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Contact Line Dynamics during the Evaporation of Extended Colloidal Thin Films: Influence of Liquid Polarity and Particle Size
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posted on 2016-11-01, 00:00 authored by Udita
Uday Ghosh, Monojit Chakraborty, Soham De, Suman Chakraborty, Sunando DasGuptaExercising control
over the evaporation of colloidal suspensions
is pivotal to modulate the coating characteristics for specific uses,
wherein the interactions among the liquid, the particles, and the
substrate control the process. In the present study, the contact line
dynamics of a receding colloidal liquid film consisting of particles
of distinctly different sizes (nominal diameters 0.055 and 1 μm
and surface unmodified) during evaporation is analyzed. The role of
the liquid polarity is also investigated by replacing the polar liquid
(water) with a relatively nonpolar liquid (isopropyl alcohol) in the
colloidal suspension. The characteristics of the evaporating receding
meniscus, namely, the film thickness and the curvature are experimentally
evaluated using an image-analyzing interferometry technique. The experimental
results are assessed in conjunction with the augmented Young–Laplace
equation, highlighting the roles of the relevant components of the
disjoining pressure and the polarity of the liquid involved in the
colloidal suspension.