Fig. 4
From: Chemically modified graphene films with tunable negative Poisson’s ratios
Mechanisms of negative Poisson ratio (NPR) behaviors explained by the theoretical model. a Wrinkles, delamination of close-packed laminates (CPLs) and their ordered, disordered stacks in e-GO0 films characterized by scanning electron microscopy (SEM). b Three-dimensional reconstruction of the surface topography of e-GO0 films through optical microscopy. c Illustration of the multiscale hierarchical microstructure of a chemically modified graphene (CMG) film featuring individual graphene sheets as the fundamental building blocks, CPLs and their inter-connected network. d A 4-stick representative volume element (RVE) model, where the red configuration is stretched by force F to the blue one. e Theoretical predictions and experimental measurements of the Poisson’s ratio as a function of the angle of alignment between CPLs, α, which is related to the value of θ in the model (see Supplementary Note 4 for details). The error bars for experimental data in panel (e) indicate the standard errors (three samples were measured). Source data are provided as a Source Data file
