Sulfonated poly(aryl ether ketone)s

Several kinds of commercially available polymers of the type poly(oxy-1,4-p henylenecarbonyl-1,4-phenylene) were sulfonated by reaction with mixtures o f sulfuric acid and oleum. The ether/carbonyl group ratio of the polymer ch ain varied from 0.67 to 2.0. With decreasing amounts of ether links in the polymer backbone the sulfonation is hindered and the reaction conditions ha ve to be stronger. To yield the same degree of sulfonation, the sulfuric tr ioxide concentration of the reaction mixture has to be increased. The achie vable degree of substitution is limited, in general, to one sulfonate group per substitutable unit (oxyphenylene-oxy- or oxy-phenylene-carbonyl unit). In dependence on the polymer structure, polymers with contents of sulfonate groups between 1.2 and 2.0 meq.g(-1) polymer are well soluble in dimethylf ormamide or N-methylpyrrolidone and it is possible to produce membranes wit h permselectivities >96% and electrical resistances <2 Omega cm(-2) . The sulfonated polymers were characterized by viscosimetry, sedimentation a nalysis and C-13 NMR spectroscopy.