Solution and Interfacial Properties of Catenated Polymers

University Of Akron, Akron OH

Investigators

Abstract

NONTECHNICAL SUMMARY Door 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 SUMMARY This 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.