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Dekker RI, Velandia SF, Kibbelaar HVM, Morcy A, Sadtler V, Roques-Carmes T, Groenewold J, Kegel WK, Velikov KP, Bonn D. Is there a difference between surfactant-stabilised and Pickering emulsions? Soft Matter 2023; 19:1941-1951. [PMID: 36808176 DOI: 10.1039/d2sm01375d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
What measurable physical properties allow one to distinguish surfactant-stabilised from Pickering emulsions? Whereas surfactants influence oil/water interfaces by lowering the oil/water interfacial tension, particles are assumed to have little effect on the interfacial tension. Here we perform interfacial tension (IFT) measurements on three different systems: (1) soybean oil and water with ethyl cellulose nanoparticles (ECNPs), (2) silicone oil and water with the globular protein bovine serum albumin (BSA), and (3) sodium dodecyl sulfate (SDS) solutions and air. The first two systems contain particles, while the third system contains surfactant molecules. We observe a significant decrease in interfacial tension with increasing particle/molecule concentration in all three systems. We analyse the surface tension data using the Gibbs adsorption isotherm and the Langmuir equation of state for the surface, resulting in surprisingly high adsorption densities for the particle-based systems. These seem to behave very much like the surfactant system: the decrease in tension is due to the presence of many particles at the interface, each with an adsorption energy of a few kBT. Dynamic interfacial tension measurements show that the systems are in equilibrium, and that the characteristic time scale for adsorption is much longer for particle-based systems than for surfactants, in line with their size difference. In addition, the particle-based emulsion is shown to be less stable against coalescence than the surfactant-stabilised emulsion. This leaves us with the conclusion that we are not able to make a clear distinction between the surfactant-stabilised and Pickering emulsions.
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Affiliation(s)
- Riande I Dekker
- van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
- Van't Hoff Laboratory of Physical and Colloid Chemistry, Debye Institute for Nanomaterials Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Santiago F Velandia
- van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
- Laboratoire Réactions et Génie des Procédés, UMR 7274 CNRS, Université de Lorraine, 1 rue Grandville, 54001 Nancy, France
| | - Heleen V M Kibbelaar
- van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
| | - Azeza Morcy
- van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
| | - Véronique Sadtler
- Laboratoire Réactions et Génie des Procédés, UMR 7274 CNRS, Université de Lorraine, 1 rue Grandville, 54001 Nancy, France
| | - Thibault Roques-Carmes
- Laboratoire Réactions et Génie des Procédés, UMR 7274 CNRS, Université de Lorraine, 1 rue Grandville, 54001 Nancy, France
| | - Jan Groenewold
- Van't Hoff Laboratory of Physical and Colloid Chemistry, Debye Institute for Nanomaterials Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Willem K Kegel
- Van't Hoff Laboratory of Physical and Colloid Chemistry, Debye Institute for Nanomaterials Science, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Krassimir P Velikov
- van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
- Unilever Innovation Centre Wageningen, Bronland 14, 6708 WH Wageningen, The Netherlands
| | - Daniel Bonn
- van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
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Dekker RI, Deblais A, Velikov KP, Veenstra P, Colin A, Kellay H, Kegel WK, Bonn D. Emulsion Destabilization by Squeeze Flow. Langmuir 2020; 36:7795-7800. [PMID: 32543206 PMCID: PMC7366505 DOI: 10.1021/acs.langmuir.0c00759] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 06/15/2020] [Indexed: 06/11/2023]
Abstract
There is a large debate on the destabilization mechanism of emulsions. We present a simple technique using mechanical compression to destabilize oil-in-water emulsions. Upon compression of the emulsion, the continuous aqueous phase is squeezed out, while the dispersed oil phase progressively deforms from circular to honeycomb-like shapes. The films that separate the oil droplets are observed to thin and break at a critical oil/water ratio, leading to coalescence events. Electrostatic interactions and local droplet rearrangements do not determine film rupture. Instead, the destabilization occurs like an avalanche propagating through the system, starting at areas where the film thickness is smallest.
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Affiliation(s)
- Riande I. Dekker
- Van
der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
- Van’t
Hoff Laboratory of Physical and Colloid Chemistry, Debye Institute
for Nanomaterials Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Antoine Deblais
- Van
der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
- Unilever
Innovation Center Wageningen, Bronland 14, 6708 WH Wageningen, The Netherlands
| | - Krassimir P. Velikov
- Van
der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
- Unilever
Innovation Center Wageningen, Bronland 14, 6708 WH Wageningen, The Netherlands
- Soft
Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University, Princetonplein 5, 3584 CC Utrecht, The Netherlands
| | - Peter Veenstra
- Shell
Global Solutions International B.V., Grasweg 31, 1031 HW Amsterdam, The Netherlands
| | - Annie Colin
- Chimie Biologie
Innovation, ESPCI Paris, CNRS, PSL University, 10 rue Vauquelin, 75005 Paris, France
- Centre
de Recherche Paul Pascal, CNRS, Université de Bordeaux, 115 Avenue Schweitzer, 33600 Pessac, France
| | - Hamid Kellay
- Laboratoire
Ondes et Matière d’Aquitaine, UMR 5798, CNRS, Université
de Bordeaux, 351 Cours
de la Libération, 33405 Talence, France
| | - Willem K. Kegel
- Van’t
Hoff Laboratory of Physical and Colloid Chemistry, Debye Institute
for Nanomaterials Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Daniel Bonn
- Van
der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
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Niu R, Heidt S, Sreij R, Dekker RI, Hofmann M, Palberg T. Formation of a transient amorphous solid in low density aqueous charged sphere suspensions. Sci Rep 2017; 7:17044. [PMID: 29213089 PMCID: PMC5719089 DOI: 10.1038/s41598-017-17106-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 11/22/2017] [Indexed: 11/09/2022] Open
Abstract
Colloidal glasses formed from hard spheres, nearly hard spheres, ellipsoids and platelets or their attractive variants, have been studied in great detail. Complementing and constraining theoretical approaches and simulations, the many different types of model systems have significantly advanced our understanding of the glass transition in general. Despite their early prediction, however, no experimental charged sphere glasses have been found at low density, where the competing process of crystallization prevails. We here report the formation of a transient amorphous solid formed from charged polymer spheres suspended in thoroughly deionized water at volume fractions of 0.0002-0.01. From optical experiments, we observe the presence of short-range order and an enhanced shear rigidity as compared to the stable polycrystalline solid of body centred cubic structure. On a density dependent time scale of hours to days, the amorphous solid transforms into this stable structure. We further present preliminary dynamic light scattering data showing the evolution of a second slow relaxation process possibly pointing to a dynamic heterogeneity known from other colloidal glasses and gels. We compare our findings to the predicted phase behaviour of charged sphere suspensions and discuss possible mechanisms for the formation of this peculiar type of colloidal glass.
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Affiliation(s)
- Ran Niu
- Institute of Physics, Johannes Gutenberg University, D-55099, Mainz, Germany.
| | - Sabrina Heidt
- Institute of Physics, Johannes Gutenberg University, D-55099, Mainz, Germany
- Graduate School Materials Science in Mainz, Staudinger Weg 9, D-55128, Mainz, Germany
| | - Ramsia Sreij
- Department of Chemistry Physical and Biophysical Chemistry (PC III), Bielefeld University, D-33615, Bielefeld, Germany
| | - Riande I Dekker
- Debye Institute for Nanomaterials Science, Utrecht University, NL-3584 CC, Utrecht, The Netherlands
| | - Maximilian Hofmann
- Institute of Physics, Johannes Gutenberg University, D-55099, Mainz, Germany
| | - Thomas Palberg
- Institute of Physics, Johannes Gutenberg University, D-55099, Mainz, Germany
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