Tunable auxeticity in hydrogenated carbon nanotube origami metamaterial

Inspired by the origami architecture and the progress in the functionalization of carbon-based nanomaterials, we design a carbon nanotube origami (CNT-O) metamaterial with the assistance of hydrogenation and by utilizing molecular dynamics simulation. The mechanical properties, including stiffness, ultimate strength, failure strain, and Poisson's ratio, are systematically studied. Our findings show that the mechanical properties of CNT-O can be tuned and programmed by altering the underlying topological parameters and adopting surface functionalization. We resort to computational simulation, theoretical analysis, and experimentation to demonstrate that an extremely broad range of strain-dependent and scale-independent negative Poisson's ratio can be achieved for nanoarchitected metamaterials, mainly driven by the kinematics of the folding/unfolding in origamis. The proposed origami strategy imparts a platform for designing the next generation of low-dimensional nanomaterials (e.g., graphene and CNT) with highly tunable auxeticity.