非表示:
キーワード:
Capillary interactions, Elastic forces, Free-surface flows, Interfacial flows, Lubrication, Nanoscale flows, Surface & interfacial phenomena, Aromic force microscopy, Navier-Stokes equation
要旨:
A thin liquid film with nonzero curvature at its free surface spontaneously flows to reach
a flat configuration, a process driven by Laplace pressure gradients and resisted by the
liquid’s viscosity. Inspired by recent progresses on the dynamics of liquid droplets on soft
substrates, we here study the relaxation of a viscous film supported by an elastic foundation.
Experiments involve thin polymer films on elastomeric substrates, where the dynamics of
the liquid-air interface is monitored using atomic force microscopy. A theoretical model
that describes the coupled evolution of the solid-liquid and the liquid-air interfaces is also
provided. In this soft-levelling configuration, Laplace pressure gradients not only drive
the flow, but they also induce elastic deformations on the substrate that affect the flow
and the shape of the liquid-air interface itself. This process represents an original example
of elastocapillarity that is not mediated by the presence of a contact line. We discuss
the impact of the elastic contribution on the levelling dynamics and show the departure
from the classical self-similarities and power laws observed for capillary levelling on rigid
substrates.
