Numéro |
J. Phys. II France
Volume 4, Numéro 4, April 1994
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Page(s) | 689 - 702 | |
DOI | https://doi.org/10.1051/jp2:1994156 |
J. Phys. II France 4 (1994) 689-702
Edge dislocations in copolymer lamellar films
M. S. Turner1, 2, M. Maaloum3, D. Ausserré3, J-F. Joanny1 and M. Kunz41 Institut Charles Sadron, 6 rue Boussingault, 67083 Strasbourg Cedex, Franc
2 Cavendish Laboratory, Madingley Road, Cambridge CB3 0HE, U.K.
3 Université du Maine, URA 807, B.P. 535, 72017 Le Mans Cedex, France
4 Ciba-Geigy A.G., Basel CH4002, Switzerland
(Received 6 August 1993, revised 5 January 1994, accepted 6 January 1994)
Abstract
Thin films of symmetric diblock copolymers on a flat solid surface form lamellae parallel to the substrate. The uppermost
layer of the film may be incomplete and made of domains with a thickness equal to the lamellar period
L. We investigate these domains both theoretically and experimentally. The domain edge is associated with a dislocation in
the lamellar order which has been observed by transmission electron microscopy. We extend the linear elasticity theory of
smectic liquid crystals, to include the effect of the surface tension at the air-polymer interface. We calculate the surface
profile above a domain edge and the position (depth) of the dislocation. This profile is studied by atomic force microscopy
for polystyrene-polybutymethacrylate films. The comparison between theoretical and experimental profiles allows an estimation
of the smectic elastic constants and of the internal surface tension between the two blocks of the copolymer.
© Les Editions de Physique 1994