CAREER: Bridging the Gap Between Bottlebrush and Comb Polymers with Precision Macroinitiators to Generate New Elastomeric Materials

Florida State University, Tallahassee FL

Investigators

Abstract

NON-TECHNICAL SUMMARY In this project the PI and his students will synthesize, characterize, and determine a variety of material properties for a new class of high-performance elastic polymers that may have super-elastic or super-soft properties. Prominent advances in polymer chemistry over the last several decades have ushered in the ability to design a variety of molecular architectures with a high degree of control and functional versatility. The development of new molecular architectures that synergize the features of advanced functionality and enhanced elasticity is the primary objective of this research. The proposed work is hypothesized to produce ultra-flexible materials and super-soft gels that are potentially superior and could have applications as lubricants, articular cartilage (knee or joint) replacements, and protective equipment that reduces force impact. A new class of architectures of polymer molecules having bottlebrush-network shapes will be designed and explored, which is expected to lead to special super-elastic properties. This research will be integrated with broader impacts of education for undergraduates, graduates, and the local community. It will contribute to nurturing the growing research in polymer science at FSU and the nation. A three-point plan focuses on curriculum development, collaborative events, and community outreach directed towards underrepresented groups in polymer science. Education about plastics, their challenges, and their opportunities to solve societal needs for future generations will be undertaken and integrated with the proposed research. TECHNICAL SUMMARY The design of bottlebrush (BB) systems for frontier materials applications places emphasis on the degree of polymerization of the backbone and the side chains in addition to graft density. Although these coarse dials serve as a means to begin understanding of these unique architectures, there are other synthetic components which may present a means potentially to discover new properties. A majority of BB systems are derived from the polymerization of either a vinyl monomer or norbornene to produce a variety of graft chemistries affixed to a highly limited number of backbone options. This work proposes to expand the suite of backbone chemistries possible through the use of precise polypentenamer scaffolds suited to produce BB systems through a "grafting-from" approach. These materials will produce a graft at exactly every fifth carbon (similar to polynorbornenes) but with a flexible rubber-like backbone chemistry between each graft site. It is hypothesized that the reduced Kuhn length associated with this flexible backbone will result in amplified sensitivity as the size of the grafts increase and begin to occupy the pervaded volume around it. Such dynamic behavior will be fully studied through light scattering and viscoelastic measurements as a function of the synthetic design principles that elucidate variances in the aforementioned coarse dials for BB systems. The results will be corroborated with developing theoretical and computational treatments for BB systems. Given the rubber-like backbone, a natural extension for such systems towards superelastic and supersoft networks will be explored to provide potentially transformative materials for use in lubrication and impact dampening. A three-point plan will be implemented to increase the education in polymer science at FSU and the surrounding community through enhanced curriculum, collaborative events, and outreach. Undergraduates will be offered an advanced elective in polymer synthesis. Research focused around polymer science will be highlighted with an FSU annual poster session. Finally, continued efforts to reach out to the surrounding community through a plastics education exhibit will bring to light societal aspects that involve polymer science. 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.