Eur. Phys. J. B 7, 411-419 (1999)
https://doi.org/10.1007/s100510050629

The segregation of poly(styrene-b-isoprene) diblock copolymers to the surface of a polystyrene melt: the effect of the ratio of block lengths

¹ Foundation for Research and Technology - Hellas, Institute of Electronic Structure and Laser, P.O. Box 1527, 711 10 Heraklion Crete, Greece
² Max-Planck-Institut für Polymerforschung, Postfach 3148, 55021 Mainz, Germany
³ Universität Frankfurt, Institut für Kernphysik, 60486 Frankfurt am Main, Germany

Received: 20 July 1998
Accepted: 11 September 1998
Published online: 15 February 1999

Abstract

The effect of the ratio of block lengths on the interfacial partitioning of poly(styrene-block-1,4 isoprene) diblock copolymers from their mixtures with polystyrene homopolymer melt is investigated utilizing a series of copolymers with almost constant molecular weight but different compositions. The concentration profile of the copolymer is measured directly using the ¹⁵N nuclear reaction analysis technique; a segregation of the diblock is found at both the air/polymer surface, due to the lower surface energy of polyisoprene, and at the substrate/polymer interface. No significant effect of the block length ratio on the free-surface excess was observed. The block molecular weights have apparently led to dangling chain conformations in the non-overlapping mushroom and in the overlapping mushroom regimes whereas the brush regime was not accessible; no indications of a real border between the two former regimes was found.