Dual Precursor Atmospheric Plasma Deposition of Transparent Bilayer Protective Coatings on Plastics

We demonstrate a dual organic and inorganic precursor method to deposit transparent organosilicate protective bilayer coatings on poly methyl methacrylate (PMMA) substrates with atmospheric plasma deposition in ambient air. The bottom layer was a hybrid organosilicate adhesive layer deposited with dual organic 1,5-cyclooctadiene (CYC) and widely used inorganic tetraethoxysiline (TEOS) precursors. The selection of the organic CYC precursor allowed incorporation of a carbon chain in the organosilicate adhesive layer, which resulted in improved adhesion. The top layer was a dense silica coating with high Young's modulus and hardness deposited with TEOS. The deposited bilayer structure showed ∼100% transparency in the visible light wavelength region, twice the adhesion energy, and five times the Young's modulus of commercial polysiloxane sol-gel coatings.