Synthesis of the Diazonium Zwitterionic Polymer/Monomer for Use as the Electrolyte in Polymer Electrolyte Membrane (PEM) Fuel Cells

• Main Author: Marshall, Josiah
• Format: Others
• Language: English
• Published: Digital Commons @ East Tennessee State University 2021
• Subjects: Proton exchange membrane; diazonium; perfluoroalkylsulfonylimide polymers; Materials Chemistry; Organic Chemistry; Polymer Chemistry
• Online Access: https://dc.etsu.edu/etd/3968; https://dc.etsu.edu/cgi/viewcontent.cgi?article=5453&context=etd

My research goals are to synthesize new zwitterionic perfluorosulfonimide (PFSI) monomer/polymers. They are expected to replace traditionally used perfluorosulfonic acid (PFSA) polymers as the electrolyte in PEM fuel cells. For the PFSI monomer preparation, we designed a nine-step synthesis route. Thus far, I have successfully completed the synthesis of 4- (2-bromotetrafluoroethoxy)-benzenesulfonyl amide, 4-acetoxybenzenesulfonic acid sodium salt, and 4-chlorosulfonyl phenyl acetate. The coupling reaction of 4-(2-bromotetrafluoroethoxy)- benzenesulfonyl amide with 4-chlorosulfonyl phenyl acetate, was troublesome due to slow reaction kinetics and byproducts. Additionally, I did a methodology study for the homopolymerziation of the perfluoro 3(oxapent-4-ene) sulfonyl fluoride monomer. We compared the weight average molecular weight (Mw) of different reaction conditions. The best Mw was achieved when the polymerization was carried out for five days at 100 °C and150 psi with 2 wt % initiator and 5 g of monomer. All the compounds were characterized by melting point, GC-MS, GPC, FT-IR, and 13C/1H/19F NMR.