Phosphonation of polysulfones via lithiation and reaction with chlorophosphonic acid esters

A noncatalytic route for the phosphonation of polysulfones was established in which lithiated sites on polysulfones were reacted with an excess of chlorophosphonic acid esters through an SNP(V) mechanism. Both the bisphenol A and biphenyl sulfone segments of the polysulfone main chain were modified according to whether brominated polysulfone or pristine polysulfone was used. Up to 50% of the repeating units of the polysulfones were modified by a careful selection of reaction parameters to avoid crosslinking. The phosphonated polysulfones in their acid form showed high thermal stability with decomposition temperatures of approximately 350 C under nitrogen. Polysulfones with phosphonated bisphenol A segments showed good membrane-forming properties and are candidates for components in ionomer composite membranes for fuel cells. (C) 2004 Wiley Periodicals, Inc.