Ultraviolet-induced cross-linking of a functionalized polyaspartamide carrying ester groups

New biodegradable hydrogels were obtained by a simple UV irradiation method in two steps. The first step involved functionalization of alpha,beta -pol y(N-2-hydroxyethyl)-DL- aspartamide (PHEA), a synthetic water-soluble bioco mpatible polymer, with glycidyl methacrylate (GMA) to introduce side chain reactive double bonds and ester groups. The obtained copolymer PHEA-GMA (PH G), contained 29 mol% GMA residues. The second step involved cross-linking this copolymer by UV irradiation at 313 nm to form hydrogel microparticles which were characterized by FTIR spectrophotometry, particle size distribut ion analysis and differential scanning calorimetry. Swelling measurements a t different pH values indicated a high water affinity by these hydrogels. I n vitro chemical and enzyme hydrolysis studies showed that the hydrogels we re partially hydrolyzed both at pH 1 and pH 10 by enzymes such as, esterase , pepsin and alpha -chymotripsin. The processes occurring during UV irradia tion were characterized by FTIR and H-1-NMR and rheological analyses.