Modelling approaches to the dewetting of evaporating thin films of nanoparticle suspensions
journal contributionposted on 07.10.2014 by Uwe Thiele, Ioan Vancea, Andrew Archer, Mark J. Robbins, Lubor Frastia, A. Stannard, E. Pauliac-Vaujour, C.P. Martin, M.O. Blunt, P.J. Moriarty
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We review recent experiments on dewetting thin films of evaporating colloidal nanoparticle suspensions (nanofluids) and discuss several theoretical approaches to describe the ongoing processes including coupled transport and phase changes. These approaches range from microscopic discrete stochastic theories to mesoscopic continuous deterministic descriptions. In particular, we describe (i) a microscopic kinetic Monte Carlo model, (ii) a dynamical density functional theory and (iii) a hydrodynamic thin film model. Models (i) and (ii) are employed to discuss the formation of polygonal networks, spinodal and branched structures resulting from the dewetting of an ultrathin ‘postcursor film’ that remains behind a mesoscopic dewetting front. We highlight, in particular, the presence of a transverse instability in the evaporative dewetting front, which results in highly branched fingering structures. The subtle interplay of decomposition in the film and contact line motion is discussed. Finally, we discuss a simple thin film model (iii) of the hydrodynamics on the mesoscale. We employ coupled evolution equations for the film thickness profile and mean particle concentration. The model is used to discuss the self-pinning and depinning of a contact line related to the ‘coffee-stain’ effect. In the course of the review we discuss the advantages and limitations of the different theories, as well as possible future developments and extensions.
AJA and MJR gratefully acknowledge RCUK and EPSRC, respectively, for financial support. We acknowledge support by the European Union via the FP6 and FP7 Marie Curie schemes (grants MRTN-CT-2004005728 (PATTERNS) and PITN-GA- 2008-214919 (MULTIFLOW)).
- Mathematical Sciences