Stability and Dewetting of Thin Liquid Films

Jacobs, Karin; Seemann, Ralf; Herminghaus, Stephan

doi:10.1142/9789812818829_0010

Cited by 28 publications

(43 citation statements)

References 66 publications

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“…Previous experiments, indeed, identified a significant influence of the longrange component of the interaction potential on the dewetting of thin liquid films [6,7], their liquid front profiles [8,9] and the mesoscopic organization of magnetic nanocrystals [10]. Recently, a similar influence was detected on the adsorption kinetics of proteins [11][12][13] and the adhesion of bacteria [14].…”

Section: Introductionmentioning

confidence: 83%

Macroscale adhesion of gecko setae reflects nanoscale differences in subsurface composition

Loskill

Puthoff

Wilkinson

et al. 2013

J. R. Soc. Interface.

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Surface energies are commonly used to determine the adhesion forces between materials. However, the component of surface energy derived from long-range forces, such as van der Waals forces, depends on the material's structure below the outermost atomic layers. Previous theoretical results and indirect experimental evidence suggest that the van der Waals energies of subsurface layers will influence interfacial adhesion forces. We discovered that nanometre-scale differences in the oxide layer thickness of silicon wafers result in significant macroscale differences in the adhesion of isolated gecko setal arrays. Si/SiO 2 bilayer materials exhibited stronger adhesion when the SiO 2 layer is thin (approx. 2 nm). To further explore how layered materials influence adhesion, we functionalized similar substrates with an octadecyltrichlorosilane monolayer and again identified a significant influence of the SiO 2 layer thickness on adhesion. Our theoretical calculations describe how variation in the SiO 2 layer thickness produces differences in the van der Waals interaction potential, and these differences are reflected in the adhesion mechanics. Setal arrays used as tribological probes provide the first empirical evidence that the 'subsurface energy' of inhomogeneous materials influences the macroscopic surface forces.

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Section: Introductionmentioning

confidence: 83%

Macroscale adhesion of gecko setae reflects nanoscale differences in subsurface composition

Loskill

Puthoff

Wilkinson

et al. 2013

J. R. Soc. Interface.

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“…We have mentioned that physical experiments have shown that a nearly uniform layer of a thin film will break up due to instabilities [2,6]. Our first step will be to try to model this dewetting.…”

Section: Formulation Of the Thin Film Problemmentioning

confidence: 99%

“…This particular phenomenon is called dewetting, and it occurs frequently in dynamic mechanical systems. For example, experiments on different polymer solutions [2,6] have attempted to pin down the peculiar nature of dewetting. More simply however, this behavior is also exhibited in everyday materials such as printing ink, paint, and lubricant.…”

Section: Introductionmentioning

confidence: 99%

Statistical Analysis of Simulations of Coarsening Droplets Coating a Hydrophobic Surface

Semko¹

2010

SIURO

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Thin layers of slow-moving, viscous fluid which coat hydrophobic surfaces are shaped by the competing forces of disjoining pressure and surface tension. These forces form the fluid layer into an array of discrete droplets separated by an ultra thin layer. However, the droplet array is unstable, and the droplets will interact with one another. To determine the structure and properties of steady droplets, we use the Reynolds' PDE in one dimension and phase-plane methods. We can then analyze the unstable droplet system by utilizing paired ODEs. Numerical solutions show how the droplets interact to produce movement and mass exchange, giving rise to coarsening events which reduce the number of droplets in the system. These events occur when a droplet collapses into the ultra thin layer or when two droplets collide, and thus, merge. Using numerical simulations and analysis of their results, we aim to gain a better understanding of the dynamics of this system including the factors that influence coarsening events such as system parameters and initial conditions.

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“…Returning to the discussion of thin films, we note that such films are often unstable due to destabilizing liquid-solid interaction forces. The nature of these instabilities has been considered extensively in a variety of settings including polymer films [8,18,19], liquid crystal films [20][21][22], as well as liquid metals [23,24] (see also [25,26] for excellent reviews of this topic). The instability development leads to many questions even in relatively simple settings.…”

mentioning

confidence: 99%

“…We will focus on particular examples of nematic liquid crystal films and, to a smaller extent, on polymer films; however, the main features of our results are general, and will be of relevance to a number of problems involving thin films. What distinguishes different films, substrates and film thickness regimes, at least for slow evolution where inertial effects are not significant, is essentially the form of (effective) disjoining pressure that, in addition to liquid/solid interaction, may include the effects of anchoring in the context of liquid crystals; interactions of electric or magnetic type in the context of ferrofluids [29]; or composite substrates in the case of polymer films [18]. The influence of the functional form of such effective disjoining pressure on film stability was discussed in two spatial dimensions (2D) recently [28].…”

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confidence: 99%

Computing dynamics of thin films via large scale GPU-based simulations

Lam

Cummings

Kondic

2019

Journal of Computational Physics: X

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We present the results of large scale simulations of 4th order nonlinear partial differential equations of diffusion type that are typically encountered when modeling dynamics of thin fluid films on substrates. The simulations are based on the alternate direction implicit (ADI) method, with the main part of the computational work carried out in the GPU computing environment. Efficient and accurate computations allow for simulations on large computational domains in three spatial dimensions (3D) and for long computational times. We apply the methods developed to the particular problem of instabilities of thin fluid films of nanoscale thickness. The large scale of the simulations minimizes the effects of boundaries, and also allows for simulating domains of the size encountered in published experiments. As an outcome, we can analyze the development of instabilities with an unprecedented level of detail. A particular focus is on analyzing the manner in which instability develops, in particular regarding differences between spinodal and nucleation types of dewetting for linearly unstable films, as well as instabilities of metastable films. Simulations in 3D allow for consideration of some recent results that were previously obtained in the 2D geometry (J. Fluid Mech. 841, 925 (2018)). Some of the new results include using Fourier transforms as well as topological invariants (Betti numbers) to distinguish the outcomes of spinodal and nucleation types of instabilities, describing in precise terms the complex processes that lead to the formation of satellite drops, as well as distinguishing the shape of the evolving film front in linearly unstable and metastable regimes. We also discuss direct comparison between simulations and available experimental results for nematic liquid crystal and polymer films.

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Stability and Dewetting of Thin Liquid Films

Cited by 28 publications

References 66 publications

Macroscale adhesion of gecko setae reflects nanoscale differences in subsurface composition

Macroscale adhesion of gecko setae reflects nanoscale differences in subsurface composition

Statistical Analysis of Simulations of Coarsening Droplets Coating a Hydrophobic Surface

Computing dynamics of thin films via large scale GPU-based simulations

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