by Staff Writers
Zurich, Switzerland (SPX) Jun 20, 2017
Researchers led by Lucio Isa, Professor of Interfaces, Soft Matter and Assembly at ETH Zurich's Department of Materials, have created a new type of silica particle able to stabilise emulsions in a new way. An emulsion is a finely dispersed mixture of two immiscible liquids, constituted by droplets of one liquid dispersed in the second one.
An everyday example of this is a salad dressing made of oil and vinegar: its main constituents, vinegar (effectively water) and oil, do not mix on their own and must be whisked vigorously to create a uniform mixture. If this mixture is left to stand, the finely dispersed vinegar droplets will fuse together again and the liquids will separate out completely.
This is why it is necessary to stabilise emulsions; this can be achieved using numerous different emulsifiers, such as surfactants, polymers or proteins. As early as in the beginning of the 1900's, the British chemists W. Ramsden and S. U. Pickering also demonstrated that emulsions could be stabilised using very fine solid particles, such as spherical silica particles (SiO2).
In this process, the particles spontaneously enter and bind to the interface between the two liquids. They form a sort of armour around the droplets and prevent their fusion, thus stabilising the emulsion practically indefinitely. However, until now, this required two types of particles: those with hydrophilic surfaces, i.e. mostly sitting in the water, that stabilise only oil-in-water emulsions and those with hydrophobic surfaces, i.e. mostly sitting in the oil, that stabilise only water-in-oil mixtures.
One emulsifier stabilises both emulsions
In a study recently published in Nature Communications, the researchers have demonstrated that they can stabilise both types of emulsion using just one type of these raspberry-shaped particles.
This depends solely on the liquid into which the particles are introduced before the emulsion is formed. If the researchers add the particles to the oil phase, a water-in-oil emulsion is formed. Conversely, they are able to stabilise an oil-in-water emulsion (oil droplets finely dispersed in water), if they dissolve their new particles in water first. "These particles can therefore be used as a universal tool for creating emulsions," says Isa.
Coarse particles get stuck earlier
With their raspberry-shaped particles, Isa and his colleagues have laid the foundation for further research in this area, and they have filed a patent for their new process of particle production as emulsion stabilisers.
New applications in sight
in the chemical industry. Even though this research was focused on laboratory model systems, the same principles can be extended to the use of naturally occurring rough particles as emulsion stabilisers, to find other potential uses in the food, cosmetics and pharma industry, even though further research is needed in this direction.
Washington DC (SPX) Jun 21, 2017
Chemical reactions necessarily involve molecules coming together, and the way they interact can depend on how they are aligned relative to each other. By knowing and controlling the alignment of molecules, a great deal can be learned about how chemical reactions occur. This week in The Journal of Chemical Physics, from AIP Publishing, scientists from Aarhus University in Denmark and the In ... read more
Space Technology News - Applications and Research
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement|