Featured Research

from universities, journals, and other organizations

Emulsion With A Round-trip Ticket

Date:
June 18, 2007
Source:
John Wiley & Sons, Inc.
Summary:
A British team reports a double inversion of a nanoparticle-containing emulsion: By the successive addition of a surfactant, they were able to convert an oil-in-water emulsion into a water-in-oil emulsion, and then back again.

Oil and water are not miscible. However, it is possible to combine both into an emulsion in which they act as a unit—for example, in creams, body lotion, milk, or mayonnaise. In these substances, one of the two liquids is dispersed as tiny droplets in the other, which requires an emulsifier and vigorous shaking or stirring.

Related Articles


Whether the oil droplets are suspended in water (oil-in-water emulsion O/W) or the water droplets are suspended in oil (water-in-oil emulsion W/O) depends on various factors. In the journal Angewandte Chemie, a British team from the University of Hull now reports a double inversion of a nanoparticle-containing emulsion: By the successive addition of a surfactant, they were able to convert an O/W emulsion into a W/O emulsion and then back again.

The emulsifier’s job is to make droplet formation easier and to counteract separation. In addition to surfactants (substances contained in detergents and the like), fine solid particles also have a stabilizing effect. Mustard powder has thus long been used to stabilize mayonnaise. Both surfactants and particles aggregate at the phase boundary of the two liquids and keep the droplets from flowing together. Many commercial formulations contain surfactants as well as solid particles.

If the conditions are changed, a phase inversion can occur, converting an O/W into a W/O emulsion, for example, if more and more surfactant is added. This is no great feat. However, Bernard P. Binks and Johnny A. Rodrigues have now achieved something astonishing: a double inversion. Their system initially contains silica nanoparticles and a small quantity of a surfactant with a water-loving (hydrophilic), positively charged head and two nonpolar, water-repellent (hydrophobic) tails.

The tiny silica spheres are negatively charged, hydrophilic, and easily wettable by water. In this state, they stabilize oil drops in water (O/W). If more surfactant is added, a layer of surfactant molecules surrounds each sphere, all with their hydrophobic tails sticking out. The spheres are now covered with a hydrophobic layer and are no longer wettable. They stop repelling each other and begin to aggregate.

This causes the emulsion to undergo its first inversion into W/O. If further surfactant is then added, these additional molecules lodge tail-to-tail with those already surrounding the spheres. This forms a double layer around the spheres, with the positively charged heads of the second surfactant layer now sticking out. The spheres thus once again have a charged, hydrophilic surface and again stabilize oil droplets in water. The emulsion undergoes its second inversion back into O/W.


Story Source:

The above story is based on materials provided by John Wiley & Sons, Inc.. Note: Materials may be edited for content and length.


Cite This Page:

John Wiley & Sons, Inc.. "Emulsion With A Round-trip Ticket." ScienceDaily. ScienceDaily, 18 June 2007. <www.sciencedaily.com/releases/2007/06/070614114147.htm>.
John Wiley & Sons, Inc.. (2007, June 18). Emulsion With A Round-trip Ticket. ScienceDaily. Retrieved October 23, 2014 from www.sciencedaily.com/releases/2007/06/070614114147.htm
John Wiley & Sons, Inc.. "Emulsion With A Round-trip Ticket." ScienceDaily. www.sciencedaily.com/releases/2007/06/070614114147.htm (accessed October 23, 2014).

Share This



More Matter & Energy News

Thursday, October 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

3D Printed Instruments Make Sweet Music in Sweden

3D Printed Instruments Make Sweet Music in Sweden

Reuters - Innovations Video Online (Oct. 23, 2014) Students from Lund University's Malmo Academy of Music are believed to be the world's first band to all use 3D printed instruments. The guitar, bass guitar, keyboard and drums were built by Olaf Diegel, professor of product development, who says 3D printing allows musicians to design an instrument to their exact specifications. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Chameleon Camouflage to Give Tanks Cloaking Capabilities

Chameleon Camouflage to Give Tanks Cloaking Capabilities

Reuters - Innovations Video Online (Oct. 22, 2014) Inspired by the way a chameleon changes its colour to disguise itself; scientists in Poland want to replace traditional camouflage paint with thousands of electrochromic plates that will continuously change colour to blend with its surroundings. The first PL-01 concept tank prototype will be tested within a few years, with scientists predicting that a similar technology could even be woven into the fabric of a soldiers' clothing making them virtually invisible to the naked eye. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Jet Sales Lift Boeing Profit 18 Pct.

Jet Sales Lift Boeing Profit 18 Pct.

Reuters - Business Video Online (Oct. 22, 2014) Strong jet demand has pushed Boeing to raise its profit forecast for the third time, but analysts were disappointed by its small cash flow. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
Internet of Things Aims to Smarten Your Life

Internet of Things Aims to Smarten Your Life

AP (Oct. 22, 2014) As more and more Bluetooth-enabled devices are reaching consumers, developers are busy connecting them together as part of the Internet of Things. (Oct. 22) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins