Upon the characterization of semi-synthetic hydrogels based on poly (NIPAM) inserted onto collagen sponge

The preparation of a semi-synthetic hydrogel based on poly(N-isopropyl acrylamide-co-diethylene glycol diacrylate) inserted onto a collagen porous membrane, it was previous presented. The synthesis of the hydrogels was performed through radical copolymerization of N-isopropyl acrylamide (NIPAM) with diethylene glycol diacrylate (DEGDA) also as crosslinking agent, using ammonium persulfate as initiator and N,N,N′,N′-tetramethylethylene diamine activator, and it was achieved in the presence of the collagen matrix. In this paper the thus prepared hydrogels are characterized by Differential Scanning Calorimetry, Scanning Electron Microscopy and for their swelling capacities. A kinetic model was studied to investigate the swelling mechanism of the semi-interpenetrated polymeric network. The swelling behavior was found dependent on the hydrogel composition and to the external stimuli such as temperature and pH of environment. This manner of acting recommends these materials as smart materials with potential applications in tissue engineering and pharmaceutical field as for example bioproducts carrier matrices.