posted on 2021-11-30, 18:06authored byDavid Feldmann, Bat-El Pinchasik
The
nature of adhesion of droplets to surfaces is a long pending
scientific question. With the evolution of complex surfaces, quantification
and prediction of these adhesion forces become intricate. Nevertheless,
understanding these forces is highly relevant for explaining liquid
transport in nature and establishing design guidelines for manmade
interfaces. Here, it is shown that adhesion of droplets is highly
sensitive to the direction of chemical heterogeneities, both in the
static and dynamic regimes. This dependency is quantified by bending
beam and droplet roll-off experiments. The shape of the fluid contact
line on the microscale elucidates the origin of the direction-dependent
adhesion. Namely, the droplet receding part pins to a higher number
of patches when moving toward to the apex in comparison to the opposite
direction. These findings improve the understanding of droplet adhesion
to surfaces with chemical heterogeneities and directional transport
phenomena.