Wettability of hydrogenated tetrahedral amorphous carbon

The wettability and Surface energy of hydrogenated amorphous carbon films (a-C:H) elaborated by distributed electron cyclotron resonance plasma were Studied by contact angle measurements in relation to composition, structure and topography. Tetrahedral a-C:H (ta-C:H) showed relatively high water contact angle (CA) LIP to 82.3 degrees, and low Surface energy (E-s) down to 25.3 mJ/m(2). Hydrophobicity was found to increase with the intensity of the ion bombardment and with the tetrahedral character. A decrease of the dispersive component is responsible of the decrease of surface energy with substrate bias. Low mass-density polymer like a-C:H (PLC) presents also a relatively high hydrophobicity with high water CA, LIP to 76.7 degrees, and low surface energy values, down to 32.1 mj/m(2). Hydrophobicity is interpreted as resulting from a surface layer rich in sp(2)-carbon for ta-C:H and rich in C-H bonds for PLC. (C) 2008 Elsevier B.V. All rights reserved.