Pickering emulsions stabilized by coloured organic pigment particles

Binks, Bernard P.; Olusanya, Samuel O.

doi:10.1039/c6sc03085h

Cited by 38 publications

(26 citation statements)

References 60 publications

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“…18 The emulsion type is primarily determined by the particle wettability at the oil-water interface, although the relative volume fraction of the oil phase can also play a role. 11,[19][20][21] In recent years, there has been growing interest in Pickering nanoemulsions, which comprise droplets of less than approximately 200 nm in diameter. [22][23][24][25][26][27][28][29][30] In contrast to conventional macroemulsions, nanoemulsions are much less prone to gravitational creaming or sedimentation.…”

Section: Commonmentioning

confidence: 99%

How Do Charged End-Groups on the Steric Stabilizer Block Influence the Formation and Long-Term Stability of Pickering Nanoemulsions Prepared Using Sterically Stabilized Diblock Copolymer Nanoparticles?

et al. 2020

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Reversible addition−fragmentation chain transfer (RAFT) solution polymerization is used to prepare well-defined poly(glycerol monomethacrylate) (PGMA) chains bearing carboxylic acid, tertiary amine, or neutral end-groups. Each of these PGMA precursors was then chain-extended in turn via RAFT aqueous emulsion polymerization of 2,2,2-trifluoroethyl methacrylate to form spherical nanoparticles as confirmed by transmission electron microscopy (TEM) analysis. Dynamic light scattering studies indicated an intensity-average diameter of approximately 25 nm. Aqueous electrophoresis measurements confirmed that the amine-functional nanoparticles became cationic at low pH owing to end-group protonation. In contrast, carboxylic acid-functional nanoparticles became appreciably anionic at pH 10 owing to end-group ionization. Finally, nanoparticles bearing neutral end-groups exhibited zeta potentials close to zero over a range of solution pH. High-shear homogenization of n-dodecane in the presence of such sterically stabilized nanoparticles led to the formation of oil-in-water Pickering macroemulsions with volume-average diameters of 20− 30 μm. High-pressure microfluidization was then used to prepare the three corresponding Pickering nanoemulsions. Each Pickering nanoemulsion was characterized by analytical centrifugation and TEM studies of the dried nanoemulsion droplets confirmed their original nanoparticle superstructure. The nanoparticle adsorption efficiency at the oil−water interface was assessed by gel permeation chromatography (using a UV detector) for each nanoparticle type at both pH 3 and 7. Nanoparticles with charged end-groups exhibited relatively low adsorption efficiency, whereas up to 90% of the neutral nanoparticles were adsorbed onto the oil droplets. This observation was supported by small-angle X-ray scattering experiments, which indicated that the packing efficiency of neutral nanoparticles around oil droplets was higher than that of nanoparticles bearing charged end-groups. Analytical centrifugation was used to evaluate the colloidal stability of the aged Pickering nanoemulsions. Pickering nanoemulsions stabilized with nanoparticles bearing charged end-groups proved to be significantly less stable than those prepared using neutral end-groups.

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Section: Commonmentioning

confidence: 99%

How Do Charged End-Groups on the Steric Stabilizer Block Influence the Formation and Long-Term Stability of Pickering Nanoemulsions Prepared Using Sterically Stabilized Diblock Copolymer Nanoparticles?

et al. 2020

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“…S10A, † successful emulsification was only achieved at extremely high concentrations of SiO 2 particles. In fact, at concentrations lower than 11.2% wt complete destabilization was observed within minutes, as evidenced by the amount of oil resolved (fast creaming of emulsions releases a fraction of pure oil) 34 which is 100% (Fig. S10B † ).…”

Section: Resultsmentioning

confidence: 98%

Thinking outside the box: placing hydrophilic particles in an oil phase for the formation and stabilization of Pickering emulsions

Marina

et al. 2018

Chem. Sci.

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“…Recently, using the powdered particle method, we have shown the possibility of forming both w/o and o/w emulsions using coloured organic pigment particles as sole emulsifier and we observed that the colour of the emulsions was similar to that of the pigment used. 51 We presented evidence for the link between the tendency of an emulsion to phase invert catastrophically and the surface energy of the pigment for a range of seven pigments. In this work, we show that both stable water-in-heptane and heptane-in-water emulsions can be produced using a mixture of coloured organic pigment particles of different hydrophobicity.…”

Section: Introductionmentioning

confidence: 99%

Phase Inversion of Colored Pickering Emulsions Stabilized by Organic Pigment Particle Mixtures

Binks

Olusanya

2018

Langmuir

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Pickering emulsions stabilized by a mixture of colored organic pigment particles of different hydrophobicity have been investigated at equal oil/water ratio and a fixed overall particle concentration by several complementary methods. Transitional phase inversion of emulsions from water-in-oil to oil-in-water can be effected by increasing the fraction of hydrophilic pigment orange in mixtures with either hydrophobic pigment yellow, red, indigo, or blue. In two mixtures, we find that a distinct change in the color of emulsions occurs at phase inversion. Although the fraction of pigment orange required depends on the particular hydrophobic pigment selected, phase inversion occurs at a similar surface energy of the particle mixture, which lies between that of the hydrophilic pigment and those of the hydrophobic pigments. We show that both pigment types are present at the oil-water interface simultaneously, giving rise to emulsions that are extremely stable to coalescence. The average drop size for both emulsion types increases toward phase inversion, in line with an increase in the extent of sedimentation/creaming at long times.

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Pickering emulsions stabilized by coloured organic pigment particles

Abstract: Pickering emulsions stabilised by coloured organic pigment particles.

Cited by 38 publications

References 60 publications

How Do Charged End-Groups on the Steric Stabilizer Block Influence the Formation and Long-Term Stability of Pickering Nanoemulsions Prepared Using Sterically Stabilized Diblock Copolymer Nanoparticles?

How Do Charged End-Groups on the Steric Stabilizer Block Influence the Formation and Long-Term Stability of Pickering Nanoemulsions Prepared Using Sterically Stabilized Diblock Copolymer Nanoparticles?

Thinking outside the box: placing hydrophilic particles in an oil phase for the formation and stabilization of Pickering emulsions

Phase Inversion of Colored Pickering Emulsions Stabilized by Organic Pigment Particle Mixtures

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