The effect of oxidation of copoly (L-alanine, L-methionine) membranes on oxygen permeability and tensile properties.

This study pertains to the development of poly (alpha-amino acid) membranes which have potential as biomaterials. Copoly (L-alanine, L-methionine) membranes have been subjected to oxidation which produced a hydrophilic structure allowing the improvement of oxygen permeability. L-Methionine residues in the copolymers were converted to methionine sulfoxide and/or sulfone groups by action of hydrogen peroxide in various reaction compositions. Water absorption, permeability to oxygen dissolved in water, and tensile strength of the modified membranes were changed with the extent of oxidation. The water absorption was found to increase with oxidation time from 10 to 300%. The oxidation time dependency on the oxygen permeability coincided with the increase in the water absorption. The permeability coefficients of oxidized membranes were of the order of 10(-9) cm3 (STP) cm/cm2 s cm Hg, while those of unoxidized membranes were approximately 10(-11). As expected, the tensile strengths of oxidized membranes were smaller than those of unoxidized ones. In addition, the effect of L-alanine and L-methionine residue composition on the membrane properties is discussed.