Temperature- and pressure-dependent composition fluctuations in a polybutadiene/polystyrene polymer blend and diblock copolymer
Forschungszentrum Jülich GmbH, Institut für Festkörperforschung, D-52425 Jülich, Germany
Accepted: 15 October 1998
The phase diagram, the Flory-Huggins parameter Γ, and the Ginzburg parameter Gi of a polybutadiene/polystyrene blend and diblock copolymer were determined by small-angle neutron scattering in the pressure range of 0.1 and 200MPa. Both systems show qualitatively the same pressure dependence. The enthalpic and entropic terms of Γ are larger in blends. In the diblock copolymer a constant order-disorder temperature was observed which could be explained by a compensation effect between Γ and Gi.
PACS: 61.25.Hq – Macromolecular and polymer solutions; polymer melts; swelling / 64.60.Cn – Order-disorder transformations; statistical mechanics of model systems / 64.60.Fr – Equilibrium properties near critical points, critical exponents
© EDP Sciences, 1998