Mechanical properties of plasma deposited polymer coatings

Thin polymeric films have been obtained by plasma polymerisation of dimethy lsiloxane (DMSO). Such films are widely used as protective coatings on opti cal reflective surfaces and decorative parts. Thin films of polydimethylsil oxane (PDMS) have been deposited by a DC glow discharge plasma from DMSO va pour on pre-treated and untreated polycarbonate (PC) substrates, with or wi thout previous evaporation of an additional aluminium film. A subsequent pr ocess of mineralisation by immersion in an air plasma has been applied in o rder to improve the PDMS films wear resistance. Polycarbonate substrates ha ve been treated in a similar way aiming at improved adhesion of Al films. T he present paper is specially focused on the surface mechanical properties of these films. These have been measured by nanoindentation and microscratc h techniques and the improvement of the surface hardness and scratch resist ance of PDMS films and PC substrates has been assessed. (C) 2000 Elsevier S cience S.A. All rights reserved.