Highly Efficient and Predictable Noncovalent Dispersion of Single-Walled and Multi-Walled Carbon Nanotubes by Cellulose Nanocrystals

Cellulose nanocrystals (CNCs) are shown to be able to disperse in a very efficient way both single-walled (SWNTs) and multiwalled carbon nanotubes (MWNTs). Optimization of the processing parameters (sonication time and power) leads to dispersion yields as high as 70 wt % for both types of carbon nanotubes (CNTs). Such a high dispersion yield obtained in a noncovalent way with biobased nanoparticles is noteworthy and deserves further attention. Atomic force microscopy and transmission electron microscopy images suggest that the CNCs and the nanotubes form hybrids, with the stabilization of the dispersion arising from both the irreversible adsorption of the CNCs onto the nanotubes and the electrostatic repulsion between the CNCs. A quantitative model is proposed, revealing that one CNC can stabilize one SWNT three times its length in the aqueous dispersion and that more CNCs are required in the case of MWNTs. This model allows us to control the dispersion yield as a function of the processing parameters.