In silico assembly and nanomechanical characterization of carbon nanotube buckypaper

Abstract

Carbon nanotube sheets or films, also known as ‘buckypaper’, have been proposed for usein actuating, structural and filtration systems, based in part on their unique and robustmechanical properties. Computational modeling of such a fibrous nanostructure is hinderedby both the random arrangement of the constituent elements as well as the time- andlength-scales accessible to atomistic level molecular dynamics modeling. Here we presenta novel in silico assembly procedure based on a coarse-grain model of carbonnanotubes, used to attain a representative mesoscopic buckypaper model thatcircumvents the need for probabilistic approaches. By variation in assembly parameters,including the initial nanotube density and ratio of nanotube type (single- anddouble-walled), the porosity of the resulting buckypaper can be varied threefold, fromapproximately 0.3 to 0.9. Further, through simulation of nanoindentation, theYoung’s modulus is shown to be tunable through manipulation of nanotube typeand density over a range of approximately 0.2–3.1 GPa, in good agreement withexperimental findings of the modulus of assembled carbon nanotube films. In addition tocarbon nanotubes, the coarse-grain model and assembly process can be adaptedfor other fibrous nanostructures such as electrospun polymeric composites, highperformance nonwoven ballistic materials, or fibrous protein aggregates, facilitating thedevelopment and characterization of novel nanomaterials and composites as well as theanalysis of biological materials such as protein fiber films and bulk structures.