Wednesday, January 20, 2010


Sunday, January 17, 2010

Plastic Coating Makes Environmentally Deleterious Soap Superfluous

The right side of a mirror has a polymer coating that fights fogging — making the camera visible — and helps wash away oil.

IMAGINE how great it would be if, after dinner, you could stack the greasy dishes, pots, pans and utensils in the sink and let plain old water rinse away the grime — with no help from detergents, and little or no scrubbing. Bye-bye, dishpan hands.

Plastic coatings under development may someday bring that moment to pass, rendering dinnerware, bathroom mirrors and even factory equipment sparkling clean with water alone.

The new materials may be appreciated not only by dish-washing family members, but also by environmentalists concerned about all of the soap that disappears down the drain. Detergents that end up in wastewater can cause algae to bloom, among other effects.

“We want to cut soap out of the equation for cleanup,” said Jeffrey P. Youngblood, an associate professor of materials engineering at Purdue University in West Lafayette, Ind.

In experiments, Dr. Youngblood and his colleagues attached the coatings chemically to the surface of glass. But he is now working on polymer additives for liquids that can be poured into a spray bottle, for example, and then used to clean mirrors and even eyeglasses or goggles.

Scientists call the coatings self-cleaning because, once they are applied to a surface, they do much of the work of scrubbing away oily residue — like that from a greasy fingerprint. “The oil beads up and then the water moves under the oil, lifting it up so it floats away,” said Kirsten Genson, a postdoctoral researcher in Dr. Youngblood’s group.

Getting the coating to do this is ingenious, said Michael F. Rubner, a professor of polymer materials science and engineering, and director of the Center for Materials Science and Engineering at the Massachusetts Institute of Technology. “Jeff figured out a way to have molecules on the surface that can rearrange themselves so they can self-clean, rejecting grease,” he said.