Anti-bacterial nanocomposites by silver nano-coating fragmentation

Silver nanocomposites are of great interest for several fields, ranging from packaging to biomedical applications, because of their known antibacterial properties. However, their use is strongly limited by technological issues: synthesis methods of silver nanoparticles are still difficult to control in terms of size, shape and aggregation. Moreover separation of nanoparticle aggregates should occur during part manufacturing by mixing with the polymer base but this process is also troublesome. In the present study, a new process to fabricate silver nanocomposites with antibacterial properties is presented. Silver nano-films are deposited by radio frequency (RF) sputtering on polypropylene (PP) substrates. Consequently PP coated substrates are cut and inserted in a small-scale polymer mixer to produce the nanocomposite in a single step, without the need of producing nanoparticles. In fact, nanoparticles originate by the fragmentation of the nano-coating. Microscopic observations of nanocomposites revealed silver nanoclusters of different sizes. Their antibacterial activity has been verified in accordance to ISO 22196. The antibacterial activity of the nanocomposite was detected for the Escherichia coli and Staphylococcus aureus bacteria.