Swelling Behaviors of Polyaniline-Poly(Acrylic Acid) Hydrogels

Using poly(acrylic acid) (PAA) aqueous solution, NaOH aqueous solution, aniline(An) and ammonium persulfate(APS), PAn-PAA hydrogels with a semi-interpenetrating structure connected by physical interlocks, chemical ion bonds and hydrogen bonds were prepared. The swelling properties of the hydrogels in solutions of different pH values (adjusted by adding NaOH or HCl) were studied. All the hydrogels prepared have similar swelling curves (the curves of equilibrium swelling ratio vs. pH value) and reach their maximum swelling at pH of 810. The maximum swelling ratio of the hydrogels is dependent on composition, including molecular weight of PAA, polymer content of the hydrogel, and molar ratios of AA to An, APS to An, and NaOH to AA. And the compositional dependence of the swelling capacity of PAn-PAA hydrogels was also studied.