Dewetting of a thin polymer film under shear

TL;DR

This study investigates how shear influences the rupture behavior of ultrathin polymer films, revealing regimes where shear delays, suppresses, or transiently balances rupture, with nonlinear effects being crucial under shear.

Contribution

It introduces a numerical scheme to analyze shear effects on thin film rupture, identifying distinct regimes and emphasizing the importance of nonlinearities under shear.

Findings

Low shear delays rupture

High shear suppresses rupture

Transient regime with balanced forces

Abstract

The objective of this work is to study the role of shear on the rupture of ultrathin polymer films. To do so, a finite-difference numerical scheme for the resolution of the thin film equation was set up taking into account capillary and van der Waals (vdW) forces. This method was validated by comparing the dynamics obtained from an initial harmonic perturbation to established theoretical predictions. With the addition of shear, three regimes have then been evidenced as a function of the shear rate. In the case of low shear rates the rupture is delayed when compared to the no-shear problem, while at higher shear rates it is even suppressed: the perturbed interface goes back to its unperturbed state over time. In between these two limiting regimes, a transient one in which shear and vdW forces balance each other, leading to a non-monotonic temporal evolution of the perturbed interface, has been identified. While a linear analysis is sufficient to describe the rupture time in the absence of shear, the nonlinearities appear to be essential otherwise.