Stability and dewetting of metal nanoparticle filled thin polymer films: control of instability length scale and dynamics

Mukherjee, Rabibrata ; Das, Soma ; Das, Anindya ; Sharma, Satinder K. ; Raychaudhuri, Arup K. ; Sharma, Ashutosh (2010) Stability and dewetting of metal nanoparticle filled thin polymer films: control of instability length scale and dynamics ACS Nano, 4 (7). pp. 3709-3724. ISSN 1936-0851

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Official URL: http://pubs.acs.org/doi/abs/10.1021/nn901912d

Related URL: http://dx.doi.org/10.1021/nn901912d

Abstract

We investigate the influence of gold nanoparticle addition on the stability, dewetting, and pattern formation in ultrathin polymer−nanoparticle (NP) composite films by examining the length and time scales of instability, morphology, and dynamics of dewetting. For these 10−50 nm thick (h) polystyrene (PS) thin films containing uncapped gold nanoparticles (diameter 3−4 nm), transitions from complete dewetting to arrested dewetting to absolute stability were observed depending on the concentration of the particles. Experiments show the existence of three distinct stability regimes: regime 1, complete dewetting leading to droplet formation for nanoparticle concentration of 2% (w/w) or below; regime 2, partial dewetting leading to formation of arrested holes for NP concentrations in the range of 3−6%; and regime 3, complete inhibition of dewetting for NP concentrations of 7% and above. Major results are (a) length scale of instability, where λH∼hn remains unchanged with NP concentration in regime 1 (n∼2) but increases in regime 2 with a change in the scaling relation (n∼3−3.5); (b) dynamics of instability and dewetting becomes progressively sluggish with an increase in the NP concentration; (c) there are distinct regimes of dewetting velocity at low NP concentrations; (d) force modulation AFM, as well as micro-Raman analysis, shows phase separation and aggregation of the gold nanoparticles within each dewetted polymer droplet leading to the formation of a metal core−polymer shell morphology. The polymer shell could be removed by washing in a selective solvent, thus exposing an array of bare gold nanoparticle aggregates.

Item Type:Article
Source:Copyright of this article belongs to American Chemical Society.
ID Code:96457
Deposited On:02 Jan 2013 10:05
Last Modified:02 Jan 2013 10:05

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