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Effect of the Molecular Weight of AB Diblock Copolymers on the Lamellar Orientation in Thin Films: Theory and Experiment
Author(s) -
Potemkin Igor I.,
Busch Peter,
Smilgies DetlefM.,
Posselt Dorthe,
Papadakis Christine M.
Publication year - 2007
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.200600764
Subject(s) - lamellar structure , copolymer , perpendicular , polybutadiene , materials science , orientation (vector space) , lamellar phase , polystyrene , layer (electronics) , surface tension , polymer chemistry , chemical physics , composite material , chemistry , thermodynamics , geometry , physics , polymer , mathematics
We propose a theoretical explanation of the parallel and perpendicular lamellar orientations in free surface films of symmetric polystyrene‐ block ‐polybutadiene diblock copolymers on silicon substrates (with a native SiO x layer). Two approaches are developed: A correction to the strong segregation theory and a qualitative analysis of the intermediate segregation regime. We show that the perpendicular orientation of the lamellae formed by the molecules of high molecular weight is stabilized by A–B interfacial interactions. They are weaker in the case of the perpendicular orientation of the lamellae, whereas the surface tension coefficient of the A–B interface decreases with the increase of the molecular weight.