Length Characterization of Multi-Walled CNT by Capillary Hydrodynamic Fractionation (CHDF)

Abstract

Multi-walled carbon nanotubes (MWCNT) should be treated via cutting process for engineering applications because almost as-prepared MWCNT are highly entangled and aggregated. Especially, the size distribution of MWCNT after cutting process is very important factor to determine the final properties of polymer-MWCNT composite. In this study, we take a novel method for CNT characterization, a capillary hydrodynamic fractionation (CHDF), which is a traditional chromatographic method for colloid particles. The length distributions of pre-treated MWCNT by two different methods were investigated by CHDF. One is a high-power ultrasonication directly and the other is an acid treatment followed by a high-power ultrasonication. For MWCNT, retention volume apparently depends on a combination of the length, diameter and rigidity of CNTs. We found that a high-power ultrasonication renders MWCNT short into segments of a few micrometers and the additional treatment by acid solution made those much shorter and more flexible.