THE DEPOSITION OF OXYGEN CONTAINING PLASMA POLYMERS FOR USE AS PERMEATION BARRIER COATINGS

It has been found that common polymers containing oxygen have reduced hydrogen permeability. In this work we have incorporated oxygen into plasma polymer coatings as hydroxyl (OH) and carbonyl (C = O) side groups by codepositing organic vapors with H2O or H2O2. We can vary the amount of oxygen incorporated up to 25 wt% oxygen. By adjusting the amount of incorporated oxygen and the deposition parameters we can alter the hydrogen permeability of the coatings by more than three orders of magnitude. Choice of the organic precursor used has the largest effect on incorporation of OH groups into glow discharge polymerization coatings. Organics with multiple triple bonds codeposited with H2O2 produce polymer coatings with the highest oxygen content and the lowest hydrogen permeability. Organics with nitrogen such as acetonitrile codeposited with H2O2 produced plasma polymer coatings with reasonably low permeability and improved mechanical and chemical resistance. Coated membranes were exposed to radioactive tritium gas for extended periods of time and then analyzed for deterioration by remeasuring hydrogen permeability, infrared absorption, and mechanical stability.