Double Inversion of Emulsions By Using Nanoparticles and a Di‐Chain Surfactant

Binks, Bernard P.; Rodrigues, Jhonny A.

doi:10.1002/anie.200700880

Cited by 144 publications

(147 citation statements)

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“…1 The phenomenon of double phase inversion of emulsions stabilized partially by particles was described by one of us in dodecane− water systems containing anionic Ludox HS-30 nanoparticles and cationic surfactant. 11 At a fixed particle concentration, increasing the concentration of dichain surfactant resulted in emulsions inverting from o/w to w/o initially and then back to o/w at high enough concentration. Using complementary experiments, these findings were discussed in terms of the adsorption of surfactant to particle surfaces and the influence this had on the wettability of the particles at the oil−water interface.…”

Section: ■ Introductionmentioning

confidence: 98%

Direct Measurement of Contact Angles of Silica Particles in Relation to Double Inversion of Pickering Emulsions

2013

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In an alkane-water system containing submicrometer silica particles at high pH, double emulsion inversion from oil-in-water (o/w) to water-in-oil (w/o) to oil-in-water can be effected by increasing the concentration of a dichain cationic surfactant in water. The contact angle θ of the particles at the planar oil-water interface has been measured directly using freeze-fracture shadow-casting cryo-scanning electron microscopy, enabling single-particle measurements of high accuracy. θ passes through a maximum with respect to surfactant concentration. It is shown that particles undergo a hydrophilic-hydrophobic-hydrophilic transition corresponding closely to the o/w-w/o-o/w transformation observed in emulsions. These results unequivocally link the single-particle contact angles to the type of particle-stabilized emulsion, confirming macroscopic emulsion inversion on the microscopic level.

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Section: ■ Introductionmentioning

confidence: 98%

Direct Measurement of Contact Angles of Silica Particles in Relation to Double Inversion of Pickering Emulsions

2013

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“…Theoretical models of emulsion morphology and phase inversion 7 Bancroft's rule 9 Hydrophile-lipophilie balance (HLB) 10 Phase inversion temperature (PIT) 11 Winsor R-ratio 12 Hydophilic-liphophilic deviation (HLD) 13 Techniques to Monitor Transitional phase inversion emulsification 19 Transitional phase inversion via phase inversion temperature (PIT) method 19 Transitional phase inversion emulsification via competitive adsorption of surfactants 21 Transitional phase inversion of polymer-stabilized emulsions 22 Light-triggered transitional phase inversion 23 Phase Inversion of Particle-Stabilized Emulsions 24 Effect of particle wettability on phase inversion of Pickering emulsions 25 Varying particle wettability by surfactant adsorption 25 Effect of suspension composition and concentration on phase inversion 27 Phase inversion using stimuli-responsive particles 28 Phase inversion of Pickering air-water emulsions 29 Phase inversion of shape-changing amphiphilic particle-stabilized emulsions 30 Flow-Induced Phase Inversion 31 Phase inversion using static mixers 32 Thixotropy-induced phase inversion 34 Phase inversion in microfluidic devices 35 Phase inversion using membrane emulsification 36 Summary & Outlook PIE has predominantly been classified into two categories-transitional and catastrophic.…”

Section: Introductionmentioning

confidence: 99%

Recent Developments in Phase Inversion Emulsification

Kumar

Cheng

et al. 2015

Ind. Eng. Chem. Res.

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Emulsions are multiphasic fluid systems in which liquid droplets are dispersed in another immiscible liquid. The main components of an emulsion are the two liquid phases, typically oil and water, and the emulsifier, which stabilizes the interface between the two liquid phases. Emulsifiers can be a variety of molecules, such as polymers, amphiphilic surfactants, and proteins, and they can also be colloidal particles. Emulsion phase inversion is the process of interconversion between two types of simple emulsions: water-in-oil and oil-in-water emulsions. Phase inversion can be induced by shifting the emulsifier affinity from one phase to the other, which is called transitional phase inversion. It can also be triggered by a change in the water-to-oil ratio of the emulsion, which leads to a process known as catastrophic phase inversion. With recent advances in the stabilization of emulsions using colloidal particles and stimuli-responsive surfactants, numerous novel emulsion systems that undergo emulsion phase inversion by means of various mechanisms have been developed. In this review, we highlight the most recent developments in the field of emulsion phase inversion, focusing on transitional phase inversion, inversion of particle-stabilized emulsions, and flowand shear-induced phase inversion. We also discuss and compare state-of-the-art analytical methods that have been used to detect and understand the emulsion phase inversion process. Our coverage spans from the early concepts of Bancroft's rule through the concept of semiquantitative hydrophilic−lipophilic balance to the more recent theoretical models used to predict and control phase inversion phenomena. We conclude this review by presenting an outlook on the future directions and outstanding problems that warrant future investigations to fully understand the mechanism of emulsion phase inversion at the single-droplet level.

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“…Typically surfactant molecules are mixed with nanoparticles in emulsions to enhance particle attachment [21][22][23]. Surfactant adsorption onto the particle surfaces alters the interactions between drops and nanoparticles.…”

Section: Introductionmentioning

confidence: 99%