Structure and properties of silver clusters implanted in PET by PVD sputtering for Active Packaging Applications

Active packaging is becoming the most suitable way to control and assure food safety from farm to fork. In this way, commercial products with finely dispersed nanosilver (n-Ag) particles permanently embedded in the containers are already available in the market. New plastic materials with inherent antibacterial properties can be made for this purpose by polymerization or copolymerization of new monomers or by chemical modification and/or blending of polymers. However the development of new materials by use of new monomers leads often to unacceptable high costs and changes in the bulk properties. Sometimes the obtained materials also suffer a poor thermal stability, which limits their processability. A possible alternative is to use of functional coatings, which improves surface properties of a given substrate leaving unchanged its bulk properties. This technology is limited by mechanical properties of the coating and bad adhesion to the substrates. In this work, we propose a new approach to antibacterial silver activity in packaging by implanting Ag clusters in PET (Polyethylene Terephthalate) substrates by DC sputtering technique. To improve the impermeability of the PET to the gases and water vapour, a Ag:TiOx nanofilm with homogeneous Ag nanoclusters distribution was successfully deposited by DC magnetron sputtering on PET.