Fig. 3.

Scaling of mechanical properties from single layers to multilayer films. a Elastic moduli of single-layer pristine and etched GO sheets and the corresponding multilayer films. Error bars represent SD. b Percentage reduction of the elastic moduli of GO sheets as etching time increases, showing that multilayer films are much more tolerant to etching than single layers. SEM fractographs (i.e., images of the fracture surfaces) of multilayer films of c pristine, d 1-h-etched, e 3-h-etched, and f 5-h-etched GO sheets