Film Stratification in the Presence of Colloidal Particles

Sethumadhavan, Gopi; Nikolov, and Alex; Wasan, Darsh T.

doi:10.1021/la000936l

Cited by 37 publications

(26 citation statements)

References 15 publications

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“…To the best of our knowledge, all the published studies 43,44,[48][49][50][53][54][55] have focused exclusively on the expansion of a single isolated domain, far away from the Plateau border. There is a sheer lack of any experimental data on if and how expansion dynamics change when the expanding domain comes in contact with the Plateau border.…”

Section: Introductionmentioning

confidence: 99%

Domain expansion dynamics in stratifying foam films: experiments

2015

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The stability, rheology and applications of foams, emulsions and colloidal sols depend on the hydrodynamics and thermodynamics of thin liquid films that separate bubbles, drops and particles respectively. Thin liquid films containing micelles, colloidal particles, liquid crystals or polyelectrolyte-surfactant mixtures exhibit step-wise thinning or stratification, often attributed to the layer-by-layer removal of the aforementioned supramolecular structures. Stratification proceeds through emergence and growth of thinner circular domains within a thicker film, and the domain expansion dynamics are the focus of this study. Domain and associated thickness variation in foam films made from sodium dodecyl sulfate (SDS) micellar solutions are examined using a Scheludko-type cell with a novel technique we call Interferometry Digital Imaging Optical Microscopy (IDIOM). Below 100 nm, stratification and drainage cause a thickness-dependent variation in reflected light intensity, visualized as progressively darker shades of gray. We show that the domain expansion dynamics exhibit two distinct growth regimes with characteristic scaling laws. Initially, the radius of the isolated domains grows with square root time, and the expansion rate can be characterized by an apparent diffusion constant. In contrast, after a section of the expanding domain coalesces with the Plateau border, the contact line between domain and the surrounding thicker region moves a constant velocity. We show that a similar transition from a constant diffusivity to a constant velocity regime is also realized when a topological instability occurs at the contact line between the growing thinner isolated domain and the surrounding thicker film. Though several studies have focused on the expansion dynamics of isolated domains that exhibit a diffusion-like scaling, the change in expansion kinetics observed after domains contact with the Plateau border has not been reported and analyzed before.

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Section: Introductionmentioning

confidence: 99%

Domain expansion dynamics in stratifying foam films: experiments

2015

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“…Furthermore, it is possible that silica particles could be entrapped in the viscoelastic thin film created by the adsorbed proteins thereof constituting an additional layer that provides additional repulsive forces between droplets [56]. In a separate study, instead of β-lactoglobulin another milk protein sodium caseinate was used in mixtures with silica to show that significant reduction in the interfacial tension between oil-water took place when both species were present in the aqueous phase [45].…”

Section: Effect Of Wpimentioning

confidence: 99%

Pickering particle and emulsifier co-stabilised emulsions produced via rotating membrane emulsification

Arkoumanis

Norton

Spyropoulos

2019

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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Producing stable particle-stabilised emulsions of small droplet sizes and high monodispersity via membrane emulsification approaches is hindered by the poor mixing environment during processing and the low diffusivity and minimal interfacial tension lowering capacity of colloidal particles. The present study investigates the co-stabilisation (particles and emulsifiers) of O/W emulsions formed by rotating membrane emulsification. Formulation aspects of the employed co-stabilisation strategy (type/concentration of emulsifiers and type/size of particles) were assessed at a fixed trans-membrane pressure (10 kPa) and rotational velocity (2000 rpm). Emulsion microstructure was shown to be affected by the occurrence of emulsifier/particle interactions. In formulations where these interactions are synergistic and emulsifier content is low, interfacial stabilisation is carried out by both species and resulting emulsions possess smaller droplet sizes, higher monodispersity indices and enhanced stability against coalescence, compared to systems stabilised by either of the two components alone. This work concludes that a carefully controlled co-stabilisation strategy can overcome the current challenges associated with the production of particle-stabilised emulsions via membrane emulsification methods.

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“…Stratification phenomena have been reported for dispersions of monodisperse silica particles. [67] The effect of added surfactant or proteins changes the film behaviour dramatically.…”

Section: Drainage Of Foam Filmsmentioning

confidence: 99%

Aqueous Foams: A Field of Investigation at the Frontier Between Chemistry and Physics

Langévin¹

2008

ChemPhysChem

106

113

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This paper reviews the properties of aqueous foams. The current state of knowledge is summarized briefly and the interdisciplinary aspects of this field of investigation are emphasized. Many phenomena are controlled by physical laws, but they are highly dependent upon the chemicals used as foam stabilizers: surfactants, polymers, particles. Most of the existing work is related to surfactants and polymer foams, and little is known yet for particle foams although research in this field is becoming popular. This article presents the general concepts used to describe the monolayers and the films and also some of the recent advances being made in this area.

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Film Stratification in the Presence of Colloidal Particles

Cited by 37 publications

References 15 publications

Domain expansion dynamics in stratifying foam films: experiments

Domain expansion dynamics in stratifying foam films: experiments

Pickering particle and emulsifier co-stabilised emulsions produced via rotating membrane emulsification

Aqueous Foams: A Field of Investigation at the Frontier Between Chemistry and Physics

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