Modification of oxidized graphite edge surface with poly(vinyl chloride)

Abstract

An oxidized edge surface of pyrolytic graphite (PG) has been prepared by electrochemical treatment. A thin layer of poly(vinyl chloride) (PVC) was coated on the oxidized edge surface, and the PVC-coated sample heat treated at 300, 400, and 500 °C, respectively. The influence of the PVC coating on the structural change of the oxidized edge surface of PG caused by the heat treatment was studied by laser Raman and Fourier transform-infrared attenuated total reflection spectroscopies. For the electrochemical treatment, the formation of oxygen-containing functional groups proceeds over the edge surface of PG. With increasing degree of oxidation, the functional groups are formed in the following order; hydroxyl groups, carboxyl groups, lactone groups, quinones, and acid anhydrides. Acid anhydrides are formed on the outermost surface and completely eliminated by heat treatment up to 300 °C. The other functional groups remain even after heat treatment up to 500 °C. However, the functional groups are eliminated by the PVC coating, the elimination temperature depending on the type of functional groups: quinones, lactone groups, and carboxyl groups are eliminated at 300, 400, and 500 °C, respectively. PVC coated on the edge surface is found to play an important role in the complete elimination of oxygen-containing functional groups with >C=O through heat treatment at 500 °C.