CAREER: Molecular Modeling of Ring Polymer Mechanics - Expanding Applicability of Ring Polymer

该职业奖支持环形聚合物力学的综合研究、教育和推广项目。常见的聚合材料包括塑料和弹性体，分别用于汽车保险杠和轮胎。力学性能，如拉伸性、柔软性和断裂韧性，是高分子材料正常功能的重要基础。高分子力学的设计始于高分子分子的合成。传统的聚合物是通过将单体连接到具有开放末端的长线性链上制成的，而最近聚合物化学的重大进展使环状聚合物的合成成为可能。环形聚合物为改变聚合物力学提供了前所未有的基石，因为通过环形聚合物独特的环形构象可以引入各种拓扑结构。在这个项目中，PI将结合分子模拟和理论来确定基于转变环拓扑的途径，以定制聚合物力学。PI团队将解决需要解决的基本问题，以利用控制环形聚合物拓扑的合成能力来设计具有定制拓扑结构和机械性能的新型聚合物材料。分子模拟与理论相结合将阐明环形聚合物拓扑结构对实验可控参数的依赖关系，以及环形聚合物在整体、聚合物界面和纳米颗粒聚合物复合材料中的拓扑结构与力学性能之间的关系。这些工作将与实验联系起来，这些实验将指导系统参数的选择，并测试将要进行的计算和理论研究的预测能力。PI的教学和科学推广将利用环聚合物力学的丰富和新颖的研究组合，特别是分子模拟。从PI的研究中得出的模拟将作为高中学生现场研讨会、暑期学生研究项目和分子模拟学习者教程的主要组成部分。通过对微观世界的生动描绘，分子模拟可以很好地向公众传播分子科学。PI的团队将为当地博物馆的游客以及在线媒体的观众设计基于模拟的演示。这些活动将使不同的参与者受益，包括经济困难家庭的成员和在科学、技术、工程和数学（STEM）领域未被充分代表的少数群体。该职业奖支持一项综合研究、教育和推广项目，重点关注环形聚合物在改变聚合物力学中的作用，这些聚合物是多功能聚合物材料正常功能的基础。新型环状聚合物的拓扑结构包括环的非串联，由线性聚合物链穿环，以及串联的“奥林匹克”环。这些拓扑结构与传统线性聚合物及其衍生物的缠结在性质上有所不同，有望丰富基于拓扑的途径，以定制聚合物的机械性能，如拉伸性、柔软性和断裂韧性，用于定制应用。在这个项目中，通过结合分子模拟和理论，PI的团队将描绘环状聚合物在拓扑结构形成中的微观图像，以及在整体、聚合物界面和纳米颗粒聚合物复合材料中各种系统的机械响应。将环高分子化学和物理整合到高分子力学的分子工程中所必需的定量关系将被确定。PI团队将与合成环状聚合物体系的实验学家密切合作，并对其机械性能进行表征，以测试计算和理论工作的结果。提出的研究将验证革命性的想法，扩大环形聚合物在聚合物力学中的能力，并推进环形聚合物知识的前沿。分子模拟可以精确控制聚合物的拓扑结构并直接获取微观信息。再加上拓扑分析，模拟将为循环拓扑在机械变形和断裂中的作用提供无与伦比的见解。传统的聚合物弹性、塑性和断裂力学理论将通过结合最近建立的环状聚合物独特构象和动力学模型而得到扩展。计算和理论的努力将激发化学合成技术的改进，促进环聚合物力学的实验研究，从而建立一个将分子模拟和理论与化学和机械工程相结合的新范式。PI的教学和科学推广将利用环聚合物力学的丰富和新颖的研究组合，特别是分子模拟。从PI的研究中得出的模拟将作为高中学生现场研讨会、暑期学生研究项目和分子模拟学习者教程的主要组成部分。通过对微观世界的生动描绘，分子模拟可以很好地向公众传播分子科学。PI的团队将为当地博物馆的游客以及在线媒体的观众设计基于模拟的演示。这些活动将使不同的参与者受益，包括经济困难家庭的成员和在科学、技术、工程和数学（STEM）领域未被充分代表的少数群体。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NONTECHNICAL SUMMARYThis CAREER award supports an integrated research, education, and outreach project on the mechanics of ring polymers. Common polymeric materials include plastics and elastomers, as used in car bumpers and tires, respectively. Mechanical properties, such as stretchability, softness, and fracture toughness, serve as one critical foundation for the proper functions of polymeric materials. The design of polymer mechanics starts with the synthesis of polymer molecules. While conventional polymers are made by linking monomers to long linear chains with open ends, recent substantial progress in polymer chemistry has enabled the synthesis of ring polymers as closed loops. Ring polymers offer unprecedented building blocks to transform polymer mechanics because various topological structures can be introduced through the unique loopy conformations of ring polymers. In this project, the PI will combine molecular simulations and theory to identify transformative ring-topology-based pathways to tailor polymer mechanics. The team of the PI will address fundamental questions that need to be answered for harnessing the synthetic capability of controlling ring polymer topology to design novel polymeric materials with tailored topological structures and mechanical properties. The combined molecular simulations and theory will elucidate the dependencies of the ring-polymer-based topological structures on experimentally controllable parameters as well as the relations between the topological structures and mechanical properties of ring polymers in the bulk, at polymer interfaces, and in nanoparticle polymer composites. These efforts will be connected to experiments that will guide the choice of the system parameters and test the predictive capability of the computational and theoretical research to carried out. The PI’s teaching and scientific outreach will leverage the rich and novel research portfolio of ring polymer mechanics, especially molecular simulations. Simulations derived from the PI’s research will act as the major components of on-site workshops for high school students, research projects for summer students, and tutorials for learners of molecular simulations. With the vivid rendering of the microscopic world, molecular simulations are well-positioned to disseminate molecular science to the public. The PI’s team will design simulation-based demonstrations for visitors to local museums as well as viewers of online media. The activities will benefit diverse participants including members of economically disadvantaged families and underrepresented minority groups in science, technology, engineering, and mathematics (STEM). TECHNICAL SUMMARYThis CAREER award supports an integrated research, education, and outreach project focusing on the role of ring polymers in transforming polymer mechanics that serve as the foundation for the proper functions of versatile polymeric materials. Novel ring-polymer-based topological structures include the non-concatenation of rings, the threading of a ring by linear polymer chains, and concatenated “Olympic” rings. These topological structures differ qualitatively from the entanglements in conventional linear polymers and their derivatives and are anticipated to enrich the topology-based pathways to tailor the mechanical properties of polymers, such as stretchability, softness, and fracture toughness, for customized applications. In this project, by combining molecular simulations and theories, the PI’s team will delineate the microscopic picture of ring polymers in the formation of topological structures and the mechanical response of various systems in the bulk, at polymer interfaces, and in nanoparticle polymer composites. The quantitative relations necessary for integrating ring polymer chemistry and physics into the molecular engineering of polymer mechanics will be identified. The team of the PI will work closely with experimentalists who synthesize ring-polymer-based systems and characterize their mechanical properties to test the results of the computational and theoretical work. The proposed research will validate the transformative ideas that expand the capabilities of ring polymers in polymer mechanics and advance the frontier of knowledge about ring polymers. Molecular simulations have precise control of polymer topology and direct access to microscopic information. Coupled with a topological analysis, the simulations will provide unparalleled insights into the role of cyclic topology in mechanical deformation and fracture. Traditional theories for the elastic, plastic, and fracture mechanics of polymers will be extended by incorporating more recently established models for the unique conformations and dynamics of ring polymers. The computational and theoretical efforts will motivate the refinement of chemical synthesis techniques, spur experimental studies of ring polymer mechanics, and thus set a new paradigm of integrating molecular simulations and theory with chemistry and mechanical engineering. The PI’s teaching and scientific outreach will leverage the rich and novel research portfolio of ring polymer mechanics, especially molecular simulations. Simulations derived from the PI’s research will act as the major components of on-site workshops for high school students, research projects for summer students, and tutorials for learners of molecular simulations. With the vivid rendering of the microscopic world, molecular simulations are well-positioned to disseminate molecular science to the public. The PI’s team will design simulation-based demonstrations for visitors to local museums as well as viewers of online media. The activities will benefit diverse participants including members of economically disadvantaged families and underrepresented minority groups in science, technology, engineering, and mathematics (STEM).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.