Indian origin scientist creates oil resistant materialDecember 7th, 2007 - 6:45 pm ICT by admin
Washington , Dec 7 (ANI): A team of engineers led by an Indian origin scientist at Massachusetts Institute Of Technology has devised a simple process to manufacture materials that have a high tendency to repel oil and can be applied as a flexible surface coating.
The process, state the researchers, may find its use in aviation, space travel and hazardous waste cleanup.
The study was led by Anish Tuteja, a postdoctoral associate in MIT’s Department of Chemical Engineering.
This material may be used to help in protecting parts of airplanes or rockets that are susceptible to damage from being soaked in fuel, such as rubber gaskets and o-rings.
These are vulnerable points in many aerospace applications. It would be nice if you could spill gasoline on a fabric or a gasket or other surface and find that instead of spreading, it just rolled off, said Robert Cohen, the St. Laurent Professor of Chemical Engineering.
It was challenge for scientists to create a strongly oil-repelling, or oleophobic material and the natural variants of such a material are unknown.
Oils and other hydrocarbons have the tendency of to spread out over surfaces due to their very low surface tension (a measure of the attraction between molecules of the same substance) unlike water that has a very high surface tension and tends to form droplets.
For example, beads of water appear on a freshly waxed car (however, over a period of time, oil and grease contaminate the surface and the repellency fades).
Researchers overcame the surface-tension problem by designing a material composed of specially prepared microfibers that essentially cushion droplets of liquid, allowing them to sit, intact, just above the material’s surface.
When oil droplets land on the material, resembling a thin fabric or tissue paper, they rest atop the fibers and pockets of air trapped between the fibers.
The contact angle between the droplet and the fibers is large, preventing the liquid from reaching the bottom of the surface and wetting it.
These microfibers are a blend of a specially synthesized molecule called fluoroPOSS, which has an extremely low surface energy, and a common polymer.
These can be readily deposited onto many types of surfaces, including metal, glass, plastic and even biological surfaces such as plant leaves, using a process called electrospinning.
Scientists have also developed some dimensionless design parameters that may help in predicting the stability of oleophobicity or oil-resistance between a particular liquid and a surface.
The design equations are based on structural considerations, especially the re-entrant nature (or concavity) of the surface roughness, and on three other factors: the liquid’s surface tension, the spacing of the fibers, and the contact angle between the liquid and a flat surface.
After making use of these relationships, the researchers would be able to design fiber mats that are optimized to repel different hydrocarbons.
They have already created a non-woven fabric that can separate water and octane (jet fuel), which they believe could be useful for hazardous waste cleanup.
The Air Force, which funded the research and developed the fluoroPOSS molecules, is interested in using the new material to protect components of airplanes and rockets from jet fuel.
The study was published in Science. (ANI)
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