The synthesis and characterizations of original fluorinated copolymers bearing phosphonic acid side functions for novel membranes potentially involved in fuel cell applications are presented. These copolymers were obtained by chemical modifications of various poly(CTFE-alt-IEVE) and poly[(CTFE-alt-IEVE)-co-(CTFE-EVE)] terpolymers (where CTFE, IEVE, and EVE stand for chlorotrifluoroethylene, 2-iodoethyl vinyl ether, and ethyl vinyl ether) via the Arbuzov reaction. Then, the hydrolysis of the phosphonate moieties into phosphonic acid groups was carried out quantitatively in mild conditions, in the presence of bromotrimethylsilane. The ionic exchange capacities (IECs) determined by potentiometric titration were ranging from 2.9 to 6.8 mequiv/g. The thermal and electrochemical properties of the resulting membranes (processed by casting) were investigated. Whatever the phosphonic acid content, the main degradation started from 250°C, showing a high thermo-oxidative stability of these copolymers. At 25°C and 100% relative humidity (RH), the level of conductivity was found in the range 0.02-20 mS/cm and highly dependent on the IEC. Finally, moderate to good conductivity values (about 0.25 mS/cm) at higher temperature (120°C) and lower RH (25%) were observed, which demonstrated a limited dependence toward both temperature and RH.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.