Stability of Clay Particle-Coated Microbubbles in Alkanes against Dissolution Induced by Heating

Abstract

We investigated the dissolution and morphological dynamics of air bubbles in alkanes stabilized by fluorinated colloidal clay particles when subjected to temperature changes. A model for bubble dissolution with time-dependent temperature reveals that increasing the temperature enhances the bubble dissolution rate in alkanes, opposite to the behavior in water, due to the differing trends in gas solubility. Experimental results for uncoated air bubbles in decane and hexadecane confirm this prediction. Clay-coated bubbles in decane and hexadecane are shown to be stable in air-saturated oil at constant temperature, where dissolution is driven mainly by the Laplace pressure. When the temperature increases from ambient, the particle-coated bubbles are prone to dissolution as the oil phase becomes under-saturated. The interfacial layer of particles is observed to undergo buckling and crumpling, without shedding of clay particles. Increasing the concentration of particles is shown to enhance the bubble stability by providing a higher resistance to dissolution. When subjected to complex temperature cycles, for which the effect of the time-dependent temperature is dominant, the clay-coated bubbles can resist long-term dissolution in conditions for which uncoated bubbles dissolve completely. These results underpin the design of ultra-stable oil foams stabilized by solid particles with improved shelf life under changing environmental conditions. † These authors contributed equally 2/21

Tuning local microstructure of colloidal gels by ultrasound-activated deformable inclusions

“…Bubble dissolution can in principle be arrested by the bulk yield stress of the surrounding material 26,41 , by the interfacial yield stress of particles adsorbed on the bubble surface 42 , or both 43 . In our system, the yield stress of the colloidal gel is too low to arrest bubble dissolution, as predicted in Section 3.1, and the interfacial particle layer cannot prevent dissolution either, similarly to what has been reported in Newtonian solvents under-saturated with gas 44,45 . r c ) is observed before ultrasound is applied.…”

Collapse mechanisms and extreme deformation of particle-laden interfaces

“…Different regimes were revealed: from soft crumpling for small particles, to faceting and granular arches for large particles [62]. For bubbles dissolving in oil and coated with hydrophobic particles, buckling of the interface was observed [63].…”

Stability of bubbles in wax-based oleofoams: decoupling the effects of bulk oleogel rheology and interfacial rheology

“…Oleofoams that are stable at room temperature may be destabilized by heating both because the crystals can melt (Binks et al 2016), and because of enhanced bubble dissolution due to the changes in gas solubility with temperature. Enhanced bubble dissolution upon changes in temperature has been previously shown to destroy particle-stabilized bubbles in water, where air solubility increases with cooling (Poulichet and Garbin 2015), and in alkanes, where air solubility increases with heating (Achakulwisut et al 2017).…”