Surface energy of growth and seeding side of free standing nanocrystalline diamond foils

Nanocrystalline diamond foil (NCDF) is a self supporting, detached diamond layer with a thickness in the range of several 10 mu. Its freestanding character allows the investigation of the surface energy considering the growth as well as the nucleation (seeding) side. This is shown here for the first time. Contact angles of different liquids on the NCDF were measured and the surface energies were calculated using the Owens-Wendt-Rabel-Kaelble (OWRK) method. A compulsive cleaning process with liquid substances like acetone has no effect on the surface energy. Nevertheless it is recommended to clean the surface before contact angle measurements to prohibit distractions by dirt. The polar surface energy component of a NCDF after cleaning is 3 mN/m and the nonpolar component is 44 mN/m. The NCDF's surface morphology which is induced by the choice of a template's structure does not influence the surface energy. A surface oxidation by hot air or oxygen plasma is resulting in a higher surface energy and more polar components on the nucleation side of the NCDF. This effect can be used to activate the surface for applications like gluing. (C) 2013 Elsevier B.V. All rights reserved.