Liquid-bridge stability and breakup on surfaces with contact-angle hysteresis

Abstract

We study the stability and breakup of liquid bridges with a free contact line on surfaces with contact-angle hysteresis (CAH) under zero-gravity conditions. Non-ideal surfaces exhibit CAH because of surface imperfections, by which the constraints on three-phase contact lines are influenced. Given that interfacial instabilities are constraintsensitive, understanding how CAH affects the stability and breakup of liquid bridges is crucial for predicting the drop size in contact-drop dispensing. Unlike ideal surfaces on which contact lines are always free irrespective of surface wettability, contact lines may undergo transitions from pinned to free and vice-versa during drop deposition on non-ideal surfaces. Here, we experimentally and theoretically examine how stability and breakup are affected by CAH, highlighting cases where stability is lost during a transition from a pinned-pinned (more constrained) to pinned-free (less constrained) interface-rather than a critical state. This provides a practical means of expediting or delaying stability loss. We also demonstrate how the dynamic contact angle can control the contact-line radius following stability loss. *

Detachment Force of Particles with Pinning of Contact Line from Fluid Bubbles/Droplets

“…Note that the force abruptly decreases with the transition to the sliding regime, so, in principle, detachment can still occur at the same displacement. This regime is similar to the one described by Akbari and Hill, who studied experimentally and theoretically the stability and breakup of liquid bridges with a free contact line on surfaces with contact-angle hysteresis. Akbari and Hill have identified the regime in which the stability of liquid bridges is lost during a transition from the pinned to free interface.…”

Influence of the Polarity of the Electric Field on Electrorheometry

“…The general idea is that the electric field, when oriented in the opposite direction of gravity, generates Coulombian forces that counterbalance the gravitational force. This conclusion and other results that can be obtained by means of CaBEER with different liquids may have a relevant impact on the study of the stability and dynamics of liquid bridges under the presence of an external electric field, which may open new doors for pioneering works in a broad range of applications, including crystal growth, surface patterning, nano-printing, nano-lithography, aggregation and coalescence of flexible fibers, and capillary induced collapse of elastic structures [15].…”

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“…The involved type of product varies according to geographic region, but the most frequent ones include sodium hypochlorite (present in bleaches and disinfectants) and sodium hydroxide (caustic soda) (23)(24) . The physiopathology of the harm caused by caustic substances involves deep penetration (able to reach the muscularis propria), causing liquefactive necrosis of the mucosa, following damage to the submucosa.…”