Fig. 2
From: Surfactant mediated liquid phase exfoliation of graphene
Sonication/Shear forces in LPE. a Broad-field TEM image showing the small flakes observed after long sonication times (180 h). b Concentration of graphene after centrifugation as a function of sonication time. The left axis shows the measured absorbance per cell length, A/l, while the right axis shows the concentration calculated using an absorption coefficient of 3620 mL mg−1 m−1. The line illustrates √t behavior. The upper axis shows the total energy output of the bath calculated using the measured power output of 23 W. a-b reproduced from ref. 34 with permission, © Wiley-VCH). c A Silverson model L5M high-shear mixer with mixing head in a 5 l beaker of graphene dispersion. d Close-up view of a DD32mm mixing head and a DD16mm mixing head with rotor (left) separated from stator. e Graphene-NMP dispersions produced by shear exfoliation. (f,g) The presence of monolayers confirmed by Raman (f) and XPS (g) spectra (NMP-shear exfoliated samples). h Wide-field TEM image of SEG nanosheets (after centrifugation). c-h reproduced from ref. 36 with permission, © Nature Publishing Group)