A rapid quantitative protocol for measuring carbon nanotube degree of dispersion in a waterborne epoxy–amine matrix material

The available literature makes it very clear that accurate measurements of carbon nanotube dispersion quality are very complicated and the typical characterization is neither simple nor reliable. Most methods to quantify carbon nanotube dispersion reported in the literature require investigator-chosen assumptions or software interpretations that are impractical at best and misleading at worst for facile application. Herein, we report on the use of visible light absorption-based method(s) and validate that these were quantitative for discerning dispersibility differences for MWCNTs with three distinct surface chemistry modifications and concentration levels blended with polymeric materials. Ultimately, the dispersion quality was quantified via the trendline slope of the thickness-normalized absorbance values as a function of MWCNT concentration. Extremely poor dispersions were represented by statistically insignificant slope trendlines. Our data revealed that hydroxyl surface modification increased MWCNT dispersibility by a factor of ~2.8 and ~2.6 compared to the as-received MWCNT formulations via the absorption and the blackness methods, respectively. These results support and quantifiably validate that simple optical blackness values directly measured the degree of dispersion for MWCNTs in coatings applied to substrates, and our data support that this is a simple and effective quality control metric.