Poly(styrenesulfonic acid) ion‐exchange membranes having various degrees of porosity and flexibility have been prepared by using aliphatic and aromatic esters of p‐styrenesulfonic acid. The membranes formed from the aliphatic ester monomers were found to exhibit an increase in water uptake, permeability, and flexibility with increase in the size of the alcohol group of the ester monomer. With membranes formed from the phenyl and β‐naphthyl ester monomers the reverse trend was indicated. The flexibility of the membranes formed from the aromatic ester monomers was much greater than that obtained with the aliphatic esters.

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