Mechanical properties of plasma deposited polymer coatings

Thin polymeric films have been obtained by plasma polymerisation of dimethylsiloxane (DMSO). Such films are widely used as protective coatings on optical reflective surfaces and decorative parts. Thin films of polydimethylsiloxane (PDMS) have been deposited by a DC glow discharge plasma from DMSO vapour on pre-treated and untreated polycarbonate (PC) substrates, with or without previous evaporation of an additional aluminium film. A subsequent process of mineralisation by immersion in an air plasma has been applied in order to improve the PDMS films wear resistance. Polycarbonate substrates have been treated in a similar way aiming at improved adhesion of Al films. The present paper is specially focused on the surface mechanical properties of these films. These have been measured by nanoindentation and microscratch techniques and the improvement of the surface hardness and scratch resistance of PDMS films and PC substrates has been assessed.