Novel surface modification of high-density polyethylene films by using enzymatic catalysis

The surface of high-density polyethylene (HDPE) films was modified by an enzyme, soybean peroxidase (SBP). The enzymatic surface modification was performed using a peroxidase as catalyst and hydrogen peroxide as oxidizing agent. The chemical composition and morphology of HDPE surfaces were characterized by X-ray photoelectron spectroscopy, infrared spectroscopy, and scanning electron microscopy. Results showed that after enzymatic treatment, the O/C atomic ratio of HDPE surfaces increased, and new functional groups such as -CO-appeared. Moreover, the surface of treated HDPE films became rougher than untreated surfaces. The hydrophilicity of treated and untreated HDPE films was analyzed by UV-vis spectroscopy and contact angle measurements. The decreased contact angle of the HDPE with water and increased adsorption ability of the surface to a water-soluble dye clearly indicated that enzymatic treatment can significantly increase the hydrophilicity of the surfaces of HDPE films. The catalytic mechanism of SBP was also discussed.