Accurate determination of the length of carbon nanotubes using multi-angle light scattering

We have investigated and compared various approaches for calculation and modeling (using multi-angle light scattering; MALS) in order to determine the length of carbon nanotubes (CNTs) following asymmetrical flow field-flow fractionation. Various fit methods and shape models for light scattering were considered with respect to their accuracy and robustness of the data obtained. Both single- and multi-walled CNTs (SWCNTs and MWCNTs) were analyzed to better understand these approaches in view of the different structure of CNTs (i.e., single- and multi-walled). The effect of the angular interval used for extrapolation was investigated by considering the uncertainties in the intensities of MALS at small angles. The determination of the lengths of SWCNT and MWCNT using MALS can be accurately made using two specific approaches. The ellipsoid shape model using the gyration radius as determined by the Zimm method and the rod-like fitting method were found to be most suitable for the determination of the length of SWCNTs and MWCNTs respectively.