Computational Investigation of Large-Diameter Carbon Nanotubes in Bundles for High-Strength Materials

Carbon nanotube aerogels are interesting platforms for the manufacture of lightweight composites. To guide the development, we screen with tight-binding atomistic calculations two primary crystalline organizations of nanotubes with 1.4-4.5 nm radii and 1-3 number of walls. Calculations reveal a crossover from polygonized nanotubes with hexagonal close-packing organizations to collapsed shapes organized in stacks. The energies of the two modes are captured into a concise form, which predicts the crossover radii and domains of their dominance. The graphite-like phase formed with collapsed nanotubes allows for ∼1 TPa Young's moduli. Bundles of collapsed nanotubes emerge as natural candidates for the developmnent of ultrastrong composites.