STRUCTURE AND INTERACTIONS IN TETHERED-CHAIN SYSTEMS

The interface curvature has important effects on the structure and interactions in tethered-chain systems. As the interface is curved, the layer density profile changes from a convex parabolic shape to a concave power law. This change in structure affects the interlayer interactions. Spherical diblock copolymer micelles form a model system to vary the interface curvature. Self-consistent mean-field (SCF) theory and small-angle neutron scattering (SANS) from polymeric micellar systems are combined to study these changes. Dilute solution measurements characterize the micellar physical properties. The measured coronal radii of gyration are consistent with the mean-field calculations. The SCF theory is used to calculate interparticle pair potentials and combined with the Rogers-Young closure to the Ornstein-Zernike equation to compare with measured static structure factors S(q) from concentrated micellar suspensions We find excellent agreement between theoretical and measured S(q) for a moderately curved system and good agreement for a star polymer-like system except at the highest core-volume fractions. The SCF potentials qualitatively illustrate the influence of interface curvature on the structure of ordered micellar lattices, both face-centred cubic (fcc) and body-centred cubic (bcc), obtained at high polymer concentrations.