Coats for suppressing the permeation of liquids and gases in resp. through a solid. Barrier coats can be created by plasma polymerisation on the basis of for example fluoropolymers or SiO2. This technique is primarily used to equip food packaging with barrier coats against water, oxygen and CO2 and fuel tanks and lines with barrier coats against hydrocarbons. A barrier coat against the permeation of fuels and chemicals can be applied to the interior of containers by means of plasma coating.
More about the systems here