CAS: Electrochemical and Photochemical Methods for Precision Synthesis of Conjugated Polymers

University Of California-San Diego, La Jolla CA

Investigators

Abstract

With the support of the Macromolecular, Supramolecular and Nanochemistry program in the Division of Chemistry, Nathan Romero of the University of California at San Diego is developing electrochemical and photochemical methods for precision synthesis of conjugated polymers. Conjugated polymers carry significant potential for applications as organic electronic materials owing to their lightweight, flexible nature and diverse optoelectronic properties. However, realization of advanced technologies necessitates a degree of structural control beyond current synthetic capabilities. This work addresses this limitation and will seek to achieve length- and sequence-controlled polymerization of conjugated polymers using a combination of electrochemical and photochemical tools to polymerize a broad range of simple arene substrates. The developed methodology will be applied to the synthesis of novel polymers for organic electronics and new methods for additive manufacturing. The synthetic innovations associated with this research have the potential to create advanced organic electronic devices with applications in sustainable energy, healthcare, and communications. Furthermore, the designed photochemical reactivity of monomers may be applicable to the upcycling of conjugated polymers once used rather than discard these as waste. The interdisciplinary nature of this research will provide educational and professional development opportunities for student researchers. The research team will work to increase representation of non-majority scholars through inclusive mentoring, teaching and service. Outreach activities to local communities will focus on educational resources related to electronic waste handling and disposal, sustainable polymer feedstocks and biodegradable plastics. This research will focus on developing the length- and sequence-controlled polymerization of thiophene based monomers using a combination of electrochemical and photochemical tools. The modular platform for precision synthesis of conjugated polymers will utilize electrochemical C-H functionalization to selectively couple an arene and a sulfide to form an arylsulfonium salt, which will also serve as monomer in a novel photo-mediated chain growth polymerization. By performing electrolysis and photolysis simultaneously, the sulfide will essentially act as a catalyst to achieve controlled oxidative polymerization. The developed direct method for the preparation of arylsulfonium salts through C-H functionalization aims to improve upon the atom economy of existing multi-step chemical methods. The photopolymerization studies have the potential to provide fundamental knowledge on the photochemical reactivity of conjugated polymers and introduce conceptually novel mechanisms for controlling molecular weight through wavelength modulation. Strategies that reduce the reliance on transition metals for polymerizing aromatic units are important for improving the sustainability of polymer science and technology. In general terms, this research has the potential to provide a more universal approach to sequence-defined and controlled polymerizations of conjugated polymers. 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.