Conventional batch processing in terms of unzipping multiwalled carbon nanotubes (MWCNTs) suffers from discontinuity, safety and environmental issues, reproducibility, and limited scalability. We have established a continuous-flow, scalable, and safe process for unzipping MWCNTs, achieving a yield of 75% under flow conditions, without the need for any auxiliary reagents. This involves using a mild oxidant, aqueous hydrogen peroxide, and harnessing the mechanical energy in a vortex fluidic device (VFD) while operating at ambient temperature. The physical properties of the fabricated unzipping MWCNTs were investigated by scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, powder X-ray diffraction, and Raman spectroscopy. This scalable, continuous-flow VFD-enabled fabrication method for unzipping MWCNTs unveils the power of a fluidic vortex confined in a thin film of liquid for nanocarbon structural re-formation and functionalization.

Graphene oxide (GO) and fullerene C70 form architected-like C70/GO structures in high yield under continuous flow processing in a vortex fluidic device (VFD). The composite material forms within high-shear regimes in the thin film microfluidic platform, in the absence of surfactants, and indeed in the absence of any auxiliary substances. The structures form on intense micromixing of an o-xylene solution of C70 and a colloidal suspension of GO in dimethylformamide (DMF) at ambient conditions, with the liquids delivered through jet feeds at the same flow rate to the hemispherical base of the rapidly rotating quartz tube in the VFD, which is tilted at 45°. The particle sizes range from 0.5 to 3 μm, with their structure and properties explored using scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, X-ray powder diffraction, and Raman spectroscopy. The mechanism of formation of the architected-like structures is consistent with the general model of fluid flow in the VFD and arises from localized high-shear temperature regimes driving desolvation as the nucleation and growth step for crystallizing the fullerene component, which are then capped with GO.