Capillary rupture of suspended polymer concentric rings

TL;DR

This study investigates the capillary rupture behavior of suspended viscous concentric polymer rings, revealing how substrate confinement and ring spacing influence rupture modes and resulting surface patterns.

Contribution

First experimental analysis of simultaneous capillary instability in suspended concentric rings, highlighting the effects of substrate confinement and phase correlation on rupture modes.

Findings

Weak confinement leads to independent or out-of-phase rupture modes.

Strong confinement results in in-phase rupture and radial droplet alignment.

Pattern formation is governed by a competition between phase correlation and wavelength.

Abstract

We present the first experimental study on the simultaneous capillary instability amongst viscous concentric rings suspended atop an immiscible medium. The rings ruptured upon annealing, with three types of phase correlation between neighboring rings. In the case of weak substrate confinement, the rings ruptured independently when they were sparsely distanced, but via an out-of-phase mode when packed closer. If the substrate confinement was strong, the rings would rupture via an in-phase mode, resulting in radially aligned droplets. The concentric ring geometry caused a competition between the phase correlation of neighboring rings and the kinetically favorable wavelength, yielding an intriguing, recursive surface pattern. This frustrated pattern formation behavior was accounted for by a scaling analysis.