Interfacial resistance and length-dependent transport diffusivities in carbon nanotubes

We investigate the transport diffusion of methane at 300 K in a series of short (10, 10) carbon nanotubes with length of up to 100 nm, using a novel equilibrium molecular dynamics simulation (EMD) method. The calculated transport diffusivities for methane in the short CNTs were validated by gravity-driven nonequilibrium molecular dynamics (NEMD) simulations. Because of the dominant interfacial resistance, which collectively accounts for the entrance and exit interfacial barriers, the transport diffusivities of methane in the finite CNTs are generally 2–3 orders of magnitude lower than those in an infinitely long CNT and depend significantly on the tube length. The EMD simulations show that interfacial resistance is the major source of resistance to transport, and that the ratio of the interfacial resistance to the overall resistance decreases with increase in the length of the CNTs. Significant correlation between the motion of methane near the interfaces and that deep inside the CNT was found, showing th...