Pattern morphology dewetting

Roy, S., Mukherjee, R. Ordered to isotropic morphology transition in pattern-directed dewetting of polymer thin films (m substrates with different feature heights. ACS Appl. Mater. Interfaces 4.5375-5385 (2012)... 

R. Mukherjee, D. Bandyopadhyay, and A. Sharma, Control of morphology in pattern directed dewetting of thin poiymer i ms. Soft Matter, 4, 2086 [2008]. 

From Holes to Drops to Toroids Conditions for the Transcription of Surface Patterns into Three-Dimensional Morphologies via Rim Instabilities in the Course of Dewetting... 

Kargupta, K., Sharma, A. Morphological self-organization by dewetting in thin films on chemically patterned substrates. J. Chem. Phys. 116, 3042-3051 (2002)... 

It has been described in previous chapters how spontaneous instabilities related to interfacial phenomena can be used to produce controlled patterns on polymer surfaces. Strategies of polymer patterning assisted by dewetting or water drop condensation were described. In this chapter we present a waterborne process based on the interaction between ions in water and hydrophobic polymer surfaces, modulated by the gases dissolved in the aqueous phase. We show how by controlling this interaction the polymer surface can be conveniently modified. In the first section of the chapter we describe some aspects of the interface between water and a hydrophobic surface. We then describe how the composition of the aqueous phase can have important consequences on the morphology of the hydrophobic surface, and then illustrate how this process can be conveniently used to modify the morphology of a hydrophobic polymer in a controlled manner. 

It is important to note that spinodal dewetting " - does not imply that the surface instability and consequent dewetting can occur only in the form of a bicontinuous structure composed of liquid ridges or "hills" and "valleys." The thin-film experiments presented here demonstrate that a rich variety of morphological patterns can evolve. 

Figure 4.4 shows a time series of optical micrographs representing the t3q)ical spatial and temporal evolution of the morphological pattern during the self-destruction and dewetting of a PDMS film. This visual information is complemented by presentation of... 

In the light of the above presentation we conclude that the self-destruction of thin polymer films is a combination of two serial processes, amplification of initial surlace fluctuations and subsequent dewetting of the underlying substrate (see Fig. 4.2). There is a finite time window during which the holes are formed, and both processes overlap. The evolution of the morphological pattern during the whole process can be summarized as follows ... 

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... 

Figure 11.7 The influence of pattern dimension on the final morphology (aligned, partially aligned and random droplet arrays) of structures resulting from dewetting of a 12 nm-thick PS film. Optical micrographs and insets show transition from the doublet state (15-12 pm stripe width), to coalescence (9 pm), confinement (6 and 3 pm), and a...

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