title: Thermally induced alkylation of diamond.
abstract: We present an approach for the thermally activated formation of alkene-derived self-assembled monolayers on oxygen-terminated single and polycrystalline diamond surfaces. Chemical modification of the oxygen and hydrogen plasma-treated samples was achieved by heating in 1-octadecene. The resulting layers were characterized using X-ray photoelectron spectroscopy, thermal desorption spectroscopy, atomic force microscopy, Fourier transform infrared spectroscopy, and water contact angle measurements. This investigation reveals that alkenes selectively attach to the oxygen-terminated sites via covalent C-O-C bonds. The hydrophilic oxygen-terminated diamond is rendered strongly hydrophobic following this reaction. The nature of the process limits the organic layer growth to a single monolayer, and FTIR measurements reveal that such monolayers are dense and well ordered. In contrast, hydrogen-terminated diamond sites remain unaffected by this process. This method is thus complementary to the UV-initiated reaction of alkenes with diamond, which exhibits the opposite reactivity contrast. Thermal alkylation increases the range of available diamond functionalization strategies and provides a means of straightforwardly forming single organic layers in order to engineer the surface properties of diamond.
authors.affiliation: Walter Schottky Institut and Physik Department, Technische Universität München, 85748 Garching, Germany.
authors.forename: Marco
authors.initials: M
authors.lastname: Hoeb
authors.forename: Marianne
authors.initials: M
authors.lastname: Auernhammer
authors.forename: Sebastian J
authors.initials: SJ
authors.lastname: Schoell
authors.forename: Martin S
authors.initials: MS
authors.lastname: Brandt
authors.forename: Jose A
authors.initials: JA
authors.lastname: Garrido
authors.forename: Martin
authors.initials: M
authors.lastname: Stutzmann
authors.forename: Ian D
authors.initials: ID
authors.lastname: Sharp
mesh_terms: D000475:Alkenes / Q000737:chemistry; D000478:Alkylation; D018130:Diamond / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D010084:Oxidation-Reduction; D056951:Photoelectron Spectroscopy; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D000475:Alkenes; D014867:Water; D018130:Diamond