title: Nanoscale investigation of the structural and chemical changes induced by oxidation on carbon black surfaces: a scanning probe microscopy approach.
abstract: Scanning tunneling microscopy (STM) and noncontact tapping mode atomic force microscopy (AFM) have been employed to study on a local scale the structural and, for the first time, the chemical changes of carbon black (CB) particles following plasma oxidation. STM imaging of the pristine, untreated particles revealed a relatively ordered structure of tiny crystallites with a few amorphous regions. After plasma treatment, the crystallites were no longer observed and the CB particle surface exhibited a noticeable and ubiquitous increase in atomic-scale disorder. Phase contrast images obtained with noncontact tapping mode AFM indicated that the untreated CB particles were essentially hydrophobic as a pristine basal surface of graphite, but with occasional hydrophilic patches. By contrast, their plasma-treated counterparts displayed enhanced hydrophilicity as a result of the introduction of oxygen onto the CB surface, the presence of which was evidenced by X-ray photoelectron spectroscopy, but most significantly, such enhancement was observed to be quite uniform at a local scale of individual particles. The possibility of investigating on a very local scale the chemical behavior of oxidized CB particles should be useful for the control and optimization of their dispersion properties in different systems.
authors.affiliation: Instituto Nacional del Carbón, CSIC, Apartado 73, 33080 Oviedo, Spain.
authors.forename: J I
authors.initials: JI
authors.lastname: Paredes
authors.forename: M
authors.initials: M
authors.lastname: Gracia
authors.forename: A
authors.initials: A
authors.lastname: Martínez-Alonso
authors.forename: J M D
authors.initials: JM
authors.lastname: Tascón