Constellation, le dépôt institutionnel de l'Université du Québec à Chicoutimi

Résumé

Performance of graphene nanoplatelets depends on its dispersion quality and level of homogeneity, to this end investigating graphene dispersing approaches from different point of view will be highly applicable. In this study, we compared the effects of different surfactants—sodium dodecylsulfate (SDS), sodium dodecylbenzen sulfonate (SDBS), cetyltrimethylammonium bromide (CTAB), and nonylphenolethoxylate (NPE)—in their capacity to produce stable aqueous media containing homogeneously dispersed graphene nanoplatelets (GNPs). To compare the surfactants’ ability to produce optimal dispersion of graphene, we relied on optical characterization, i.e. UV–vis spectroscopy, optical microscopy, and turbidimetry. CTAB-containing GNP dispersion showed the highest stability and lowest graphene flake size. The character of the different surfactants led us to investigate the stability mechanisms in the aqueous dispersions. Zeta potential was measured to determine the effective surface charge of GNPs in each aqueous medium. The accordance between experimental results and theories in this regard increases the reliability of results. Hence, we evaluated the results through DLVO theory to rank the performance of surfactants more evidently. Based on zeta potential values and the height of the energy barrier in interaction energy graph, CTAB had the best performance in terms of stability and preventing GNP aggregate formation. Molecular dynamics simulation was conducted to have better understanding of interactions between different surfactants and graphene nanosheets. The performance of the surfactants was ranked in order of CTAB, SDBS, SDS, NPE. Using UV–vis spectroscopy, particle size analysis, TEM and SEM imagery, we determined that the optimal concentration of CTAB is 400 ppm.