Berlin 2001 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 18: Poster: Polymer Blends, Heterogeneous Systems, Colloids and Nanoparticles, Interfaces, Polyelectrolytes
CPP 18.6: Poster
Mittwoch, 4. April 2001, 12:30–15:00, AT1
Phase behavior of a binary blend of chemically different symmetric diblock copolymers — •Christine M. Papadakis1, Peter Busch1, Dorthe Posselt2, and Roland Weidisch3 — 1Fakultät für Physik, Universität Leipzig, D-04103 Leipzig — 2IMFUFA, Roskilde University, DK-4000 Roskilde, Denmark — 3Fachbereich Ingenieurwissenschaften, Martin-Luther-Universität Halle-Wittenberg, D-06099 Halle
Blending diblock copolymers A-B and A-C may result in complex structures similar to those observed in A-B-C triblock copolymers. Using small-angle neutron scattering, we have investigated the phase behavior of binary blends of compositionally symmetric polystyrene-polybutadiene (S-B) and poly(d8-styrene)-poly(n-butyl methacrylate) (dS-BMA) diblock copolymers. S-B shows the classical upper critical order transition [1] and dS-BMA a lower critical order transition (LCOT) [2]. A blend with an S-B content φ = 25 % is macrophase-separated. A blend with φ = 25 % macrophase-separates at high temperatures as well, but at low temperatures, the scattering profile is consistent with a hexagonal structure of cylinders having a B-core and an S-shell immersed in a disordered matrix of dS-BMA. Also, in this sample the LCOT of the S-BMA rich domain is decreased with respect to the parent S-BMA. Under certain conditions, blends of S-B and S-BMA can thus form new structures.
[1] Papadakis, C.M. et al. Europhys. Lett. 36(1996)289 and J. Phys. II France 7(1997)1829. [2] Russell, T.P. et al., Nature 368(1994)729. Weidisch, R. et al., Macromolecules 32(1999)3405