Abstract
In order to obtain the polypeptide membrane having high permeability ratio of oxygen to carbon dioxide gas, the effect of chemical structure of the side chain on permeation and sorption behaviors was studied. Poly (L-methione) (PLM) was selected as the reference material, and its oxidation by hydrogen peroxide aqueous solution was made. The oxidized membranes obtained under severe oxidation condition and under rather mild condition are named as PLMO-I and PLMO-II, respectively. Each membrane has -SO- group in the side chain. Though the PLM and PLMO-II membranes have α-helical structure throughout the membrane, PLMO-I in the surface layer of the membrane may have somewhat disordered helical structure. The ratios of the permeability of oxygen to that of carbon dioxide gas are 0.37 for PLM, 0.53 for PLMO-II and 1.7 for PLMO-I. All of these values are higher than those, 0.1_??_0.2, of usual polymers. The high ratio for PLMO-I is due to the high affinity of oxygen for polymer and low diffusibility of carbon dioxide gas in the partially random coiled structure of the membrane surface layer.
