Preparation of zinc oxide coated polypropylene film by DBD plasma treatment for antibacterial improvement

Abstract

Generally, the aim of using food packaging is to preserve food products. However, microbial contamination is able to cause food deterioration. Therefore, the antimicrobial substances are often incorporated into packaging materials. In this work, zinc oxide (ZnO) coated polypropylene (PP) film was prepared with the aid of dielectric barrier discharge (DBD) plasma treatment. The surface hydrophilicity of PP film was increased after DBD plasma treatment due to the presence of oxygen containing functional groups on the plasma-treated PP surface. In addition, the surface roughness of the plasma-treated PP film increased with increasing treatment time. The DBD plasma treatment did not affect the mechanical properties of the PP film. The optimum DBD plasma treatment time was 10 s. The plasma-treated PP film was further immersed in zinc nitrate solution before being converted to zinc oxide particles by reacting with sodium hydroxide. The highest amount of zinc oxide on PP film was 0.26 wt.% The ZnO-loaded plasma-treated PP film possessed high antibacterial activity against both gram-negative Escherichia coli and gram-positive Staphylococcus aureus.