RUI: Collapse and folding of a polymer chain: Effects of crowding and confinement

非技术总结这个奖项是根据本科生研究所(RUI)的一项研究提案颁发的，旨在支持计算和理论研究以及教育，以研究长链状分子和聚合物在响应环境变化(如温度和压力变化)时大小和形状的变化。PI将使用先进的计算机模拟技术和模型来促进对这一重要问题的理解。生物细胞中聚合物的大小和形状的改变通常是维持生命在生物分子水平上发挥功能所必需的。对这一过程的更好理解有助于制定智能材料的设计原则，这种设计原则可以根据环境的变化以可逆的方式改变其性能。智能材料有许多应用，包括执行器、传感器和广泛的医疗设备。这项研究计划旨在通过与希拉姆学院的物理课程相衔接，允许学生最大限度地参与其中。核心课程中教授的计算和模拟方法在课堂学习和这项研究计划之间建立了直接联系，并为学生提供了为这项工作做出有意义贡献所需的工具。参与这项研究的本科生将从学习最先进的计算机模拟技术中受益，并将有机会在科学会议上发表演讲。许多在希拉姆与PI一起工作的学生已经或将继续深造物理、材料科学、工程学或医学。PI旨在继续为学生提供成功的教育经验，并帮助招收更多未被充分代表的学生进入科学领域。技术总结这个奖项是根据本科生研究所(RUI)的一项研究提案颁发的，旨在支持计算和理论研究和教育，解决单个聚合物分子的构象相变问题，以响应环境变量的变化，如温度、压力或溶液pH。这一主题具有广泛的重要性，因为含有聚合物的材料的整体性质和生物聚合物以及许多基于聚合物的“智能”材料的功能都与单个聚合物分子的基本微观构象直接相关。许多智能或生物活性材料利用绑在表面的聚合物链，而生物聚合物通常在非常拥挤的大分子环境中工作。在这种几何约束的环境中，聚合物可以表现出不同的行为，本研究的重点是聚合物约束的基本物理，以及在材料设计中的具体应用。这项研究继续并扩展了PI最近在溶剂对聚合物构象的影响和孤立均聚物链的相变方面的重要贡献。本项目的研究目标是：(I)阐明局部环境对单个聚合物链构象相变的影响，例如，与基于聚合物的环境响应型智能材料的设计和功能相关；(Ii)研究单个聚合物的相变，特别是聚合物全折叠或全无折叠，它可以在拥挤或几何受限的环境中提供智能材料应用中的开关；以及(Iii)发展严格的分析工具，如配分函数零点和自由能景观，以研究聚合物体系的相变和相变路径。这项工作将利用PI最近开发的溶剂化势法来降低聚合物-溶剂系统建模的计算复杂性，以及允许直接计算经典多体系统的态密度的先进模拟技术。后一种方法提供了完整的热力学信息，并可用于执行后续的多正则模拟以确定结构信息。这项研究有助于通过发展严格的溶剂化势、态密度模拟方法和新的分析技术来理解单大分子的行为。这将有助于开发基于聚合物的功能材料和仿生材料的合理设计原则。这项研究计划旨在通过与希拉姆学院的物理课程相衔接，允许本科生最大限度地参与其中。在核心物理课程中教授的计算和模拟方法在课堂学习和这项研究计划之间建立了直接联系，并为学生提供了为这项工作做出有意义贡献所需的工具。参与这项研究的本科生将从学习最先进的计算机模拟技术中受益，并将有机会在科学会议上发表演讲。许多在希拉姆与PI一起工作的学生已经或将继续深造物理、材料科学、工程学或医学。国际学生联合会的目标是继续为学生提供成功的教育经验，并帮助招收更多代表不足的学生进入科学界。

NONTECHNICAL SUMMARYThis award made on a Research at an Undergraduate Institute (RUI)proposal supports computational and theoretical research and education to study transformations in the size and shape assumed by long chain-like molecules, polymers, as they respond to changes in their environment, such as changes in temperature and pressure. The PI will use advanced computer simulation techniques and models to advance understanding of this important problem. Changes in the size and shape of the polymers in biological cells are often necessary to carry out functions at the biomolecular level to sustain life. A better understanding of this process contributes to developing design principles for smart materials that change their properties in response to changes in their environment in a way that is reversible. Smart materials have many applications, including actuators, sensors, and a wide range of medical devices.This research program has been designed to allow for maximum student participation by dovetailing into the physics curriculum at Hiram College. Computation and simulation methods taught in the core courses establish a direct link between classroom learning and this research program and provide students with the tools needed to make meaningful contributions to this work. The undergraduate students who participate in this research will benefit by learning state of the art computer simulation techniques and will have opportunities to present at scientific meetings. Many students who have worked with the PI at Hiram, have, or will be, pursuing advanced study in physics, materials science, engineering, or medicine. The PI aims to continue to provide successful educational experiences for students, and to help recruit more under-represented students into the sciences.TECHNICAL SUMMARYThis award made on an Research at an Undergraduate Institution (RUI) proposal supports computational and theoretical research and education that addresses conformational phase transitions of single polymer molecules in response to variations in environmental variables such as temperature, pressure, or solution pH. This topic is of broad importance since both the bulk properties of polymer containing materials and the functionality of biopolymers and many polymer-based "smart" materials are directly linked to the underlying microscopic conformation of individual polymer molecules. Many smart or biologically active materials utilize polymer chains tethered to surfaces while biopolymers typically operate in very crowded macromolecular environments. In this geometrically constrained environment polymers can behave differently and a focus of this research is on the basic physics of polymer confinement with specific applications to materials design. This research continues and extends recent work by the PI with significant contributions from undergraduate collaborators in the areas of solvent effects on polymer conformation and phase transitions of isolated homopolymer chains.The research objectives of this project are to: (i) elucidate the effects of local environment on the conformational phase transitions of a single polymer chain as relevant, for example, to the design and function of polymer-based environmentally responsive smart materials; (ii) study single-polymer phase transitions, in particular, polymer all-or-none "folding", which can provide an on/off switch in smart materials applications, in crowded or geometrically confined environments; and (iii) develop rigorous analysis tools such as partition function zeros and free energy landscapes to study phase transitions and transition pathways in polymer systems. This work will make use of both a solvation potential approach, recently developed by the PI to reduce computational complexity in modeling polymer-solvent systems, and advanced simulation techniques that allow for direct computation of the density of states of classical many-body systems. The latter methods provide complete thermodynamic information and can be used to carry out subsequent multi-canonical simulations to determine structural information. This research contributes to the understanding of single-macromolecule behavior through the development of rigorous solvation potentials, density of states simulation methods, and new analysis techniques. It will contribute to efforts to develop rational design principles for functional polymer-based and biomimetic materials. This research program has been designed to allow for maximum undergraduate student participation by dovetailing into the physics curriculum at Hiram College. Computation and simulation methods taught in the core physics courses establish a direct link between classroom learning and this research program, and provide students with the tools needed to make meaningful contributions to this work. The undergraduate students who participate in this research will benefit by learning state of the art computer simulation techniques and will have opportunities to present at scientific meetings. Many students who have worked with the PI at Hiram, have, or will be, pursuing advanced study in physics, materials science, engineering, or medicine. The PI aims to continue to provide successful educational experiences for students, and to help recruit more under-represented students into the sciences.