In "switchable adhesives," body heat makes all the difference
AMHERST, Mass. -- A team of French scientists is developing a coating that's sticky when a person touches it, but almost immediately cools to a slick, Teflon-like surface when the person lets go. University of Massachusetts polymer scientists Thomas Russell and Ho-Cheol Kim reviewed the findings in a recent issue of the journal, Science.
"We can all recall situations when the stickiness of a substance -- such as chewing gum or partially dried paint -- results in an unpleasant experience," the UMass scientists wrote. "But there are numerous situations where tack is highly desirable. Adhesive tape, rubber cement, and Post-It notes all use tack to great advantage." Industries which rely on adhesives include cosmetics, aerospace, and textiles, Russell noted. The sticky substances may be natural, such as starches or natural rubber cements, or synthetic polymers -- long strings of linked molecules.
"Worldwide, the production and use of adhesives and tackifiers support an industry that nets tens of billions of dollars annually," Russell said. However, he added, it remains difficult to produce a material that is sticky only at certain times. Thus, the ability to trigger specific levels of tack holds tremendous potential. The French scientists accomplished this by manipulating an adhesive polymer so that its level of tackiness would rely only on the rise or fall of a few degrees, according to the journal.
One of the potential uses of this switchable tackiness would be in self-cleaning tennis racquets and golf club grips, Russell said. Grips coated with this polymer would be tacky under the hands' warmth, but after the grip is released, the lower temperature would "switch off" the polymer's tacky properties. As the surface cools, it becomes smooth and slick, enabling dust and dirt to fall away.
Note: Thomas Russell can be reached at 413-577-1516 or russell@iskra.pse.umass.edu
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Science