Diffraction features of single-walled carbon nanotubes

Single-walled carbon nanotubes (SWCNTs) are promising materials for use in multifunctional polymer composites. A special feature of SWCNTs is their tendency to aggregate into bundles with 2D close packing. The coherence of such packing leads to the appearance of diffraction maxima at small-angle X-ray scattering. Using the Debye equation for X-ray scattering, this work presents the results of a theoretical analysis of the influence exerted by various parameters of SWCNT bundles (length and diameter of SWCNTs, transverse dimensions of SWCNT bundles, distribution of diameters and the number of SWCNTs in bundles) on the position, width, and shape of these diffraction peaks. To this end, atomic models of both the individual tubes and their bundles were constructed taking into account the diameter distribution of nanotubes, which has a significant effect. The results obtained can be used to correctly interpret the experimental diffraction data.