From single-layer graphene to HOPG: Universal functionalization strategy with perfluoropolyether for the graphene family materials

Graphene functionalization offers the opportunity to modify the chemical-physical properties of graphene, therefore broadening the variety of its possible applications. In this work, single- and few-layers graphene as well as highly oriented pyrolytic graphite (HOPG) were functionalized with perfluoropolyether (PFPE) chains via a peroxide decomposition and radical reaction. Samples were prepared using different amounts of PFPE peroxide and the effects of the treatment were studied through Raman spectroscopy, grazing angle Fourier-transform Infrared spectroscopy (GA-FTIR), X-ray Photoelectron Spectroscopy (XPS) and water contact angle measurements. A coherent trend of F[sbnd]C bonds with increasing amount of peroxidic precursor was detected, attacking the sp2 reactive sites of the grains of graphene itself and generating new sp3 hybridizations. The perfluorinated chains were found to give hydrophobic properties to graphenic layers, demonstrating the functionalization route as an easy and universal strategy for the preparation of hydrophobic graphenic substrates.