Thin antimicrobial silver, copper or zinc containing SiO_x films on wood polymer composites (WPC) applied by atmospheric pressure plasma chemical vapour deposition (APCVD) and sol–gel technology

Microbial colonization of wood and wood polymer composites (WPC) by bacteria and mould can cause aesthetic damage, negative impact on mechanical properties or even health hazards. This work investigated the structural morphology, elemental composition and antimicrobial properties of thin functional silicon oxide films deposited on WPC using atmospheric pressure chemical vapour deposition (APCVD) and sol–gel technology. Scanning electron microscopy results indicated the creation of flat, thin and closed films on top of the surface of this material. By embedding of active agents such as silver, copper or zinc, the APCVD films became slightly rougher. The corresponding sol–gel-films showed a certain number of cracks. The elemental composition of the films was investigated by X-ray photoelectron spectroscopy and depth profiling indicating the integration of active agents into the created SiO_x film matrices. Moreover, the possibility to generate combinations of active agents in one layer could be demonstrated. BacTiter-Glo^® tests as a part of antibacterial investigations showed strong bactericidal properties for silver and copper as well as sufficient properties for zinc-containing layers against Escherichia coli. Antimycotic effects on mould strains Aspergillus niger, Paecilomyces variotii, Penicillium funiculosum and Trichoderma viride were low for films containing only one active agent. Significant improvements in activity were achieved by the combination of these active agents.