Structure factors effects in small-angle scattering from block copolymer micelles and star polymers

Abstract

Expressions for the form factor of a block copolymer micelle model with a spherical core and Gaussian polymer chains attached to the surface have previously been given by Pedersen and Gerstenberg [Macromolecules 29, 1363 (1996)]. In the present work the inclusion of particle interference effects in the intensity expression in terms of a structure factor is described. The results are derived assuming that the effective interaction between the particles is known, i.e., the structure factor related to the center–center distribution is assumed to be known. The derived expression for the intensity is not a simple product of the form factor and the structure factor, which has the important consequence that the effective structure factor depends on the relative scattering contrast of the core and the corona of polymer chains. The structure factor effects for Gaussian star polymers are described by the same expression for a vanishing core radius. The influences of chain self-avoidance and chain–chain interactions are discussed.