Temperature- and pressure-dependent composition fluctuations in a polybutadiene/polystyrene polymer blend and diblock copolymer

H. Frielinghaus; B. Abbas; D. Schwahn; L. Willner

doi:doi:10.1209/epl/i1998-00516-1

DOI: 10.1209/epl/i1998-00516-1

Europhys. Lett, 44 (5), pp. 606-612 (1998)

Temperature- and pressure-dependent composition
fluctuations in a polybutadiene/polystyrene polymer
blend and diblock copolymer

H. Frielinghaus, B. Abbas, D. Schwahn and L. Willner

Forschungszentrum Jülich GmbH, Institut für Festkörperforschung
D-52425 Jülich, Germany

(received 10 June 1998; accepted in final form 15 October 1998)

PACS. 61.25Hq - Macromolecular and polymer solutions; polymer melts; swelling.
PACS. 64.60Cn - Order-disorder transformations; statistical mechanics of model systems.
PACS. 64.60Fr - Equilibrium properties near critical points, critical exponents.

Abstract:

The phase diagram, the Flory-Huggins parameter $\Gamma$ , 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 $\Gamma$ are larger in blends. In the diblock copolymer a constant order-disorder temperature was observed which could be explained by a compensation effect between $\Gamma$ and Gi.

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