Stretching and Compressing Capillary Bridges on Hydrophilic, Hydrophobic, and Liquid-infused Surfaces

TL;DR

This study compares how capillary liquid bridges behave on hydrophilic, hydrophobic, and liquid-infused surfaces, revealing how surface properties influence bridge dynamics, forces, and stability through experiments and simulations.

Contribution

It provides a systematic analysis of capillary bridge behavior across different surface types, highlighting the effects of pinning, hysteresis, and liquid exchange, which was not comprehensively studied before.

Findings

Contact line pinning causes stick-slip motion on glass.

Hysteresis is pronounced on DMS-functionalized surfaces.

LIS surfaces exhibit minimal force variation and enable liquid exchange.

Abstract

Aqueous capillary liquid bridges are ubiquitous in nature and in technological processes. Here, we comparatively investigate capillary bridges formed between three distinct types of surfaces: (i) hydrophilic glass, (ii) hydrophobic dichlorodimethylsilane (DMS)-functionalized glass, and (iii) silicone-oil-infused LIS. We combine experimental measurements and computer simulations of the capillary bridge evolution upon changes in the gap size between the surfaces, deriving in each case the bridge geometry and the resulting capillary force. The results, also compared with predictions from the existing theory, follow expected trends on glass and DMS-functionalized surfaces: contact line pinning dominates the bridge behavior on glass with a characteristic stick-slip motion, whereas a pronounced advancing and receding hysteresis is observed on DMS surfaces. On LIS, the absence of pinning leads to minimal force variation, gravity-driven breaking of the bridge symmetry, and possible liquid exchange between LIS through bridge cloaking. These effects become particularly significant in asymmetric bridge configurations combining LIS and DMS surfaces, where the transfer of lubricant from LIS to DMS modifies the effective surface tension and alters bridge-surface interactions. Our systematic comparison of the capillary bridge behavior across solid and liquid interfaces with varying wettability provides a foundation for designing functional surface applications with controlled bridge-surface interactions.