Plastic Forming of Graphene Oxide Membranes into 3D Structures.

Flat, membrane-like materials made of graphene oxide (GO) nanoflakes have extraordinary mechanical properties including high stiffness, high strength, and low weight. However, the forming of complex nonplanar structures from flat GO membranes is difficult because of the intrinsic brittleness of GO. Here we present a simple and low-cost method to plasticize vacuum-filtrated GO membranes using a cellulose additive. Compared with the pure GO membrane, the GO-cellulose membranes had a lower Young's modulus but significantly improved ductility. Using the flat GO-cellulose membrane, we successfully embossed hemispherical caps with high geometrical fidelity, smooth surfaces, and no tearing or other damages to the membrane. The stiffness of the embossed 3D structure was increased further by cross-linking with a borax solution. Hemispherical caps made of 75 wt % GO with 25 wt % cellulose slurry combining borax cross-linking showed the highest stiffness. This study extends the applications of GO membranes and allows the harnessing of their extraordinary properties to nonplanar structures.