Numerical analysis of Pickering emulsion stability: insights from ABMD simulations

Sicard, François; Striolo, Alberto

doi:10.1039/c6fd00055j

Cited by 19 publications

(43 citation statements)

References 47 publications

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“…A number of spherical NPs were placed randomly at the water-decane interface with their polar (nonpolar) part in the water (oil) phase to reach the desired water-decane interfacial area per NP. Following previous work [24,34], the NPs considered in this study are spherical and of two different types: Janus and homogeneous. The emulsion systems are stabilized by a sufficiently dense layer of NPs [24].…”

Section: System Characterisation: Droplets and Nanoparticlesmentioning

confidence: 99%

“…Following previous work [24,34], the NPs considered in this study are spherical and of two different types: Janus and homogeneous. The emulsion systems are stabilized by a sufficiently dense layer of NPs [24]. We considered water droplets coated with 160 spherical Janus and homogeneous nanoparticles of type 55JP and 75HP , respectively.…”

Section: System Characterisation: Droplets and Nanoparticlesmentioning

confidence: 99%

“…We study the shape and buckling transitions of model water droplets coated with spherical nanoparticles and immersed in an organic solvent. The procedure and the parametrisation details are fully described in prior work [22][23][24] and in the Supporting Information (SI). The particles are of two different types: Janus and homogeneous.…”

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confidence: 99%

“…We discriminate the two mechanisms with the evolution of their respective nanoparticle threephase contact angle distributions. While for Janus particles the distribution remains unimodal, albeit skewed when the droplet is significantly shrinked, for homogeneous particles, the evolution of the contact angle distribution becomes bimodal with some particles becoming more/less immersed in the aqueous phase.We consider a system initially made by a spherical water droplet immersed in oil, and stabilized by a sufficiently dense layer of NPs [24]. The initial shape of the droplet is spherical.…”

mentioning

confidence: 99%

“…We consider a system initially made by a spherical water droplet immersed in oil, and stabilized by a sufficiently dense layer of NPs [24]. The initial shape of the droplet is spherical.…”

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confidence: 99%

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Buckling in armored droplets

Sicard

Striolo

2017

Nanoscale

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The issue of the buckling mechanism in droplets stabilized by solid particles (armored droplets) is tackled at a mesoscopic level using dissipative particle dynamics simulations. We consider spherical water droplet in a decane solvent coated with nanoparticle monolayers of two different types: Janus and homogeneous. The chosen particles yield comparable initial three-phase contact angles, chosen to maximize the adsorption energy at the interface. We study the interplay between the evolution of droplet shape, layering of the particles, and their distribution at the interface when the volume of the droplets is reduced. We show that Janus particles affect strongly the shape of the droplet with the formation of a crater-like depression. This evolution is actively controlled by a close-packed particle monolayer at the curved interface. On the contrary, homogeneous particles follow passively the volume reduction of the droplet, whose shape does not deviate too much from spherical, even when a nanoparticle monolayer/bilayer transition is detected at the interface. We discuss how these buckled armored droplets might be of relevance in various applications including potential drug delivery systems and biomimetic design of functional surfaces.Keywords: Pickering emulsions, DPD simulations, Janus/homogeneous nanoparticles, bucklingPickering emulsions [1], i.e. particle-stabilized emulsions, have been studied intensively in recent years owning to their wide range of applications including biofuel processing [2] and food preservation [3,4]. They have also been developed as precursors to magnetic particles for imaging [5] and drug delivery systems [6]. Even with their widespread use, they remain, however, underutilized. In Pickering emulsions, particles and/or nanoparticles (NPs) with suitable surface chemistries adsorb at the droplet surfaces, with an adsorption energy of up to thousands of times the thermal energy. The characteristics of Pickering emulsions pose a number of intriguing fundamental physical questions including a thorough understanding of the perennial lack of detail about how particles arrange at the liquid/liquid interface. Other not completely answered questions include particle effects on interfacial tension [7], layering [8], buckling [9-11] and particle release [8,12].In some important processes that involve emulsions, it can be required to reduce the volume of the dispersed droplets [9,[13][14][15]. The interface may undergo large deformations that produce compressive stresses, causing localized mechanical instabilities. The proliferation of these localized instabilities may then result in a variety of collapse mechanisms [8,10,11]. Despite the vast interest in particle-laden interfaces, the key factors that determine the collapse of curved particle-laden interfaces are still subject of debate. Indeed, although linear elasticity describes successfully the morphology of buckled particle-laden droplets, it is still unclear whether the onset of buckling can be explained in terms of classic elastic buckling...

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Section: System Characterisation: Droplets and Nanoparticlesmentioning

confidence: 99%

Section: System Characterisation: Droplets and Nanoparticlesmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

“…We consider a system initially made by a spherical water droplet immersed in oil, and stabilized by a sufficiently dense layer of NPs [24]. The initial shape of the droplet is spherical.…”

mentioning

confidence: 99%

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Buckling in armored droplets

Sicard

Striolo

2017

Nanoscale

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Multiphase Microreactors Based on Liquid–Liquid and Gas–Liquid Dispersions Stabilized by Colloidal Catalytic Particles

Dedovets

Leclercq

et al. 2021

Angewandte Chemie

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Pickering emulsions, foams, bubbles, and marbles are dispersions of two immiscible liquids or of a liquid and a gas stabilized by surface‐active colloidal particles. These systems can be used for engineering liquid–liquid–solid and gas–liquid–solid microreactors for multiphase reactions. They constitute original platforms for reengineering multiphase reactors towards a higher degree of sustainability. This Review provides a systematic overview on the recent progress of liquid–liquid and gas–liquid dispersions stabilized by solid particles as microreactors for engineering eco‐efficient reactions, with emphasis on biobased reagents. Physicochemical driving parameters, challenges, and strategies to (de)stabilize dispersions for product recovery/catalyst recycling are discussed. Advanced concepts such as cascade and continuous flow reactions, compartmentalization of incompatible reagents, and multiscale computational methods for accelerating particle discovery are also addressed.

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