| Development of novel perfluoropolymers containing carbon acid function for use as a solid polymer electrolyte (SPE) in polymer electrolyte membrane fuel cells (PEMFC's) and other electrochemical applications was the focus of this work. These copolymers were synthesized from comonomers TFE and the corresponding carbon acid monomers CF2=CFOCF2CF 2SO2CH2SO2CF3 (A), CF2=CFO-CF2CF(CF3)OCF2CF 2SO2CH2SO2CF3 (B), or CF2=CFOCF2CF(CF3)OCF2CF 2-SO2CH(SO2CF3)2 ( D). A, B, and D comonomers were synthesized from somewhat novel and inexpensive routes in moderate to high yields. The development of these monomers was accomplished through a variety of synthetic methodologies. Along with the, development of these monomers, intermediate products produced were reacted with a variety of compounds to introduce the CF3SO- or CF3SO2CH2- group.; Current monomer synthesis of A and B are carried out after isolation of trifluoro(methylsulfonyl)methane, CF3SO 2CH3, which was prepared from S-alkylation of CF3SO 2Na with CH3I in tetramethylene sulfone, in yields up to 92%. The CF3SO2Na, sodium trifluoromethyl sulfinate, is synthesized using trifluorobromomethane, CF3Br, and dithionate with buffer in N,N-Dimethylformamide (DMF) and water in yields up to 85–92% based on consumed CF3Br. CF3SO2CH3 was then reacted with methlymagnesium bromide affording a transmetallated species, CF3SO2CH2MgBr. Reactions of CF 3SO2CH2MgBr with CF2=CFOCF2CF 2SO2F or CF2=C(F)OCF2CF(CF3)OCF 2CF2SO2F in diethyl ether, followed by acidification, gives the corresponding carbon acid monomer CF2=CFOCF2CF 2SO2CH2SO2CF3 (A) or CF2=CFOCF2CF(CF3)OCF2CF 2-SO2CH2SO2CF3 (B ). CF2=CFOCF2CF(CF3)OCF2CF 2SO2CH(SO2CF3)2 (D) was synthesized using (CF3SO2) 2CKMgBr dianion with the CF2=CFOCF2CF(CF 3)OCF2CF2SO2F.; Aqueous emulsion polymerization routes have been utilized to produce copolymers A1, B2, and D3, in various ion exchange capacities (IEC) and equivalent weights (EW) in order to produce polymers with good potential for fuel cell applications. The current process is a continuous, redox initiated, free radical aqueous emulsion polymerization carried out at lower temperature and is the process of choice. It is believed that this process provides more random co-polymer with high molecular weight, good mechanical properties, and thermal stability. Although the morphology of the sulfone carbon acid polymers A1, B2 and D3 are uncertain, properties of these materials and their viability for use in PEM fuel cells will be discussed.; These materials may provide more efficient oxygen reduction at the cathode increasing the performance of a PEM fuel cell, but they have not yet been evaluated as PEM's in fuel cells or in electrode inks in MEA's.*; *Please refer to dissertation for diagram. |
