Anisotropy factors in small-angle scattering for dilute rigid-rod suspensions
Date
2023-06
Journal Title
Journal ISSN
Volume Title
Publisher
Journal of Applied Crystallography
Abstract
Alignment of anisotropic particles along specific orientations influences the mechanical and rheological properties of a material. Small-angle scattering techniques are widely used to probe this alignment through analysis of anisotropic two-dimensional scattering intensity patterns. The anisotropy factor is the simplest and most common quantitative parameter for describing scattering anisotropy, especially in systems containing rod-like particles, and there are several methods for calculating this factor. However, there has been no systematic study comparing these methods while also evaluating the limitations imposed by non-idealities from instrumentation or polydisperse morphology. Three of the most common methods for calculating an anisotropy factor are examined here and their effectiveness for describing the orientation of a theoretical cylinder is evaluated. It is found that the maximum theoretical value of 1 for the anisotropy factor is only accessible at certain values of scattering vector q. The analysis details recommendations for q-range selection and data binning, as these influence the calculations. The theoretical results are supported by experimental small-angle neutron scattering data for a wormlike micelle solution undergoing shear, where different calculation methods yield distinct quantifications of anisotropy.
Description
This article was originally published in Journal of Applied Crystallography. The version of record is available at: https://doi.org/10.1107/S1600576723002182
Keywords
small-angle neutron scattering, anisotropy factors, alignment, wormlike micelles, anisotropy, small-angle scattering
Citation
Rooks, Jack, Peter H. Gilbert, Lionel Porcar, Yun Liu, and Paul Butler. “Anisotropy Factors in Small-Angle Scattering for Dilute Rigid-Rod Suspensions.” Journal of Applied Crystallography 56, no. 3 (June 2023): 683–96. https://doi.org/10.1107/S1600576723002182.