Research Initiation Award Grant: Synthesize and Characterize of Disulfonated Poly(arylene ether sulfone-tetrachlorocyclotriphosphazene) Hybrid Copolymers

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Fisk University's Research Initiation Award entitled - Synthesize and Characterize of Disulfonated Poly(arylene ether sulfone-tetrachlorocyclotriphosphazene) Hybrid Copolymers - has the goal to synthesize disulfonated poly(arylene ether sulfone tetrachlorocyclotriphosphazene) (PAES-TCCP) hybrid copolymers as proton exchange membranes (PEM) for fuel cells. Polymer membranes created to date are insufficiently proton conductive to be useful for fuel cells. The project will combine the unique properties of hexachlorocyclotriphosphazene (HCCP) monomer with disulfonated poly(arylene ether sulfone) (PAES) copolymer to prepare novel hybrid polymers with increased hydrophilicity, high proton conductivity, thermal stability, and mechanical properties. However, harsh post sulfonation reactions typically reported to modify HCCP preformed polymers led to both irreproducible and crosslinked products. To overcome these limitations, a two-step method for preparing disulfonated linear PAES-TCCP hybrid copolymers is proposed. In the first step, hybrid monomers based on hexachlorocyclotriphosphazene and biphenols monomers will be prepared; the phenolic endgroups of the bisphenol monomers will serve as the reactive site for polymerization to overcome the steric hindrance associated with the HCCP monomer, thus increasing polymer molecular weight. Secondly, linear PAES-TCCP hybrid copolymers will be synthesized by direct copolymerization of the hybrid monomers with disulfonated 4, 4'-dichlorodiphenylsulfone (SDCDPS) and unsulfonated 4, 4'-dichlorodiphenylsulfone (DCDPS) monomers. Retention of the chlorides on HCCP prior to polymerization will allow post-modifications to be carried out along the polymer backbone, providing further reactive sites to subsequently incorporate various functional groups. The expected products will have improved proton conductivity and controlled cross-linking.This project involves undergraduate students from under-represented backgrounds in state-of-the-art polymer research at Fisk University. Students participate in all major aspects of the research, increasing their interest in polymer chemistry through hands-on experiences. Undergraduate research by Fisk students further prepares them to obtain M.S. or PhD degrees for careers in the polymer-related fields.