Comparison of HMDSO and HMDSN as precursors for high-barrier plasma-polymerized multilayer coating systems on polyethylene terephthalate films

Abstract

Hexamethyldisiloxane (HMDSO)- and hexamethyldisilazane (HMDSN)-based plasma polymeric coatings are compared as elements of multilayer barrier coatings, consisting of an alternating structure of organosilicon and silicon oxide layers. Furthermore, these coatings are examined with regard to their deposition rate, critical layer thickness, surface roughness, atomic composition, and gas permeability. It is investigated how these attributes correlate in the overall barrier performance of a multilayer coating system. The concluded examinations show that HMDSN delivers best overall barrier performances as a precursor at high energy densities. For lower energy densities, the use of HMDSO is preferable. Intermediate layer thickness should not exceed six nanometers for best barrier performance in the given experiment configuration.