Raman spectroscopy enabled investigation of carbon nanotubes quality upon dispersion in aqueous environments

Dispersion of high quality carbon nanotubes (CNTs) in aqueous solutions is of central importance for their potential biological and biomedical applications. Although it is now possible to obtain highly dispersed CNT solutions by means of surfactant assisted processing, organic functionalization, and mechanical mixing, a concern remains about preservation of CNTs' quality during these dispersion procedures. In this report, the authors demonstrate that by employing Raman spectroscopy, one can study changes in CNTs' quality post-dispersion. Specifically, the authors focused on mechanical mixing via sonication and quantitatively determined the effects of various parameters such as surfactants, CNTs' geometry, sonication time, and sonication method on CNTs' quality post-sonication. While not addressed here, our method could be extended to monitor CNTs' quality as a function of other parameters that could potentially compromise their quality, such as chemical functionalization or doping.