SYNOPSISPermeabilities of cast films of methylmethacrylate-co-methacrylic acid ( MMA-MAA) and its 5% neutralized Na'+, CS'+, Zn2+, Ba2+, and A13+ ionomers for urea, sodium chloride, and creatinine were determined using a double (donor and acceptor) compartment cell. Film permeability was increased as the ionic potential decreased and it was more marked with urea as compared with sodium chloride and creatinine. Tensile properties of the above samples were also tested and variations in Young's Moduli were based on the effect of type of aggregates produced by the cations in the matrix of the copolymer. 0 1993 John Wiley & Sons, Inc.