PH‐induced reversible permeability control of the 4‐carboxy acrylanilide‐methyl methacrylate copolymer membrane

Abstract

AbstractTo develop a polymer membrane whose permeability of water‐soluble compounds could be controlled in response to a pH change of the medium, a polyelectrolyte membrane containing an aromatic carboxyl group, i.e., 4‐carboxyacrylanilide (CAAn)‐methyl methacrylate(MMA) copolymer membrane, was prepared. The water content of the CAAn‐MMA copolymer membrane increased with increasing pH owing to ionization change in the CAAn moiety. This increase was particularly remarkable in the pH range from 5 to 7. The change in water content was reversible and could be controlled by the CAAn composition in the copolymer. Permeation of 1,4‐bis(2‐hydroxyethoxy)benzene(DHEB) through the CAAn‐MMA copolymer membrane was investigated in solutions of various pH. Change in the permeability of DHEB in function of the pH was similar to the change in membrane water content. This was explained by an increase in the permeation pathway of DHEB in the membrane, in proportion to that in the water content. Moreover, when a pH‐sensitive membrane was placed in a solution in which an enzymatic reaction occurred, substrate‐induced permeation control of DHEB through the CAAn‐MMA copolymer membrane was possible.