Covalent Grafting of Organic Layers on Sputtered Amorphous Carbon:  Surface Preparation and Coverage Density

Abstract

The covalent attachment of ester-, pyridine-, and ferrocene-functionalized organic layers to amorphous carbon surfaces, grown by graphite sputtering in Ar−H2 mixtures, is reported. The surface modification is based on a low temperature (160 °C) liquid-phase process. Thermally assisted grafting of linear alkenes is investigated by means of X-ray photoelectron spectroscopy (XPS), atomic force microscopy, and contact angle measurements. The beneficial role of surface oxygen removal by argon ion sputtering or thermal treatment prior to the ester grafting step is also discussed. Careful XPS data analysis provides a quantitative estimate of the density (0.2−4.3 × 1014 cm-2) of attached molecules as a function of surface preparation. The large packing density has been confirmed by the voltammetric response of a ferrocene-functionalized carbon surface.

Covalent modification of graphitic carbon substrates by non-electrochemical methods

“…McCreery's study [65] described above provides convincing evidence for the formation of covalently attached monolayers through thermal reaction with alkynes and alkenes with PPF, and the results of Godet and co-workers obtained at amorphous carbon support that conclusion [66,67]. The mechanism of the reaction is not clear however.…”

“…In a second example of the thermally-assisted reaction of an alkene with a graphitic carbon substrate, Godet and co-workers used amorphous carbon films, grown using plasma decomposition of methane and graphite sputtering in Ar-H 2 [66,67]. After sputtering, films were subjected to various times of argon ion bombardment and thermal annealing under ultrahigh vacuum, giving eight distinct surfaces with oxygen atomic percent ranging from 0.8 to 5.8 [67].…”

“…After sputtering, films were subjected to various times of argon ion bombardment and thermal annealing under ultrahigh vacuum, giving eight distinct surfaces with oxygen atomic percent ranging from 0.8 to 5.8 [67]. Reaction with ethyl undecylenate was carried out overnight in the neat liquid alkene under an inert atmosphere at 120 or 160 ºC.…”

Silicon and Silicon-Related Surfaces for Biosensor Applications

“…The reaction forms new carbon-carbon bonds, ensuring a robust grafting of monolayers. The same modification can be applied to amorphous carbon [Ababou-Girard, et al, 2007& Ababou-Girard, et al, 2006. Functional molecules, including DNA could be grafted in this way to diamond surfaces [Knickerbocker, et al, 2003] and the hybridization with complementary DNA strands could be monitored on the surfaces.…”

Determination of surface amine groups on amorphous carbon nitride thin films using a one step covalent grafting of a redox probe

“…A major contribution to this latter is aimed at exploiting their surface as a starting platform for various molecular architectures in view of various applications such as electrochemical or bio-sensors, molecular electronics or coatings with special physical or chemical properties [1][2][3]. As an example and besides glassy carbon or raw carbon materials (such as graphite), thin films of boron doped diamond (BDD) have been widely investigated in this research field due to their remarkable physical properties: mechanical resistance, chemical stability, biocompatibility and electronic conductivity [4].…”