胶体颗粒集合。这个过程提供了进入CDGLE的有效的分子间电位。该方法扩展到包括精细的分子内粗粒化和聚合物液体多尺度建模程序的开发。这个项目的影响超出了研究本身。这个项目的发展产生了预测这些聚合物性质的计算机代码。经过测试后，这些代码将通过一个用户友好的网站提供给科学界。该项目是PI继续努力吸引妇女和少数民族的机会，就像她在过去的研究项目中所做的那样。由于这项工作是为了产生现实的结果而设计的，因此与实验小组的密切合作进一步提高了学生在项目中的专业经验的价值。学生们还参与了宣传他们的研究的外展活动。非技术总结：该奖项支持聚合物统计和动力学特性方面的理论研究和教育。这项工作得到了化学部和材料研究部的支持。该理论增强了根据组成聚合物分子的分子结构和物理参数，通过实验测量或计算机模拟来预测材料性能的基本能力。使用统一的方法来聚合物动力学有助于发展对聚合物运动的全面理解。后者一直是聚合物物理实践和基础兴趣的长期目标，因为所有的聚合物材料（纤维，塑料，涂层材料等）都是在液态下加工的。其目标是提供一种理论工具，将化学参数（如聚合物类型、重量、浓度和温度）与整体特性（如易流动性、硬化温度）的影响正式联系起来。开发的工具将有助于设计具有合成或生物意义的定制聚合材料。这个项目的影响超出了研究本身。这个项目的发展产生了预测这些聚合物性质的计算机代码。经过测试后，这些代码将通过一个用户友好的网站提供给科学界。该项目是PI继续努力吸引妇女和少数民族的机会，就像她在过去的研究项目中所做的那样。由于这项工作是为了产生现实的结果而设计的，因此与实验小组的密切合作进一步提高了学生在项目中的专业经验的价值。学生们还参与了宣传他们的研究的外展活动。

TECHNICAL SUMMARY:This award supports theoretical research and education in statistical and dynamical properties of polymers. The work is supported by the Division of Chemistry and the Division of Materials Research. The theory enhances the basic ability to predict macroscopic properties, as measured experimentally or described in computer simulations, based on the microscopic molecular structure and physical parameters. The research uses traditional methods of equilibrium (integral equations) and non-equilibrium statistical mechanics. Guenza and coworkers employ an original approach to describe the cooperative dynamics of a group of interacting macromolecules in dynamically heterogeneous environments, i.e. the Cooperative Dynamics Generalized Langevin Equation (CDGLE). This is a microscopic, site-specific, mean-field theory, which has successfully explained the experimentally observed center-of-mass anomalous diffusion in polymer melts, and the anomalous relaxation of their normal modes, on the basis of intermolecular time-dependent correlation, originated from the dynamically heterogeneous nature of polymer liquids.The research develops along three main lines or subprojects. The first focuses on testing CDGLE and extending its range of applicability to liquid of polymers with increasing degree of polymerization, i.e. across the unentangled-to-entangled transition. In the second line, CDGLE is modified to describe polymer dynamics in dilute solutions, including polymers of biological significance such as proteins. Intramolecular potentials are derived from molecular dynamics computer simulations. This research will build on past success where the theory has been able to make predictions in good quantitative agreement with experimental data of NMR relaxation, X-ray Debye?Waller temperature factors and NMR order-parameters for the test protein CheY. Further testing against different proteins and other experimental data is undertaken to ensure the generality of the approach. Finally, the third subproject extends the coarse-graining procedure, developed by Guenza and coworkers, which maps polymers into collections of interacting soft-colloidal particles. This procedure provides the effective intermolecular potential entering CDGLE. The approach is extended to include a refined intramolecular coarse-graining and the development of a procedure for multiscale modeling of polymer liquids. The impact of the project extends beyond the research. The development of this project produces computer codes which predict these polymer properties. Once tested, the codes will be available to the scientific community through a user-friendly website. The project is an opportunity for the PI to continue her efforts to engage women and minorities as she has done in past research projects. Because the work is design to have realistic consequences, there are close collaborations with experimental groups which further enhances the value of the professional experience for the students in the project. Students are also involved in outreach activities to publicize their research.NONTECHNICAL SUMMARY:This award supports theoretical research and education in statistical and dynamical properties of polymers. The work is supported by the Division of Chemistry and the Division of Materials Research. The theory enhances the basic ability to predict material properties, as measured experimentally or described in computer simulations, based on the molecular structure and physical parameters of constituent polymer molecules. The use of a unified approach to polymer dynamics aids in developing a comprehensive understanding of polymer motion. The latter has been a long-standing goal of both practical and fundamental interest in polymer physics, since all polymeric materials (fibers, plastics, coating materials, etc.) are processed in their liquid state. The goal is to provide a theoretical tool that formally connects the effect of chemical parameters (e.g., polymer type, weight, concentration, and temperature) to the global properties (e.g., ease of flow, hardening temperature). The tools developed will be useful in designing custom-tailored polymeric materials of synthetic or biological significance.The impact of the project extends beyond the research. The development of this project produces computer codes which predict these polymer properties. Once tested, the codes will be made available to the scientific community through a user-friendly website. The project is an opportunity for the PI to continue her efforts to engage women and minorities as she has done in past research projects. Because the work is design to have realistic consequences, there are close collaborations with experimental groups which further enhances the value of the professional experience for the students in the project. Students are also involved in outreach activities to publicize their research.