Characterization of Degraded Hydrogels Based on Poly(vinyl alcohol) Grafted with Poly(lactide-co-glycolide)

Poly(vinyl alcohol) (PVA) grafted with poly(lactide-co-glycolide) and cross-linked as a material of increased hydrophobicity relative to PVA was produced. The properties were examined with respect to the mass loss, water uptake, hydrophilicity, and mechanical characteristics upon hydrolytical degradation. The hydrogels investigated display water uptake increasing with degradation time because of increasing hydrophilicity. The mass loss amounts up to 15% after eight weeks of degradation. The mechanical properties of the hydrogels are within the range of those of natural tissue, the E modulus is 18 MPa, or even 100-200 MPa, depending on the structure of material. The mechanical characteristic and their dependence degradation show the most recognizable correlation with the chemical structure. Studies of the topography of degraded samples (scanning electron microscopy) and IR measurements demonstrate the degradation to occur at slow rate due to the high degree of grafting. The mass loss is rather low and a bulk degradation mechanism takes place. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 1322-1329, 2011