Structural and mechanical properties of partially unzipped carbon nanotubes

We report molecular dynamics simulations of structural and mechanical properties of partially unzipped carbon nanotubes. Our results show that in the absence of edge passivation, partially unzipped carbon nanotubes are unstable with rising temperature depending on the geometry of cutting. When the length-to-width ratio of the graphene segment is not sufficiently large, the dangling bonds at the cutting front tend to reconnect to each other and form back to carbon nanotube structure; otherwise the structures roll up at the graphene end due to the competition of bending stiffness between longitudinal direction and transverse direction. When the graphene edges are hydrogen saturated, the self-healing behavior is suppressed. Tensile tests show that partially unzipped carbon nanotubes exhibit brittle fracture behavior, with a Young's modulus around 700 GPa, which is comparable to that of carbon nanotubes and graphene.