Structure, thermophysical, antimicrobial, and genotoxic properties of silver-containing nanocomposites film, obtained by sputtering deposition

To create film materials with antimicrobial properties, silver nanoparticles are widely used, which are introduced, in particular, into polymer matrices. In this work, a mixture of polylactide-polycaprolactone polymers, taken in a mass ratio of 80–20, was used as a polymer base. These studies will further contribute to the development of new safe materials, particularly in creating packaging materials for food products, which is undoubtedly an urgent problem today. The work aimed to create silver-containing polymer composites based on a mixture of polylactide and polycaprolactone by vacuum deposition of silver nanoparticles on the surface of the polymer matrix and to study the structure, morphology, thermophysical, antimicrobial, and genotoxic properties of the obtained composites. Silver nanoparticles were sputtered on the surface of the PLA-PCL polymer mixture using an FC-1100 ion sputtering device (JEOL, Japan) for 1, 3, and 5 min. The thickness of the films was 110 μm. The structure, morphology, thermophysical, antimicrobial, and genotoxic properties of composites formed by sputtering silver nanoparticles on the surface of the polymer were studied using wide-angle X-ray scattering on a device XRD-7000 (Shimadzu, Japan), transmission electron microscopy (TEM) (a JEM-1230 JEOL, Japan), thermogravimetric analysis (a TGA Q50) (TA Instruments, USA), differential scanning calorimetry (a DSC Q2000) (TA Instruments, USA), as well as antimicrobial and genotoxic tests. Using X-ray structural analysis, it was found that the original polymers are characterized by a semi-crystalline structure, and the presence of metallic silver on the surface of the polymer was confirmed. It is shown that a layer of silver particles of about 425 nm is formed on the surface of the PLA-PCL mixture for a sputtering duration of 5 minutes. According to the results of differential scanning calorimetry, it has been found that when sputtering silver particles on the surface of polymers, the degree of crystallinity increases from 35 to 39 %, and the melting temperature Tm increases from 168 to 169–170 °C. At the same time, the influence of the metallic layer of silver on the amorphous phase of the polymer was not recorded. The antimicrobial activity of PLA-PCL-Ag samples with a spraying duration of 3 and 5 min against S. aureus and E. coli microorganisms was revealed. It was found that the studied samples did not show a toxic effect.