Modelling approaches to the dewetting of evaporating thin films of nanoparticle suspensions

Abstract

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 focus on (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.

On the mechanism of patterning in rapidly evaporated polymer solutions: Is temperature-gradient-driven Marangoni instability responsible for the large-scale patterning?

“…Evaporation-induced self-assembled patterns were observed in different systems, including soluble silica introduced into ethanol/water solvent, aqueous solutions of colloidal nanoparticles and polymer solutions [3,[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22]. Evaporation-driven patterns demonstrate a large variety of scales, starting from the nanoscale up to large-scale patterns of 10-100 lm .…”

“…Various pathways of patterning were proposed, and the role of different factors (including mass and temperature transport, interfacial tensions and long-range forces) were discussed [1,3,7,. Nepomnyashchy et al in their recent book stated that ''the diverse physical phenomena which manifest themselves in the course of the solutions evaporation are still hardly explored" [1].…”

Influences of oscillatory structural forces on dewetting of nanoparticle-laden ultra-thin films

“…The dynamics of nanoparticles at the fluid interface, such as stability, mutual interaction and adsorption, is becoming a central research topic in micro-fabrication technique, colloid and interface science, and biological physics [8][9][10][11][12]. Free energy minimization might lead to diverse patterns of particles on the interface, which is understood as self-assembly behavior [10,13].…”

“…Free energy minimization might lead to diverse patterns of particles on the interface, which is understood as self-assembly behavior [10,13]. Imposing functionalized nanoparticles into a droplet has important effects on its wettability by changing the contact angle [11], and might be applied to detergency of oil droplet [12].…”

“…Imposing functionalized nanoparticles into a droplet has important effects on its wettability by changing the contact angle [11], and might be applied to detergency of oil droplet [12]. Recently, Thiele et al reviewed the experiments on the dewetting thin films with colloidal nanoparticle suspensions, and discussed theoretical approaches to understand this phenomenon, such as kinetic Monte Carlo, dynamical density functional theory and hydrodynamic long scale model [10]. The existence of nanoparticles or macromolecules has profound impacts on disjoining pressure.…”