Adhesion improvements for diamond-like carbon films on polycarbonate and polymethylmethacrylate substrates by ion plating with inductively coupled plasma

An inductively coupled plasma (ICP) ion plating method using hexamethyldisiloxane (HMDSO) and oxygen reactants was employed to deposit hard diamond-Eke carbon (DLC) coatings on polycarbonate (PC) and polymethylmethacrylate (PMMA) substrates. O-2 plasma was the most effective pretreatment method for improving the adhesion of the DLC on the polymer by removing the contaminants and forming the polar functional groups on the surfaces. The adhesion of the DLC film on the PMMA substrate was always much worse than that on the PC substrate. To improve the DLC film adhesion on the PMMA substrate, interfacial layers were deposited by remote plasma polymerization in order to avoid the destruction of the functional groups in the monomer precursors. Interfacial layers deposited using HMDSO/C2H5OH mixture, methylmethacrylate and propylene oxide monomers were successful to improve the adhesion of the DLC films on the PMMA from 1A (with no interfacial layer) to 4A-5A, as measured by the X-cut method. The adhesion abilities of the interfacial layers were strongly dependent on the gas phase reactions during depositions. To understand the critical roles of the interfacial layers, the effects of the deposition conditions as well as the structures of the interfacial layers were studied. (C) 2003 Elsevier Science B.V. All rights reserved.