Drying of a Solution in a Meniscus: A Model Coupling the Liquid and the Gas Phases

Abstract

A model simulating the drying of a solution in a meniscus in contact with a moving substrate is developed. It takes into account the hydrodynamics in the solution in the framework of the lubrication approximation, the vapor diffusion in the gas phase, and the variation of physical properties during drying. The free surface profile and spatial evaporation flux are not imposed a priori but result from the simulation of the mass transfer in the liquid/gas system (1.5-sided model). Several regimes are observed depending on the substrate velocity. For a large substrate velocity, the classical Landau-Levich regime is obtained. For smaller velocities, a drying front appears that is characterized by a strong concentration gradient and a peak in the evaporation flux. The coupling between the evaporation flux and the meniscus shape in this regime is analyzed. Another regime appears at a very low substrate velocity and seems to be driven by a competition between advection and diffusion. This macroscopic model simulates recent experimental results, namely, the dependence of the deposit thickness on the substrate velocity, which scales as 1/V in the regime dominated by evaporation.

Printing 2D Conjugated Polymer Monolayers and Their Distinct Electronic Properties

“…For 5 mg mL −1 DPP2T‐TT/chloroform solution coated on IL at 25 °C, we have previously determined that the transition from evaporation regime to Landau–Levich regime occurs at ≈10 mm s −1 9. With decrease in solution concentration, the viscosity of the solution decreases, hence we expect the transition speed to increase at lower solution concentration 16. This means that for all conditions used in our study, the film deposition occurs in the evaporation regime.…”

“…[9] With decrease in solution concentration, the viscosity of the solution decreases, hence we expect the transition speed to increase at lower solution concentration. [16] This means that for all conditions used in our study, the film deposition occurs in the evaporation regime. Indeed, we observed decrease in film thickness with increase in printing speed, and when the film thickness reached monolayer, we then observed decrease in film coverage (Θ) with increase in printing speed.…”

Patterned deposition at moving contact lines

“…For the class of evaporation models that assume that evaporation is controlled by diffusion in the gas phase; see, e.g., Ref. [22,97,114] and the discussion below.…”

“…Such evolution equations are employed in a number of studies of drying films of solutions and of deposition processes from contact lines of solutions with volatile solvent. However, only very few studies allow contact lines to move and are therefore, in principle, able to describe the dynamics of a periodic deposition process, i.e., the stick-slip character of the process [5,114,[116][117][118]. Many works focus on evaporating drops with a contact line that always remains pinned at its initial position [115,[119][120][121].…”

Rapid prototyping techniques for the fabrication of biosensors

“…While these are not necessarily considered RP techniques, dip-coating is discussed here to establish the baseline of what is possible and then to contextualize the benefi ts of RP techniques. The uniformity of a dried dip-or spin-coated fi lm is diffi cult to optimize as Marangoni and capillary fl ows redistribute solutes unevenly (Hurd, 1994;Berteloot et al ., 2008;Doumenc and Guerrier, 2010). Bietsch et al .…”