Alkylated sulfonated poly(arylene sulfone)s for proton exchange membranes

The attachment of flexible spacers into aromatic polymers is a molecular design approach that is used for improving processability of aromatic polymers. The concept is attractive because it enables not only the creation of aromatic polymers with improved processability but it is also possible to control phase morphology by simply introducing pendant side chains. Here we report new bisphenol A derivatives bearing alkyl chains of different lengths obtained by an addition reaction can readily make novel poly(arylene sulfone)s with aromatic dihalides and aromatic dioles. They were observed using two-dimension diffusion-ordered spectroscopy nuclear magnetic resonance (2D DOSY NMR) spectra. Attaching flexible alkyl groups into sulfonated poly(arylene sulfone)s allows for increased control of glass transition temperatures, Tg, of sulfonated poly(arylene sulfone)s. The alkylated sulfonated poly(arylene sulfone)s had flexibility, increased surface contact angle, improved methanol permeability, and high ion conductivity compared to the neat polymer. Due to the creation of aromatic polymers with improved processability by simply introducing pedant side chains, this novel alkylation method is expected to be applicable to other arylene based proton conductive polymers.