Europhys. Lett., 73 (6), pp. 899-905 (2006)
DOI: 10.1209/epl/i2005-10475-5

The effect of surface interactions on the viscosity of polymer thin films

Chunhua Li¹, Hyunjung Kim², Jun Jiang¹, Clive Li¹, Tadanori Koga¹, Laurence Lurio³, Steve Schwarz⁴, Suresh Narayanan⁵, Heeju Lee², Young Joo Lee², Zhang Jiang⁶, Sunil Sinha⁶, M. H. Rafailovich¹ and J. C. Sokolov<sup>1

1</sup>  Department of Materials Science and Engineering, SUNY at Stony Brook Stony Brook, NY, 11794, USA
²  Department of Physics and Interdisciplinary program of Integrated Biotechnology Sogang University - Seoul, 121-742, Korea
³  Department of Physics, Northern Illinois University - DeKalb, IL, 60115, USA
⁴  Department of Physics, Queens College - Flushing, NY, 11367, USA
⁵  Advanced Photon Source, Argonne National Laboratory - Argonne, IL, 60439, USA
⁶  Departments of Physics, University of California San Diego La Jolla, CA, 92093, USA

chuli@ic.sunysb.edu
mrafailovich@notes.cc.sunysb.edu

received 14 November 2005; accepted in final form 19 January 2006
published online 11 February 2006

Abstract
We have measured the viscosity of thin polymer films as a function of film thickness using three independent techniques. The results of all methods indicated that the viscosity of the film increases about two orders of magnitude near the solid substrate. Measurements performed on split layer substrates indicated that a layer of polymer chains remained permanently adsorbed at the Si substrate. This layer was responsible for trapping subsequent layers, and propagating the effect of surface interactions to chains without direct contacts to the solid substrate. If this layer was applied prior to the rest of the film, it can screen the surface interactions and even initiate auto-dewetting of other chemically identical layers above it.

PACS
68.03.Kn - Dynamics (capillary waves).
61.30.Hn - Surface phenomena: alignment, anchoring, anchoring transitions, Surface-induced layering, surface-induced ordering, wetting, prewetting transitions and wetting transitions.
68.05.-n - Liquid-liquid interfaces.

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