Fracture-resistant “rebar graphene” is more than twice as tough as pristine graphene. Rebar graphene, developed by the Rice lab of chemist James Tour in 2014, uses carbon nanotubes for reinforcement.
Graphene is a one-atom-thick sheet of carbon. On the two-dimensional scale, the material is stronger than steel, but because graphene is so thin, it is still subject to ripping and tearing.
Nanotube rebar diverted and bridged cracks that would otherwise propagate in unreinforced graphene. Nanotubes help graphene stay stretchy and reduce the effects of cracks. This can help flexible electronics, electrically active wearables or other devices where stress tolerance, flexibility, transparency and mechanical stability are desired.
Graphene has the desired conductivity for electronic applications.
Graphene has a native fracture toughness of 4 megapascals but rebar graphene has an average toughness of 10.7 megapascals.
Perfect graphene is believed to be one of the strongest materials, yet its resistance to fracture is much less impressive. The modest fracture toughness is thought to be related to the general brittle nature in the fracture process of graphene and its two-dimensional (2D) analogous. The brittleness also makes it extremely difficult to assess mechanical properties of 2D materials. The introduction of carbon nanotubes (CNTs) into bulk materials has proven to be a widely accepted method for toughening and strengthening materials. To date, such toughening effect of CNTs on 2D materials is largely unknown. A unique material, rebar graphene, has been synthesized that consists of CNTs embedded in graphene. In this study, by implementing a “dry” transfer technique, the freely suspended rebar graphene was systematically tested under uniaxial tension mode inside a scanning electron microscope. Our combined experiments and molecular dynamics simulations confirm that the embedded CNTs divert and bridge the propagating crack and provide a toughening mechanism for the material. Our work identifies a promising extrinsic toughening strategy for 2D materials and provides mechanistic insights into the fracture process of graphene hybrid material.