Dynamic fragmentation of single-walled carbon nanotubes induced by sonication

Ultrasonication is widely recognized as a highly effective means of cutting long and entangled single-walled carbon nanotubes (SWCNTs) into shorter pieces. The exact nanotube cutting mechanism, however, remains elusive. While some have attributed the fragmentation process to the microscopic domains of high temperature that attacks the surface of the SWCNTs during bubble implosion, others have suggested that the large friction forces between the liquid and the SWCNTs resulted in the scission process. In this work, we use scale-bridging molecular dynamics simulations to ascertain the exact nanotube cutting mechanisms. Results show that friction forces alone are insufficient to fracture the nanotube. However, photon irradiation during the collapse of cavitation bubbles could induce the formation of significant proportions of defects in the SWCNTs: these defects contribute to both increased frictional loads, and reduced critical shell buckling loads, ultimately leading to nanotube scission.