Statistical Mechanics of Semiflexible Polymers

半柔性聚合物的统计力学

• 批准号: 9970589
• 负责人: Zhen-Gang Wang
• 金额: $ 20.7万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-05-01 至 2003-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9970589&HistoricalAwards=false
• 关键词: Statistical; Mechanics; Semiflexible; Polymers

9970589WangThis grant supports theoretical research on the statistical mechanics of polymers. The use of flexible chain models for polymers, e.g., the freely-jointed chain model, the bead-string or its continuous version of the gaussian model, have contributed considerably to our current understanding of the dynamic and thermodynamic properties of polymers. Many polymer systems, especially biopolymers such as DNA and actin filaments, and main-chain liquid-crystalline polymers, require that the stiffness of the polymer chain be taken into account explicitly. A number of fundamental issues will be addressed in the static and dynamic properties of semiflexible polymers. These include: (1) understanding the single chain dynamics of a semiflexible polymer; (2) understanding the conformation and dynamics of a semiflexible chain in a nematic field, with a focus on multiple hairpins; and, (3) understanding the phase behavior, fluctuations and instabilities in nematic semiflexible polymer solutions. While the main focus of this work is understanding of the fundamental physics of semiflexible polymers, the results will also be highly relevant in engineering applications. For example, the study of chain dynamics includes calculating the stress of a polymer under various steady flow conditions and the stress relaxation for a deformed chain. These results will enable us to predict the constitutive behavior of polymer melts and solutions in steady flows as well as their viscoelastic properties. Likewise, one of the problems to be addressed in this research, namely the banding instability in sheared multi-chain liquid crystals, has important consequences in the processing of these materials such as in fiber drawing and injection molding.%%%This grant supports theoretical research on the statistical mechanics of polymers. The use of flexible chain models for polymers, e.g., the freely-jointed chain model, the bead-string or its continuous version of the gaussian model, have contributed considerably to our current understanding of the dynamic and thermodynamic properties of polymers. Many polymer systems, especially biopolymers such as DNA and actin filaments, and main-chain liquid-crystalline polymers, require that the stiffness of the polymer chain be taken into account explicitly. A number of fundamental issues will be addressed in the static and dynamic properties of semiflexible polymers. While the main focus of this work is understanding of the fundamental physics of semiflexible polymers, the results will also be highly relevant in engineering applications. For example, the study of chain dynamics includes calculating the stress of a polymer under various steady flow conditions and the stress relaxation for a deformed chain. These results will enable us to predict the constitutive behavior of polymer melts and solutions in steady flows as well as their viscoelastic properties. Likewise, one of the problems to be addressed in this research, namely the banding instability in sheared multi-chain liquid crystals, has important consequences in the processing of these materials such as in fiber drawing and injection molding.***

9970589wangthis Grant支持有关聚合物统计力学的理论研究。 将柔性链模型用于聚合物，例如，自由关联的链模型，珠子串或其连续的高斯模型版本，为我们当前对聚合物的动态和热力学特性的理解做出了巨大贡献。 许多聚合物系统，尤其是生物聚合物，例如DNA和肌动蛋白丝以及主链液晶聚合物，都要求明确考虑聚合物链的刚度。 半辅助聚合物的静态和动态特性将解决许多基本问题。 其中包括：（1）了解半插针聚合物的单链动力学； （2）理解列在列前场中半串联链的构象和动力学，重点是多发发夹； （3）理解列非半循环聚合物溶液中的相行为，波动和不稳定性。 尽管这项工作的主要重点是了解半辅助聚合物的基本物理学，但结果也将在工程应用中高度相关。 例如，链动力学的研究包括计算各种稳定流条件下聚合物的应力，以及变形链的应力松弛。 这些结果将使我们能够预测聚合物融化和溶液在稳定流以及其粘弹性特性中的本构行为。 同样，这项研究中要解决的问题之一，即剪切的多链液晶中的带状不稳定性，在处理这些材料（例如纤维绘制和注射成型）中产生了重要的后果。%%％该赠款支持对聚合物统计机制的理论研究。 将柔性链模型用于聚合物，例如，自由关联的链模型，珠子串或其连续的高斯模型版本，为我们当前对聚合物的动态和热力学特性的理解做出了巨大贡献。 许多聚合物系统，尤其是生物聚合物，例如DNA和肌动蛋白丝以及主链液晶聚合物，都要求明确考虑聚合物链的刚度。 半辅助聚合物的静态和动态特性将解决许多基本问题。 尽管这项工作的主要重点是了解半辅助聚合物的基本物理学，但结果也将在工程应用中高度相关。 例如，链动力学的研究包括计算各种稳定流条件下聚合物的应力，以及变形链的应力松弛。 这些结果将使我们能够预测聚合物融化和溶液在稳定流以及其粘弹性特性中的本构行为。 同样，这项研究中要解决的问题之一，即剪切的多链液晶中的带子不稳定性，在处理这些材料（例如纤维绘制和注射成型中）时产生了重要的后果。*** ***