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Affrossman, S. ; Stamm, M.
The effect of molecular weight on the topography of thin films of blends of Poly(4-bromostyrene) and Poly(styrene)

Blends of polystyrene and poly(4-bromostyrene) phase-separate during spin-casting onto silicon wafers to give a thin film with islands of poly(4-bromostyrene) in a sea of polystyrene. Variation of the molecular weights of the blend components shows that the poly- (4-bromostyrene) and polystyrene influence the film structure in different ways. For poly(4-bromostyrene) of a given molecular weight, the ratio of the observed feature height to the overall film thickness remained constant as the film thickness increased. Moreover, the mean height of the topographical features was independent of the polystyrene but decreased with the molecular weight of the brominated polymer. It is concluded that the substrate-poly(4-bromostyrene) interaction dominates the formation of topography and consequently, though the islands are poly(4-bromostyrene), the mean height of the topographical features is greater the lower the molecular weight of the brominated polymer. The polystyrene has a secondary role, altering the thermodynamics or viscosity of the blend, thereby controlling the number of islands formed: the higher the molecular weight of the polystyrene the greater the number of islands.

Source
Colloid and Polymer Science 278

Pages
888-893

DOI
http://dx.doi.org/10.1007/s003960000359

Published
November 2000
 
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Nanostructured Materials