Surface modification of polyethylene terephthalate film by CO2 laser-induced graft copolymerization of acrylamide

Graft copolymerization of acrylamide onto polyethylene terephthalate (PET) using a CO2 pulsed laser was performed to improve water wettability. After laser irradiation in air, the films were placed in the aqueous solution of monomer and then heated to decompose peroxides formed onto the irradiated P ET film. Peroxide density was determined spectrophotometrically by means of the iodide method. The grafted PET surfaces were characterized by attenuat ed total reflectance infrared spectroscopy, scanning electron microscopy, a nd contact angle measurements. The electron micrographs showed that the gra fting changed the surface morphology of the PET film, which is consistent w ith the infrared spectra of the grafted films. To evaluate the surface hydr ophilicity, water drop contact angle was determined. The contact angle decr eased as a result of graft polymerization. It was also found that the hydro philicity is related to the surface morphology and grafting level. (C) 2000 John Wiley & Sons, Inc.