  The dynamic of contact formation between soft materials immersed in a fluid
is accompanied by fluid drainage and elastic deformation. As a result,
controlling the coupling between lubrication pressure and elasticity provides
strategies to design materials with reversible and dynamic adhesion to wet or
flooded surfaces. We characterize the elastic deformation of a soft coating
with nanometer-scale roughness as it approaches and contacts a rigid surface in
a fluid environment. The lubrication pressure during the approach causes
elastic deformation and prevents contact formation. We observe deformation
profiles that are drastically different from those observed for elastic
half-space when the thickness of the soft coating is comparable to the
hydrodynamic radius. In contrast, we show that surface roughness favors fluid
drainage without altering the elastic deformation. As a result, the coupling
between elasticity and slip (caused by surface roughness) can lead to trapped
fluid pockets in the contact region.
