By Xenocs
Combining DLS with SAXS not only overcomes the limitations inherent in each method but also bridges the gap between partial insights and a thorough characterization of the particle system. As demonstrated in this article, there are instances where neither technique alone can provide a comprehensive understanding of the sample. A group of researchers from the University of Leeds and Diamond Light Source used SAXS in combination with DLS to characterize the formation and morphological evolution of spherical block copolymer nano-objects during RAFT polymerization of diacetone acrylamide in the presence of a series of poly(dimethylacrylamide) (PDMAm) macromolecular chain transfer agents with varying degrees of polymerization (DP) [12]. DLS was used to determine hydrodynamic diameter (D h) as well as the polydispersity index (PDI) via the Stokes–Einstein equation assuming spherical and independent particles. SAXS on the other hand enabled the determination of the core diameter (D core) amongst other structural parameters such as the aggregation number, the radius of gyration of individual corona chains and the volume fraction of solvent and unreacted monomer within the core. By comparing Dh and Dcore measurements, researchers were able to understand how the corona (the outer layer of the particle) contributes to the overall size and structure of the particle.
