Small-angle neutron scattering investigation of correlations in charged macromolecular and supramolecular solutions

Abstract

An overview of an important aspect of SANS research on charged colloidal suspensions is presented. These systems are characterized by pronounced interparticle correlations resulting from a strong and long-range double-layer interaction between macroions (i.e. the charged colloidal particles). Emphasis is laid on the use of simple statistical mechanical models, which are applicable in treating SANS data, that take into account the double-layer interaction. Examples are taken from work on dense protein solutions, ionic micellar solutions and protein-detergent complexes in aqueous solutions. Spherical and rod-like particles are considered. Polydispersity effects are taken into account whenever possible. In the case of rod-like systems, alignment by a shear gradient and the consequent analysis of two-dimensional SANS intensity distributions are briefly discussed.

A phenol-induced structural transition in aqueous cetyltrimethylammonium bromide solution

“…A decreased surface charge of the micelles and screening of interaction by electrolytes leads to a decrease in the head group area of surfactants, which in turn increases the packing parameter of the micelles. In other words, decreased head group repulsion favors closer packing of the surfactant monomers and hence induces a sphere-to-rod transition in micelles [27][28][29].…”

Viscoelastic micellar water/CTAB/NaNO3 solutions: Rheology, SANS and cryo-TEM analysis

“…This indicates the presence of repulsive intermicellar interaction between the positively charged CTAB micelles. The correlation peak usually occurs at Q max ∼ 2π /d, where d is the average distance between the micelles and q max is the value of Q at the peak position [35]. With the addition of NaNO 3 this correlation peak broadens as well as shifts to lower Q values.…”

A 2-dimensional small-angle X-ray scattering study of the microphase-separated morphology exhibited by thermoplastic polyurethanes and its response to deformation

“…The Percus-Yevick model has been used to fit smallangle neutron scattering (SANS) data from liquid metals [52], solutions of charged macromolecules [53] and microemulsions [54]. Kinning and Thomas [51] used the model to fit SANS data from spherical domains in a microphase-separated block copolymer, while Krakovský et al [27] and Chen-Tsai et al [39] used it to describe SAXS data from PU formulations.…”