Surface Instability and Pattern Formation in Thin Polymer Films

Surface Instability and Pattern Formation in Thin Polymer Films 

Rabibrata Mukherjee, Ashutosh Shamta, and Ullrich Steiner 

A third approach which is gaining significant attention as a viable patterning technique, particularly in the context of liquid and soft solid thin films, is based on the 

Generating Micro- and Nanopattems on Polymeric Materials. Edited by A. del Campo and E. Arzt Copyright 2011 WILEY-VCH Verlag GmbH Co. KGaA, Weinheim ISBN 978-3-527-32508-5 

The different mechanisms that may lead to instabilities in thin polymer films can be broadly subdivided into two major categories instability resulting from the inherent dynamics of the system and instability triggered by an external field. 

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Mukherjee, R., Sharma, A., Steiner, U. Surface instability and pattern formation in thin polymer films. In del Campo, A., Arzt, E. (eds.) Generating Micro- and Nanopattems on Polymeric Materials. Wiley-VCH, Weinheim (2011)... 

I 7 7 Surface Instability and Pattern Formation in Thin Polymer Films... 

Dewetting experiments by Reiter [59-61] and subsequently by many others [62-66, 68-75,92-128,137-164] revealed the morphological evolution, self-organization, and pattern formation in thin polymer films. In most experiments the onset of instability is with the form of an undulation of the film surface (Figure 11.1a) [62] or the appearance of fairly equally sized but random collection of holes (Figure 11.1b) [59,60]. The mean... 

In addition, patterns created by surface instabilities can be used to pattern polymer films with a lateral resolution down to 100 nm [7]. Here, I summarize various possible approaches that show how instabilities that may take place during the manufacture of thin films can be harnessed to replicate surface patterns in a controlled fashion. Two different approaches are reviewed, together with possible applications (a) patterns that are formed by the demixing of a multi-component blend and (b) pattern formation by capillary instabilities. 

The formation and replication of patterns into polymer films using instabilities is a new contribution in the field of soft lithography, which typically requires the mechanical contact between a patterned master and the resist. Two classes of instabilities were discussed. The demixing of two incompatible polymers leads to a well known spinodal pattern. In thin films, this structure formation process can be guided by a pattern in surface energy. 

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