Europhys. Lett, 44 (5), pp. 606-612 (1998)
Temperature- and pressure-dependent composition
fluctuations in a
blend and diblock copolymer
H. Frielinghaus, B. Abbas, D. Schwahn and L. Willner
Forschungszentrum Jülich GmbH, Institut für
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.
The phase diagram, the Flory-Huggins parameter , 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 are larger in blends. In the diblock copolymer a constant order-disorder temperature was observed which could be explained by a compensation effect between and Gi.