Dopamine-induced reduction and functionalization of graphene oxide nanosheets

Abstract

An experiment was conducted to show that graphene oxide (GO) nanosheets can be readily reduced by dopamine with simultaneous capping by polydopamine to provide a versatile platform for covalent grafting of functional polymer brushes. Natural graphite flakes, dopamine hydrochloride O-[2-(3- mercaptopropionylamino) ethyl]-O0-methylpoly(ethylene glycol) (thiol-terminated PEG) and O-(2-aminoethyl)-O0-[2-(bocamino ethyl]poly(ethylene glycol) (amino-terminated PEG) were used. Graphite and NaNO3 were mixed with concentrated H2SO4 in a 250 mL flask at 0°C. The temperature was kept at 5°C, and the mixture was stirred for 2 h. After that, 7.3 g of KMnO4 was added in small portions to prevent temperature rise in excess of 20°C. Then, the temperature of the reaction mixture was raised to 35±2°C, and the mixture was stirred for 30 min. Fourier transform infrared spectroscopy measurements were carried out. The appearance of a strong absorption peak confirms that PEG brushes have been grafted on the PDA-capped RGO nanosheets.