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

Plasma-enhanced chemical vapor deposition of SiOx coatings on thermoplastics provides a viable route for production of transparent composite materials with high fracture toughness and high gas barrier properties, which are important considerations in the food packaging and biomedical device industries. By examining several series of systematically varied SiOx/polycarbonate composites, we have identified design correlations between coating characteristics (thickness, density, surface roughness, and O2 transmission) and deposition conditions (time, power, pressure, and flow rates). Of particular interest is the observation that the thermal activation energy for O2 permeation through these composites increases (by up to 17 kJ/mol) as their barrier efficacy increases.