Abstract: A method for sulfonation of poly(phenylene ether) can comprise: dissolving a poly(phenylene ether) comprising 2,6-dimethyl-1,4-phenylene ether units, 2,3,6-trimethyl-1,4-phenylene ether units, 3,3?,5,5?-tetramethyl-4,4?-dihydroxybiphenyl ether units, or a combination thereof in a mixture of 1,2-dichloroethane and a cosolvent to form a solvent mixture in a mixing vessel, wherein the cosolvent comprises at least one of methyl ethyl ketone, diethyl ether, methyl ethyl sulfone, ethyl acetate, or tetramethylene sulfone; combining a sulfonating agent with the solvent mixture, wherein the sulfonating agent reacts with the poly(phenylene ether) to form sulfonated poly(phenylene ether); precipitating the sulfonated poly(phenylene ether); and filtering the precipitated sulfonated poly(phenylene ether) to form a sulfonated poly(phenylene ether) precipitate and a filtrate; wherein the sulfonated poly(phenylene ether) has a sulfonation level of 20 to 50%.