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Hole Growth Instability in the Dewetting of Evaporating Polymer Solution Films

Published

Author(s)

Xiaohong Gu, D T. Raghavan, Jack F. Douglas, Alamgir Karim

Abstract

We investigate the dewetting of aqueous, evaporating polymer [poly(acrylic acid)] solutions cast on hydrophobic (polystyrene) substrates. As with typical dewetting, the evaporating films initially break up through the nucleation of holes that perforate the film, but the rapidly growing holes become unstable and form non-equilibrium growth patterns resembling Hele-Shaw viscous fingering patterns. This is natuarl since the formation of holes in thin films is similar to the injection of air or other low fiscous fluids into a highly viscous fluid confined to near two-dimensions (Hele-Shaw flow cell) where the thermodynamic driving force of dewetting is the analog of applied pressure in the flow measurement. Although dewetting patterns of this kind have been observed in water films evaporating from mica substrates, the polymer films become frozen into a stable glassy state after most of the solvent (water) has evaporated. We expect this Saffman-Taylor instability to occur generally when the rate of dewetting is sufficiently rapid and the film is viscous.
Citation
Journal of Polymer Science Part B-Polymer Physics
Volume
40
Issue
No. 24

Keywords

atomic force microscopy (AFM), dewetting, fingering patterns, Hele-Shaw flow cell, instability, spin coating

Citation

Gu, X. , Raghavan, D. , Douglas, J. and Karim, A. (2002), Hole Growth Instability in the Dewetting of Evaporating Polymer Solution Films, Journal of Polymer Science Part B-Polymer Physics, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=860424 (Accessed April 23, 2024)
Created December 1, 2002, Updated February 19, 2017