W Washington, Dec 13 : It won't be long before there will be a face mask that may change its shape to fit any user, or a lens that does the same, for scientists have developed a new class of shape-memory rubber, that can be stretched to a new shape and regain its original shape when heated.
 This rubber, developed by the researchers at the University of Rochester, may enable applications as diverse as biomedical implants, conformal face-masks, self-sealing sutures, and "smart" labels. This unique invention owes its credit to Mitchell Anthamatten, assistant professor of chemical engineering and inventor of the material. After stretching to any desired shape, these materials, also known as shape-memory polymers, when heated will revert to their initial shape. These materials, unlike conventional shape-memory polymers are however transparent, rubbery, and most importantly, will allow engineers to control the speed at which it returns to its original shape. The other shape memory polymers utilize crystallization to hold a temporary shape, which often makes them opaque, hard, and brittle in their frozen states, which limits their use. "At higher temperatures the material stretches like a rubber band, but, at lower temperatures, it stiffens up," said Mitchell Anthamatten. He added: "This property can be used to temporarily hold the material in a deformed shape; and its original shape can be recalled by heating. Imagine an optical lens that can be triggered to change shape, a face-mask that can fit any user, or a biomedical implant that changes shape slow enough for a surgical procedure." This new rubber has different functioning than conventional shape-memory materials by using "sticker groups"-hydrogen bonding groups that form temporary bonds. Such sticker groups break and reform constantly. It's same as tearing a net apart only to discover new knots that have been formed between different strands. As the material is stretched, new bonds are formed that hold the material, temporarily, in its deformed shape. The rate at which the rubber returns to its original shape can be controlled through creating the rubber with varied amounts of sticker groups. Because of this control, Anthamatten foresses applications, that today's shape-memory polymers simply can't fulfill. "The pressure at which you hold together a sutured wound determines a lot about how it will heal," said Anthamatten. He added: "This polymer could be made into a thread that responds precisely to body temperature, tightening the sutures to the perfect pressure." This unique discovery was described in the journal Advanced Materials. (ANI) © 2007 ANI TAGS: Tech 
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