Researchers at Rice University have created a synthetic material that grows stronger through repeated applications of tension, just as the bones and muscles of the body become stronger with repeated workouts.
Work done in the lab of Pulickel Ajayan, professor of chemistry and mechanical engineering and materials science, shows the potential of polymer-based nanocomposites filled with carbon nanotubes. The team reported the discovery this month in the journal ACS Nano.
The trick, it seems, lies in the complex and dynamic interface between nanostructures and polymers in carefully engineered nanocomposites.
Brent Carey, a graduate student in Ajayan's lab, discovered this interesting property during a check of the high-cycle fatigue properties of a compound he made by infiltrating a forest of vertically aligned multi-walled nanotubes with polydimethylsiloxane (PDMS), a polymer inert rubber. To his surprise, repeatedly putting a load on the material did not seem to damage it at all. In fact, the stress made him more resistant.
They also observed something else about this unique phenomenon: compressing the material did not change its properties; only dynamic stress, that is, deforming it over and over again, made it stronger.