Plasma-enhanced chemical vapor deposition of inorganic coatings on polymeric materials using organic precursors

Summary form only given. Polymeric materials generally have lower mechanic properties than metal, metal oxides and other inorganic salts, such as hardness, stability in the air and resistance to organic solvents. High permeability to oxygen and water vapor is also a shortcoming of polymeric films when it comes to food packaging. In order to modify the properties of the polymeric materials, thin layers of inorganic coatings can be deposited by plasma techniques on the substrate surface. These coatings are expected to provide properties such as hydrophilicity, hardness, good barriers, good bio-comparability and good adhesive coatings to paints. SoftplasmaTM is a low pressure (~10 Pa) and low frequency (<0.05 MHz) plasma deposition process, which is able to deposit the coating without destroy the substrate and control the deposition of functional groups of the monomers. Tetramethoxysilane (TMOS) as organic precursor is often used for deposition of silicate. By using SoftplasmaTM and controlling the oxygen content in the media gas, we can control the properties of the silicate deposition, such as hardness due to the different carbon contents and the different lattice bonds in the deposition. By introducing phosphorus in the coating, we are able to deposit hydrophilic coatings on different substrates, like polyethylene (PE) films, polycarbonate (PC), silicon rubber, polyester. Phosphorus oxide is anyhow water soluble. In order to stabilize the phosphorus in the coating, metal oxides are introduced to the deposition system. A thin layer of Si, metal and phosphorus oxide is deposited on the substrates. Due to that P(5+)M(3+) (such as Al, Fe)O4 has the same lattice structure as SiO2, such coating is not soluble in water. Trimethylphosphite (P(OCH3)3), trimethylaluminum (Al(CH3)3) and iron pentacarbonyl (Fe(CO)5) are used as precursors in such deposition reaction. We have tested the adhesive (failure at the coating/substrate interface) and cohesive (failure within the c- ating film or the substrate) properties of the coatings and the water contact angles depending on the phosphorus content of the coatings on various substrates. The permeability of the coatings against oxygen and water vapor were tested. Beside the coatings were characterized by FT-IR, AFM (atomic force microscopy) and XPS (X-ray photoelectron spectroscopy)