Vertically aligned laser sliced MWCNTs.

Applications of multi-walled carbon nanotubes (MWCNTs) benefit from the availability of specific lengths of the material while keeping the outer walls pristine, for example, for applications requiring vertically aligned tubes. To this end, a simple and effective continuous flow 'top down' process to control the length of sliced MWCNTs has been developed using a vortex fluidic device (VFD) coupled with a 1064 nm pulse laser, with the process in the absence of chemicals and any auxiliary substances. Three different length distributions of the sliced MWCNTs, centered at 75 ± 2.1 nm, 300 ± 1.8 nm and 550 ± 1.4 nm, have been generated with the length depending on the VFD operating parameters and laser energy, with the processing resulting in a decrease in side wall defects of the material. We also show the ability to vertically self assemble short MWCNTs on a silicon substrate with control of the surface density coverage using a simple dipping and rinsing method.