Statistical Mechanics of Semiflexible Polymers

9970589 Wang该基金支持聚合物统计力学的理论研究。 聚合物的柔性链模型的使用，例如，自由连接的链模型、珠串或其高斯模型的连续形式对我们目前对聚合物的动力学和热力学性质的理解做出了相当大的贡献。 许多聚合物系统，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，需要明确考虑聚合物链的刚度。 在半柔性聚合物的静态和动态性质中，将讨论一些基本问题。 其中包括：（1）了解半柔性聚合物的单链动力学;（2）了解半柔性链在电场中的构象和动力学，重点是多个发夹;（3）了解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础物理，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态流动中的本构行为以及它们的粘弹性。 同样，本研究中要解决的问题之一，即剪切多链液晶中的条带不稳定性，在这些材料的加工中，如纤维拉伸和注塑成型中具有重要的后果。该基金支持聚合物统计力学的理论研究。 聚合物的柔性链模型的使用，例如，自由连接的链模型、珠串或其高斯模型的连续形式对我们目前对聚合物的动力学和热力学性质的理解做出了相当大的贡献。 许多聚合物系统，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，需要明确考虑聚合物链的刚度。 在半柔性聚合物的静态和动态性质中，将讨论一些基本问题。 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态流动中的本构行为以及它们的粘弹性。 同样，本研究中要解决的问题之一，即剪切多链液晶中的条带不稳定性，在这些材料的加工中，如纤维拉伸和注塑成型中具有重要的后果。

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.***