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.***

9970589王本基金用于聚合物统计力学的理论研究。聚合物柔性链模型的使用，例如，自由连接链模型，串珠链或其连续版本的高斯模型，极大地促进了我们目前对聚合物的动力学和热力学性质的理解。许多聚合物体系，特别是生物聚合物，如DNA和肌动蛋白丝，以及主链液晶聚合物，要求明确考虑聚合物链的刚度。一些基本问题将解决在静态和动态性质的半柔性聚合物。这些包括：(1)了解半柔性聚合物的单链动力学；(2)了解向列场中半柔性链的构象和动力学，重点关注多个发夹；(3)了解向列型半柔性聚合物溶液中的相行为、波动和不稳定性。虽然这项工作的主要重点是了解半柔性聚合物的基本物理性质，但其结果也将与工程应用高度相关。例如，链动力学的研究包括计算聚合物在各种稳定流动条件下的应力和变形链的应力松弛。这些结果将使我们能够预测聚合物熔体和溶液在稳定流动中的本构行为以及它们的粘弹性。同样，本研究要解决的问题之一，即剪切多链液晶中的带状不稳定性，对这些材料的加工，如纤维拉伸和注射成型具有重要影响。这笔经费用于支持聚合物统计力学的理论研究。聚合物柔性链模型的使用，例如，自由连接链模型，串珠链或其连续版本的高斯模型，极大地促进了我们目前对聚合物的动力学和热力学性质的理解。许多聚合物体系，特别是生物聚合物，如DNA和肌动蛋白丝，以及主链液晶聚合物，要求明确考虑聚合物链的刚度。一些基本问题将解决在静态和动态性质的半柔性聚合物。虽然这项工作的主要重点是了解半柔性聚合物的基本物理性质，但其结果也将与工程应用高度相关。例如，链动力学的研究包括计算聚合物在各种稳定流动条件下的应力和变形链的应力松弛。这些结果将使我们能够预测聚合物熔体和溶液在稳定流动中的本构行为以及它们的粘弹性。同样，本研究要解决的问题之一，即剪切多链液晶中的带不稳定性，对这些材料的加工，如纤维拉伸和注射成型具有重要影响。***