Instabilities of layers of deposited molecules on chemically stripe patterned substrates: Ridges vs. drops

Abstract

A mesoscopic continuum model is employed to analyse the transport mechanisms and structure formation during the redistribution stage of deposition experiments where organic molecules are deposited on a solid substrate with periodic stripe-like wettability patterns. Transversally invariant ridges located on the more wettable stripes are identified as very important transient states and their linear stability is analysed. It is found that there exist two different instability modes that result (i) at large ridge volume in the formation of bulges that spill from the more wettable stripes onto the less wettable bare substrate and (ii) at small ridge volume in the formation of small droplets located on the more wettable stripes. These predictions are confirmed by direct numerical simulations of the fully nonlinear evolution equation for two-dimensional substrates. In addition, the influence of different transport mechanisms during redistribution is investigated focusing on the cases of convective transport with no-slip at the substrate, transport via diffusion in the film bulk and via diffusion at the film surface. In particular, it is shown that the transport process does neither influence the linear stability thresholds nor the sequence of morphologies observed in the time simulation, but only the ratio of the time scales of the different process phases.

References in corpus (5)

• Dynamical density functional theory for interacting Brownian particles: stochastic or deterministic?
• Colloquium: Cluster growth on surfaces - densities, size distributions and morphologies
• Thin film evolution equations from (evaporating) dewetting liquid layers to epitaxial growth
• Liquid drops on a surface: using density functional theory to calculate the binding potential and drop profiles and comparing with results from mesoscopic modelling
• Stability of liquid ridges on chemical micro- and nanostripes

Cited by in corpus (12)

• Classical dynamical density functional theory: from fundamentals to applications
• Gradient dynamics models for liquid films with soluble surfactant
• Recent advances in and future challenges for mesoscopic hydrodynamic modelling of complex wetting
• Influence of the fluid structure on the binding potential: comparing liquid drop profiles from density functional theory with results from mesoscopic theory
• Films, layers and droplets: The effect of near-wall fluid structure on spreading dynamics
• Dynamical density functional theory for the evaporation of droplets of nanoparticle suspension
• Comparing kinetic Monte Carlo and Thin-Film Modeling of Transversal Instabilities of Ridges on Patterned Substrates
• Two-dimensional patterns in dip coating -- first steps on the continuation path
• Using evaporation to control capillary instabilities in micro-systems
• Self-assembly of a drop pattern from a two-dimensional grid of nanometric metallic filaments
• Patterns formed in a thin film with spatially homogeneous and non-homogeneous Derjaguin disjoining pressure
• Steady-states of thin film droplets on chemically heterogeneous substrates