Modeling of the Drying Process of Liquid Droplet to Form Thin Film

Ozawa, K.; Nishitani, Eisuke; Doi, Masao

doi:10.1143/jjap.44.4229

Cited by 78 publications

(93 citation statements)

References 14 publications

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“…This led to the vitrification of a PS-112K ring before the solution front jumped to next position where it was arrested again. 21 The average jumping distance (i.e., the center-to-center distance between adjacent rings), λ C-C , and the average height of the ring, h, are 30.2 µm and 228 nm, respectively, as determined by AFM (Figure 3b). Locally, the rings appeared as parallel stripes, and the shape of each ring was, however, nonuniform.…”

Section: Methodsmentioning

confidence: 96%

Mesoscale Patterns Formed by Evaporation of a Polymer Solution in the Proximity of a Sphere on a Smooth Substrate: Molecular Weight and Curvature Effects

et al. 2007

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A drop of polymer solution was constrained in a sphere-on-flat geometry, resulting in a liquid capillary bridge. As solvent evaporated, intriguing surface patterns of polymer formed, which were strongly dependent on the molecular weight (MW) of polymer. Dotted arrays were formed at low MW; concentric rings were produced at intermediate MW; concentric rings, rings with fingers, and punch-hole-like structures, however, were yielded at high MW. Rings with fingers as well as punch-hole-like structures were manifestations of simultaneous occurrence of the "stick-slip" motion of the contact line and the fingering instabilities of rings. In addition, the curvature of the sphere in the sphere-on-flat geometry was found to affect the pattern formation. A decrease in the curvature of the sphere led to an earlier onset of the formation of punch-hole-like structures when high-MW polymer was employed as the nonvolatile solute.

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Section: Methodsmentioning

confidence: 96%

Mesoscale Patterns Formed by Evaporation of a Polymer Solution in the Proximity of a Sphere on a Smooth Substrate: Molecular Weight and Curvature Effects

et al. 2007

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“…Recently, various authors have demonstrated an understanding of drying processes based on the evaporation parameters of inks, causing various surface topographies of printed films to manifest themselves [3]- [5]. To solve some of the observed effects, Tekin et.…”

Section: B Motivationmentioning

confidence: 99%

Hydrostatic Optimization of Inkjet-Printed Films

2010

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In this work, we study the optimization of the geometry of inkjet-printed polymer films and develop a simple analytic framework to understand our results and establish limitations on inkjet-printed patterns. We show how drop spacing and ink concentration affect the thickness of a printed film and how hydrostatic conditions with contact angle hysteresis have to be considered to print optimized rectangular features. If advancing and receding contact angle are not taken into account, printed features will either bulge or break up into smaller beads. Thus, we provide a comprehensive analysis of the limits of film formation using regular assemblies of droplets.

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“…The other issue pertaining to evaporating droplets is the phase transition, which may play an essential role in controlling the droplet motion on solid substrates. Typically, an empirical relation is assumed and is used for the evaporation or condensation rate at the droplet surface in literature [25][26][27]. The above two issues concern the theoretical and numerical studies of evaporating droplets.…”

Section: Introductionmentioning

confidence: 99%

Droplet motion in one-component fluids on solid substrates with wettability gradients

Qian

2012

Phys. Rev. E

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CitationDroplet motion in one-component fluids on solid substrates with wettability gradients 2012, 85 (5) Physical Review E Droplet motion on solid substrates has been widely studied not only because of its importance in fundamental research but also because of its promising potentials in droplet-based devices developed for various applications in chemistry, biology, and industry. In this paper, we investigate the motion of an evaporating droplet in onecomponent fluids on a solid substrate with a wettability gradient. As is well known, there are two major difficulties in the continuum description of fluid flows and heat fluxes near the contact line of droplets on solid substrates, namely, the hydrodynamic (stress) singularity and thermal singularity. To model the droplet motion, we use the dynamic van der Waals theory [Phys. Rev. E 75, 036304 (2007)] for the hydrodynamic equations in the bulk region, supplemented with the boundary conditions at the fluid-solid interface. In this continuum hydrodynamic model, various physical processes involved in the droplet motion can be taken into account simultaneously, e.g., phase transitions (evaporation or condensation), capillary flows, fluid velocity slip, and substrate cooling or heating. Due to the use of the phase field method (diffuse interface method), the hydrodynamic and thermal singularities are resolved automatically. Furthermore, in the dynamic van der Waals theory, the evaporation or condensation rate at the liquid-gas interface is an outcome of the calculation rather than a prerequisite as in most of the other models proposed for evaporating droplets. Numerical results show that the droplet migrates in the direction of increasing wettability on the solid substrates. The migration velocity of the droplet is found to be proportional to the wettability gradients as predicted by Brochard [Langmuir 5, 432 (1989)]. The proportionality coefficient is found to be linearly dependent on the ratio of slip length to initial droplet radius. These results indicate that the steady migration of the droplets results from the balance between the (conservative) driving force due to the wettability gradient and the (dissipative) viscous drag force. In addition, we study the motion of droplets on cooled or heated solid substrates with wettability gradients. The fast temperature variations from the solid to the fluid can be accurately described in the present approach. It is observed that accompanying the droplet migration, the contact lines move through phase transition and boundary velocity slip with their relative contributions mostly determined by the slip length. The results presented in this paper may lead to a more complete understanding of the droplet motion driven by wettability gradients with a detailed picture of the fluid flows and phase transitions in the vicinity of the moving contact line.

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Modeling of the Drying Process of Liquid Droplet to Form Thin Film

Cited by 78 publications

References 14 publications

Mesoscale Patterns Formed by Evaporation of a Polymer Solution in the Proximity of a Sphere on a Smooth Substrate: Molecular Weight and Curvature Effects

Mesoscale Patterns Formed by Evaporation of a Polymer Solution in the Proximity of a Sphere on a Smooth Substrate: Molecular Weight and Curvature Effects

Hydrostatic Optimization of Inkjet-Printed Films

Droplet motion in one-component fluids on solid substrates with wettability gradients

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