Fabrication and characterization of interpenetrating network hydrogels based on sequential amine-anhydride reaction and photopolymerization in water

Herein, interpenetrating network (IPN) hydrogels were successfully prepared for the first time through integrating two cross-linking reactions in water in one pot, including amine-anhydride reaction and subsequent photopolymerization. First, the polymer containing anhydride groups was prepared via free radical copolymerization of maleic anhydride and acrylamide. Second, the as-prepared polymer was dissolved in water with polyacrylamine hydrochloride, N -isopropylacrylamide, polyethylene glycol dimethacrylate, 2-acrylamido-2-methylpropanesulfonic acid, and photoinitiator to obtain a homogeneous transparent solution. Third, the mixed solution was put in water bath of 50°C for 1 h to obtain the first network via the amine-anhydride click reaction. Afterward, the second network was formed by photopolymerization. Finally, the swelling and drug release behavior of the hydrogels were studied with isoniazid as a model drug. The results show the IPN hydrogel possesses pH and temperature sensitivity and their controlled-release behavior can be tuned via adjusting pH and temperature. In view of the advantages of amine-anhydride reaction and photopolymerization, the strategy described here is of significance for the preparation of IPN hydrogel.