Pound for pound, spider silk is one of the strongest materials in the world; it’s about five times stronger than a piano wire – and a piano wire has to put up with a lot of pressure. Researchers have long tried to develop materials which mimic the remarkable properties of spider silk, but only now did Arizona scientists announce that they are able to obtain a wide variety of elastic properties of the silk of several intact spiders’ webs using a sophisticated laser light scattering technique.
“Spider silk has a unique combination of mechanical strength and elasticity that make it one of the toughest materials we know,” said lead researcher Jeffery Yarger of Arizona State University’s Department of Chemistry and Biochemistry, in a statement. “This work represents the most complete understanding we have of the underlying mechanical properties of spider silks.”
Scientists used extremely low power lasers (less than 3.5 milliwats) and aimed it at spider webs. Using this novel approach, they were able to actually map the stiffness of each web without disturbing it; they found variations among discreet fibers, junctions, and glue spots.
They studied webs from four different spider species: Nephila clavipes, A. aurantia (gilded silver face), L. Hesperus (western black widow) and P. viridans (green lynx spider) – all with remarkable silk properties. But they didn’t only study the stiffness, they also studied a property that spider silk displays, called supercontraction – a property unique to spider silk. Basically, it soaks up water when exposed to high humidity, and this absorbed water can lead to shrinkage in an unrestrained fiber-up to 50 percent. However, even in these conditions, spider silk is still versatile, and supercontraction helps the spider tailor the actual properties of the silk it produces during spinning.
“This study is unique in that we can extract all the elastic properties of spider silk that cannot and have not been measured with conventional testing,” said Yarger.
This new study could pave the way for new biomaterials to create tronger, stretchier, and more elastic materials.