Plasma modification of polycarbonates

We deposited protective coatings on polycarbonates from hexamethyldisiloxan e (HMDSO) and HMDSO/O-2 mixtures by the plasma enhanced CVD method. In part icular, we studied deposition rate, optical constants in UV/VIS, film compo sition and mechanical properties dependent on rf power and oxygen to HMDSO flow rate ratio. Plasma polymer HMDSO films (PP-HMDSO) showed good transpar ency in the visible and increased absorption in UV region. The optical cons tants of HMDSO/O-2 films were similar to the tabulated SiO2. In general, th e films were characterised by a relatively high content of hydrogen (22-66% ) and a carbon content below 20%. The films deposited at an oxygen-to-HMDSO flow rate ratio higher than 15 exhibited higher tensile stress and higher hardness than those prepared at ratios of 5-10. The nature of the internal stress changed to compressive for PP-HMDSO. Plasma pre-treatment of polycar bonate in argon significantly improved the film adherence, especially when low powers and short treatment times were used. (C) 2001 Elsevier Science B .V. All right reserved.