Numéro |
J. Phys. II France
Volume 5, Numéro 3, March 1995
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Page(s) | 377 - 396 | |
DOI | https://doi.org/10.1051/jp2:1995139 |
J. Phys. II France 5 (1995) 377-396
Surface Topography of Symmetric and Asymmetric Polyolefin Block Copolymer Films
Navjot Singh, Andrew Kudrle, Mohan Sikka and Frank S. BatesDepartments of Chemical Engineering and Materials Science, University of Minnesota, Mineapolis, MN 55455, U.S.A.
(Received 13 September 1994, accepted 28 November 1994)
Abstract
Finite film thickness constraints result in the formation of islands and holes on the surface of block copolymer films when
the film thickness deviates from a conformal number of layers. This paper describes a comprehensive study of surface topography
in model polyolefin diblock copolymers. We present results on the evolution of surface topography from the spun cast state,
changes in the topology accompanying the thermal expansion/contraction of the film during annealing, and the influence of
internal microstructure on the long term stability of the surfaces. Two distinct mechanisms of evolution and coarsening of
islands and holes from the as cast state were observed. In one case the islands slowly nucleate and grow, while the other
mechanism is characterized by a spontaneous evolution of surface structure followed by rapid coarsening. One of the most significant
results of this work is the identification of a distinct asymmetry in the long term stability of the surface topography with
respect to the block copolymer composition. Diblock copolymers containing a majority of the wetting component form islands
and holes more readily, while those having a minor fraction remain flat for long periods of time (i.e., months) after annealing.
© Les Editions de Physique 1995