Ordering and Dynamics of Model Soft Spheres: Multiarm Star Polymers

Abstract

Polymer stars constitute a special case of tethered chains, in which linear macromolecules are attached by one end to a central core. In the simplest case of a single star in a good solvent, when the number of arms, f, is high, the segment density near the core is much higher than in the outside, as described by the model of Daoud and Cotton (1982) and confirmed in block copolymer micelles by small angle neutron scattering (SANS) (Förster et al, 1996); such a multiarm star polymer can be considered as a prototype spherical brush with soft colloidal character (core-shell structure). In good solvent above the overlap concentration, these stars order in a macrolattice due to the increased osmotic pressure, as shown by SANS and predicted by scaling arguments (Witten et al, 1986).