Solvent assisted dispersion of graphene and its PVA nanocomposites coating: Processing and characterization

In this work, graphene is dispersed in a various solvents like dimethyl formamide (DMF), N-methyl 2-Pyrrolidone (NMP), isopropyl alcohol (IPA), dimethyl sulphoxide (DMSO). The stability of graphene in various solvents is assessed with the help of the photographic method, which reveals the IPA and NMP are the best solvents for graphene dispersion with more stability. UV–Vis-NIR spectroscopy shows the higher absorbance value of IPA dispersed graphene depicting better dispersion of graphene as compared to DMF, DMSO, and NMP. Hansen and Hildebrand solubility parameters of solvents that are nearer to graphene facilitate the dispersion of graphene in the solvent. Graphene solution using IPA as solvent is then dispersed in polyvinyl alcohol (PVA) solution to prepared spin-coated PVA nanocomposites coating over steel substrate. The PVA nanocomposites coating surface is characterized using atomic force microscopy (AFM) revealing the dispersion state of graphene in the PVA matrix. In addition, scratch testing of PVA nanocomposites coating over steel substrate shows the coefficient of friction is graphene concentration dependent in PVA matrix. Optical microscope images of scratch surfaces were showing the shearing of the edges of the grooves of graphene filled PVA nanocomposites over the steel substrate.