Solution and Interfacial Properties of Catenated Polymers

门链、雪链、锚索、珠宝项链和锁子甲都由相互连接的金属环组成。由于它们的联锁结构，这些材料结合了灵活性和机械强度。由两个或多个相互缠绕的环组成的类似互锁结构也可以通过化学合成在分子水平上产生，其中每个环仅由一个单一分子组成，称为聚合物或大环。在过去，这些所谓的连环烷和聚连环烷的合成一直局限于短链和低收率。然而，合成方面的最新进展正在推动聚连环烷合成的极限达到新的复杂性和可重复性水平，为在分子马达、可编程电子开关和执行器等纳米级应用中使用聚连环烷打开了一扇门。由于聚连环烷代表了一种新型的基于聚合物的结构，对其材料性质的基本了解仍然有限。该奖项支持理论和计算研究和教育，旨在促进对链链烷和聚链链烷在溶液和界面中的行为的基本理解。首席研究员正在使用最先进的计算机模拟方法和机器学习技术来设计和优化互锁聚合物结构的模型，并使用它们来阐明聚连环烷在特定应用中的材料特性。本研究扩展了当前中尺度和多尺度建模的前沿，作为一种为纳米尺度分子组装的设计提供信息的方法。该项目招收研究生、通过聚合物科学和聚合物工程学院NSF-REU中心的本科生以及来自俄亥俄州阿克伦地区的高中生。该基金资助的首席研究员和研究生将访问为大量少数民族提供服务的当地学校，并鼓励这群学生参加科学课程并从事STEM职业。技术概述：该NSF奖支持理论和计算研究和教育，旨在推进对聚合物结构的基本理解，即连环烷和聚连环烷。链烷和更复杂的聚链烷代表了通过机械键连接在一起的机械互锁的聚合物结构，而不是通常决定聚合物性质的共价键。PI将采用基于串珠弹簧粗粒度模型的分子模拟技术来研究和合理化溶液和界面中连环烷的材料特性。具体项目针对链链聚合物通过狭窄孔隙的易位，链链聚合物刷中的张力分布，以及机器学习引导的链链化合物中尺度模型的开发。该研究为将链链烷纳入聚合物结构的中尺度和多尺度建模提供了基础，从而扩展了当前模拟复杂超分子组装的前沿。该项目涉及研究生，以及通过聚合物科学和聚合物工程学院NSF-REU中心的本科生，以及来自俄亥俄州阿克伦地区的高中生。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 SUMMARYDoor chains, snow chains, anchor cables, jewelry necklaces, and chain mail all consist of interconnected metal rings. Because of their interlocked structure, these materials combine flexibility with mechanical strength. Similarly interlocked structures, consisting of two or more intertwined rings, can also be produced on a molecular level by chemical synthesis, where each ring consists of only one single molecule, known as polymer or macrocycle. In the past, the synthesis of these so-called catenanes and polycatenanes has been limited to short chains and low yields. Recent advances in synthesis, however, are pushing the limits of polycatenane synthesis to new levels of complexity and reproducibility, opening a door toward using polycatenanes in nano-scale applications such as molecular motors, programmable electronic switches, and actuators. Because polycatenanes represent a new type of polymer-based architecture, basic understanding of their material properties remains limited.This award supports theoretical and computational research and education aimed at advancing the fundamental understanding of how catenanes and polycatenanes behave in solution and at interfaces. The principal investigator is using state-of-the-art computer simulation methods and machine learning techniques to design and optimize models for interlocked polymeric architectures and use them to elucidate the material properties of polycatenanes in specific applications. This research extends the current frontier of mesoscale and multiscale modeling as a method of informing the design of nanoscale molecular assemblies. The project engages graduate students, undergraduate students through the NSF-REU center at the School of Polymer Science and Polymer Engineering, and high school students from the Akron, Ohio area. The principal investigator and the graduate students supported by this grant will visit local schools that are serving large numbers of minorities and will encourage this group of students to take science courses and pursue careers in STEM.TECHNICAL SUMMARYThis NSF award supports theoretical and computational research and education aimed at advancing the fundamental understanding of polymer architectures known as catenanes and polycatenanes. Catenanes, together with the more complex polycatenanes, represent mechanically interlocked polymeric structures that are held together by mechanical bonds, not by covalent bonds that usually determine the properties of polymers. The PI will employ molecular simulation techniques based on a bead-spring coarse-grained model to investigate and rationalize the material properties of catenanes in solution and at interfaces. Specific projects target the translocation of catenated polymers through narrow pores, the tension distribution in catenated polymer brushes, and the development of machine learning-guided mesoscale models for catenanes. This research provides groundwork for including catenanes into the mesoscale and multiscale modeling of polymeric architectures and thus extends the current frontier of simulating complex supramolecular assemblies. The project involves graduate students as well as undergraduate students through the NSF-REU center at the School of Polymer Science and Polymer Engineering, and high school students from the Akron, Ohio area.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.