Static wetting of a barrel-shaped droplet on a soft-layer-coated fiber

TL;DR

This study investigates how a barrel-shaped droplet deforms a soft-layer-coated fiber, revealing effects of fiber radius, surface tension differences, and soft layer softness on deformation patterns and potential long-range interactions.

Contribution

It provides new insights into the static deformation behavior of droplets on soft-layer-coated fibers, highlighting the influence of fiber radius, surface tension disparities, and layer softness.

Findings

Deformation increases as the fiber radius decreases.

Differences in solid surface tensions cause disparities in deformation.

Pronounced displacement oscillations occur when the layer is soft and fiber radius is small.

Abstract

A droplet can deform a soft substrate due to capillary forces when they are in contact. We study the static deformation of a soft solid layer coated on a rigid cylindrical fiber when an axisymmetric barrel-shaped droplet is embracing it. We find that the elastic deformation increases with decreasing rigid fiber radius. Significant disparities of deformation between the solid-liquid side and the solid-gas side are found when their solid surface tensions are different. When the coated layer is soft enough and the rigid fiber radius is less than the thickness of the coated layer, pronounced displacement oscillations are observed. Such slow decay of deformation with distances from the contact line position suggests a possible long-range interaction between droplets on a soft-layer-coated fiber.