posted on 2024-02-29, 20:13authored byGabriel Catalini, Nicolás
A. García, Daniel A. Vega, Arash Nikoubashman
We
report molecular dynamics simulation results for the equilibrium
properties of polymer thin films adsorbed onto flat and curved substrates.
We first systematically determined the contact angle of polymer droplets
on flat substrates as a function of the substrate–monomer adsorption
strength and degree of polymerization. Focusing on the fully wetted
regime, we then investigate the effect of the substrate’s topography
on the polymer film configuration by using substrates with varying
local curvature. We find that polymer chains close to the substrate
are significantly stretched (compressed) in regions of high negative
(positive) curvature. Further, we find partial dewetting near regions
of high curvature for thin polymer films. For thicker films, the polymers
fully cover the substrate, and the shape of the liquid–vapor
interface largely follows the shape of the substrate. As the film
thickness is increased further, the liquid–vapor interface
becomes completely flat. These simulation results are corroborated
by analytical calculations using a simplified continuum model that
treats the adsorbed polymers as an incompressible medium. Our findings
show how the substrate topography influences the conformation of individual
chains as well as the shape of the entire film.