Interpenetrating polymer network hydrogels based on poly(ethylene glycol) macromer and chitosan

Interpenetrating polymer network (IPN) hydrogels were prepared by UV irradiation of solutions in mild aqueous acid media of poly(ethylene glycol) macromer (PEGM) with chitosan in the presence of glutaraldehyde as a crosslinking agent. Hydrogels obtained were characterized by using FT-IR, FT-Raman, wide angle X-ray diffractometry (WAXD), differential scanning calorimetry (DSC) and dielectric analysis (DEA). Equilibrium water content (EWC) of these hydrogels was in the range of 74¯97%. Photocrosslinked PEGM segments within the IPNs had considerably reduced crystallinities compared to PEGM itself. All the IPNs revealed two glass transition temperatures (Tg), indicating the presence of phase separation in the IPNs. In addition, Tg values of PEGM segments were reduced with decreasing crosslinking degree. The tensile strength and elongation at break of IPNs hydrogels in the swollen state ranged from 0.06 to 0.18 MPa and 18¯48%, respectively.