Dual precursor atmospheric plasma deposition of bilayer organosilicate 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 Tetraethoxysiline (TEOS) precursors. The selection of the organic CYC precursor allowed incorporation of 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.