Theoretical Approaches to Bridge Timescales in Polymer Dynamics

该奖项支持聚合物统计和动力学性质的理论研究和教育。这项工作得到了化学部和材料研究部的支持。该理论增强了预测宏观性质的基本能力，如实验测量或计算机模拟中描述的，基于微观分子结构和物理参数。研究使用传统的平衡方法（积分方程）和非平衡统计力学。Guenza及其同事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质环境中的合作动力学，即合作动力学广义朗之万方程（CDGLE）。这是一个微观的、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的质心反常扩散，以及它们的正常模式的反常弛豫，基于分子间的时间相关，起源于聚合物液体的动态非均匀性。第一个重点是测试CDGLE和扩大其适用范围的液体聚合物与聚合度的增加，即跨越解开纠缠到纠缠的过渡。在第二行中，CDGLE被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。分子内势能是由分子动力学计算机模拟得到的。这项研究将建立在过去的成功，理论已经能够作出预测，在良好的定量协议与实验数据的核磁共振弛豫，X射线德拜？测试蛋白CheY的Waller温度因子和NMR阶参数。对不同的蛋白质和其他实验数据进行进一步的测试，以确保该方法的通用性。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的集合。该过程提供了进入CDGLE的有效分子间势。该方法扩展到包括一个精致的分子内粗粒化和多尺度建模的聚合物液体的程序的发展。该项目的影响超出了研究范围。该项目的开发产生了预测这些聚合物性能的计算机代码。这些守则经测试后，将通过一个方便用户的网站提供给科学界。该项目是PI继续努力让妇女和少数民族参与的机会，就像她在过去的研究项目中所做的那样。由于这项工作的目的是有现实的后果，有密切的合作与实验组，进一步提高了专业经验的学生在项目中的价值。学生们还参与宣传他们的研究的推广活动。非技术性总结：该奖项支持聚合物统计和动力学性质的理论研究和教育。这项工作得到了化学部和材料研究部的支持。 该理论增强了基于组成聚合物分子的分子结构和物理参数预测材料性质的基本能力，如实验测量或计算机模拟中描述的。聚合物动力学的统一方法的使用有助于发展聚合物运动的全面理解。后者一直是聚合物物理学中的实际和基本兴趣的长期目标，因为所有聚合物材料（纤维、塑料、涂层材料等）都可以在聚合物物理学中应用。都是在液态下加工的我们的目标是提供一个理论工具，正式连接化学参数的影响（例如，聚合物类型、重量、浓度和温度）与整体性能（例如，易流动性、硬化温度）。开发的工具将用于设计具有合成或生物意义的定制聚合物材料。该项目的影响超出了研究范围。该项目的开发产生了预测这些聚合物性能的计算机代码。这些守则经测试后，将通过一个方便用户的网站提供给科学界。该项目是PI继续努力让妇女和少数民族参与的机会，就像她在过去的研究项目中所做的那样。由于这项工作的目的是有现实的后果，有密切的合作与实验组，进一步提高了专业经验的学生在项目中的价值。学生们还参与宣传其研究的外联活动。

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.