Surface properties of UV-irradiated poly(vinyl alcohol) films containing small amount of collagen

The surface properties of poly(vinyl alcohol) (PVA) films in the presence of 1%, 3% and 5% of collagen before and after UV-irradiation have been studied by atomic force microscopy (AFM) and by contact angle measurements. PVA films have been obtained by solvent evaporation from water solution of PVA and PVA containing small amount of collagen. After drying, the samples were irradiated with UV light wavelength λ = 254 nm in air. Surface properties before and after UV-irradiation were observed using AFM. Contact angles of two liquids: diiodomethane (D) and glycerol (G) on polymeric films were measured at constant temperature using goniometer. The results have shown that the contact angle and the surface free energy for PVA films were altered by UV-irradiation. These alterations indicate photooxidation and an increase of polarity of the surface. The comparison of surface properties of PVA films and PVA containing collagen points out that collagen is more sensitive to photooxidation than PVA and PVA/collagen blends. PVA films containing collagen easier undergo photooxidation process with formation of new polar groups than pure PVA films.