Carbon nanotube length reduction techniques, and characterisation of oxidation state using quasi-elastic light scattering

Methods to control the size reduction of carbon nanotubes (CNTs) using wet milling in conjunction with high energy sonication, and using dry milling techniques are described. The results were analysed using scanning electron microscopy and quasi-elastic light scattering techniques (i.e., dynamic light scattering, DLS). The milling studies show that dry milling is effective in reducing CNT length while wet milling is ineffective under the experimental conditions of this study. The size characterisation results indicate that there is no correlation between CNT length and DLS results as expected, since DLS theory relies on the interactions and properties of spherical particles. However there is a consistent and reproducibly discernable difference in the DLS data generated between oxidised and non-oxidised CNTs which potentially provides a means of quantitatively measuring the degree of functionalisation of oxidised CNTs.

Characterisation of oxidation state of CNTs using quasi-elastic light scattering.Figure optionsDownload as PowerPoint slideResearch highlights
► There is no correlation between CNT length and the particle size results determined using dynamic light scattering (DLS).
► A consistent and reproducible difference has been observed between DLS data for oxidised and non-oxidised CNT.
► DLS can be potentially used as a tool for quantifying functional groups attached to CNTs.