Theoretical Approaches to Bridge Timescales in Polymer Dynamics

聚合物动力学中桥接时间尺度的理论方法

• 批准号: 0804145
• 负责人: Marina Guenza
• 金额: $ 39万
• 依托单位: University of Oregon Eugene
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-15 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0804145&HistoricalAwards=false
• 关键词: Theoretical; Approaches; Bridge; Timescales; Polymer

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.

技术摘要：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。该理论增强了根据微观分子结构和物理参数预测宏观特性的基本能力，如通过实验测量或在计算机模拟中描述的那样。该研究使用传统的平衡方法（积分方程）和非平衡统计力学。 Guenza 和同事采用一种原创方法来描述动态异构环境中一组相互作用的大分子的协作动力学，即协作动力学广义朗之万方程（CDGLE）。这是一种微观的、特定位点的平均场理论，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，以及基于分子间时间相关性的正常模式的反常弛豫，源于聚合物液体的动态非均质性质。该研究沿着三个主线或子项目展开。第一个重点是测试 CDGLE 并将其适用范围扩展到聚合度增加的聚合物液体，即跨越非缠结到缠结的转变。在第二行中，CDGLE 被修改为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，例如蛋白质。分子内势源自分子动力学计算机模拟。这项研究将建立在过去的成功基础上，该理论能够对测试蛋白 CheY 的 NMR 弛豫、X 射线德拜？沃勒温度因子和 NMR 有序参数的实验数据进行良好的定量一致性预测。针对不同蛋白质和其他实验数据进行进一步测试，以确保该方法的通用性。最后，第三个子项目扩展了 Guenza 和同事开发的粗粒程序，该程序将聚合物映射到相互作用的软胶体颗粒的集合中。此过程提供了进入 CDGLE 的有效分子间电势。该方法扩展到包括精细的分子内粗粒度和聚合物液体多尺度建模程序的开发。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特性的计算机代码。一旦经过测试，这些代码将通过一个用户友好的网站向科学界开放。该项目为 PI 提供了一个机会，让她可以像在过去的研究项目中所做的那样，继续努力吸引妇女和少数族裔参与。由于该工作的设计目的是产生现实的结果，因此与实验小组的密切合作进一步提高了项目中学生的专业经验的价值。学生还参与外展活动来宣传他们的研究。非技术摘要：该奖项支持聚合物统计和动力学特性的理论研究和教育。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来预测材料特性的基本能力，如通过实验测量或在计算机模拟中描述的那样。使用统一的聚合物动力学方法有助于全面了解聚合物运动。后者一直是聚合物物理学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）都是在液态下加工的。目标是提供一种理论工具，将化学参数（例如聚合物类型、重量、浓度和温度）的影响与整体特性（例如流动性、硬化温度）正式联系起来。开发的工具将有助于设计具有合成或生物学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特性的计算机代码。经过测试后，这些代码将通过一个用户友好的网站向科学界提供。该项目为 PI 提供了一个机会，让她可以像在过去的研究项目中所做的那样，继续努力吸引妇女和少数族裔参与。由于该工作的设计目的是产生现实的结果，因此与实验小组的密切合作进一步提高了项目中学生的专业经验的价值。学生还参与外展活动来宣传他们的研究。