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.***

9970589Wang该资助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、珠串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动态和热力学性质的理解。 许多聚合物系统，特别是DNA和肌动蛋白丝等生物聚合物以及主链液晶聚合物，需要明确考虑聚合物链的刚度。 半柔性聚合物的静态和动态特性中的许多基本问题将得到解决。 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，重点关注多个发夹结构； (3) 了解向列型半柔性聚合物溶液的相行为、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础物理，但其结果也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态流动条件下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熔体和溶液在稳定流动中的本构行为及其粘弹性能。 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（例如纤维拉丝和注塑成型）具有重要影响。%%%这项资助支持理论聚合物统计力学研究。 聚合物柔性链模型的使用，例如自由连接链模型、珠串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动态和热力学性质的理解。 许多聚合物系统，特别是DNA和肌动蛋白丝等生物聚合物以及主链液晶聚合物，需要明确考虑聚合物链的刚度。 半柔性聚合物的静态和动态特性中的许多基本问题将得到解决。 虽然这项工作的主要重点是了解半柔性聚合物的基础物理，但其结果也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态流动条件下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熔体和溶液在稳定流动中的本构行为及其粘弹性能。 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（例如纤维拉丝和注塑成型）具有重要影响。***