Morphology and gas barrier properties of thin SiOx coatings on polycarbonate: Correlations with plasma-enhanced chemical vapor deposition conditions

Plasma-enhanced chemical vapor deposition of SiOx coatings on thermoplastic s provides a viable route for production of transparent composite materials with high fracture toughness and high gas barrier properties, which are im portant considerations in the food packaging and biomedical device industri es. By examining several series of systematically varied SiOx/polycarbonate composites, we have identified design correlations between coating charact eristics (thickness, density, surface roughness, and O-2 transmission) and deposition conditions (time, power, pressure, and flow rates). Of particula r interest is the observation that the thermal activation energy for O-2 pe rmeation through these composites increases (by up to 17 kJ/mol) as their b arrier efficacy increases.