A technique has been developed to prepare crosslinked, porous membrane from a chemical modification of polystyrene. Polystyrene was chemically modified by crosslinking with pyromellitic dianhydride in nitrobenzene using a Friedel-Crafts acylation reaction in the presence of AlCl3 at 100 degrees C. Solid-state cross polarization/magic angle spinning NMR of powdered membrane was reported. TGA of the membrane was verified in air and in nitrogen. The morphologies of the membranes were analyzed.