Radiation preparation and characterization of pH-sensitive hydrogel of acrylamide/β-cyclodextrin copolymer

A β-cyclodextrin(β-CD)based monomer(MAH-β-CD)containing vinyl and carboxyl functional groups was synthesized by reaction of β-CD with maleic anhydride(MAH).By copolymerization of the monomer with acrylamide(AAm),a novel hydrogel,poly(AAm-co-MAH-β-CD)with pH and ionic strength sensitivities plus molecular inclusion function,was obtained by irradiating the aqueous solution mixture of AAm and MAH-β-CD with electron beam.The effect of the feed ratio of components and irradiation dose on the swelling and deswelling properties of the hydrogel was systematically studied.Swelling ratio of the hydrogel was tested under different environment of pH and ionic strength.The results indicate that the copolymer hydrogels did not show any noticeable change in swelling at lower pH(pH5).However,they showed an abrupt increase in swelling at pH 5～8 due to the ionization of carboxyl groups.