A new nanocomposite material discovered by researchers at Rice University has the intriguing property of getting stronger from repeated stress. The material is made from verticaly aligned nanotubes combined with polydimethylsiloxane (PDMS), an inert, rubbery polymer. After repeated compression (3.5 million cycles over a period of about a week), the material was found to be 12 percent stiffer than its original state.