Physico-chemical characterization of modified poly(vinyl alcohol) based hydrogels

The study reports the preparation and characterization of modified PVA based hydrogels with biomedical applications as carriers for drug delivery systems. PVA modified copolymers were previously synthesized by grafting with L-lactic acid, using manganese acetate as catalyst and different molar ratio of PVA/L(+)-lactic acid (1/1; 1.5/1; 2.2/1). The hydrogels were synthesized using sodium tetraborate (Na2B4O7 center dot 10H(2)O) as crosslinking agent, triethylenetetramine as accelerator, in water system at room temperature. Crosslinking agent concentration varied between 5 and 12 wt. % depending on poly(vinyl alcohol) grafting degree. After crosslinking, the hydrogels were maintained 24 hours at room temperature, then were introduced in the freezer (-22 degrees C) for 6 h and subsequently were dried by lyophilization (-48 degrees C) to constant weight. The swelling properties of the synthesized hydrogels were investigated in phosphate buffer (pH 7.4) at 37 degrees C temperature. The hydrogels were characterized by infrared spectroscopy (IR), thermal analysis (DTG, DSC).