Developments to Watch
THE WONDERS OF A TWO-FACED MOLECULE
THE NEEDLE-AND-THREAD technology being spun at the University of Illinois has nothing to do with what's in grandma's sewing basket. Scientists use it to stitch materials on the molecular scale, using elongated molecules stiff on the "needle" end but soft like thread at the other. The molecules are only 0.01 micron long, so you would need a necklace of 275 to circle a human hair.
What's almost magical, says chemist Samuel Stupp, who heads the research team, is that the needle ends are drawn to each other like magnets, and the soft ends also clump together. The result: The molecules "self-assemble," clustering in parallel by the millions to create an ultrathin polymeric film that can have totally different properties on either surface. For instance, engineers could make one side sticky and the other slick. Such a film, Stupp suggests, could be rolled into artificial arteries whose outside would adhere to surrounding tissue--yet inside, blood would flow freely. Or each side could be tailored to stick to different materials, leading to composite panels for aircraft and car bodies even sturdier than today's tougher-than-steel composites. 3M Co. says the needle-and-thread approach is very clever and may promise a new generation of superfilms.EDITED BY NEIL GROSS