Unusual Dewetting of Thin Polymer Films in Liquid Media Containing a Poor Solvent and a Nonsolvent

Title
Unusual Dewetting of Thin Polymer Films in Liquid Media Containing a Poor Solvent and a Nonsolvent
Author(s)
주상우린수Ashutosh Sharma[Ashutosh Sharma]Hui Liu[Hui Liu]Tongfei Shi[Tongfei Shi]
Keywords
GLASS-TRANSITION DYNAMICS; POLYSTYRENE FILMS; PATTERN-FORMATION; SURFACE MOBILITY; INSTABILITY; MORPHOLOGY; SLIPPAGE; ARRAYS
Issue Date
201412
Publisher
AMER CHEMICAL SOC
Citation
LANGMUIR, v.30, no.49, pp.14808 - 14816
Abstract
We investigate the control of pattern size and kinetics in spontaneous dewetting of thin polymer films (polystyrene) that are stable to thermal annealing by annealing in a poor solvent (acetone)/nonsolvent (ethanol or n-hexane) liquid mixture. Dewetting occurs by the formation and growth of circular holes that coalesce to form droplets. The influence of the nature and the volume fraction of the nonsolvents on the contact angle of polymer droplets, number density of holes, and the kinetics of holes formation and growth is studied. Addition of ethanol greatly increases the hole density and slows down the kinetics substantially, while affecting only a small change in wettability. n-Hexane addition shows an interesting nonmonotonic response in decreasing the hole density and contact angle in the volume fraction range of 0-0.3 but an opposite effect beyond that. Although the two nonsolvents chosen cannot by themselves induce dewetting, their relative affinity for the solid substrate vis-a-vis acetone can strongly influence the observed dewetting scenarios that are not understood by the existing theoretical considerations. n-Hexane, for example, has great affinity for silicon substrate. In addition to the changes in wettability, viscosity, and film interfacial tension engendered by the nonsolvents, the possibility of the formation of adsorbed liquid layers at the substrate-polymer interface, which can modify the interfacial friction and slippage, needs to be considered.
URI
http://hdl.handle.net/YU.REPOSITORY/30339http://dx.doi.org/10.1021/la503319w
ISSN
0743-7463
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공과대학 > 기계공학부 > Articles
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