Credit: © 2009 Wiley

The mechanical properties of nanostructures relate to the performance of materials based on such structures and there are various ways to probe their behaviour. Scanning probe techniques can measure the mechanical properties of individual nanostructures, but they are tedious and time consuming. By looking at how filamentous nanostructures fragment when sonicated, researchers at the University of Cambridge now show that the limiting length of the nanostructures after prolonged sonication is correlated to their effective breaking strength1.

To understand how sonication can cause nanostructures to fragment and eventually plateau at a certain length, Eugene Terentjev and colleagues created a theoretical model to predict this limiting length by exploring the tensile forces acting on a nanofilament nearby an imploding bubble. Because the tensile stress on the filament decreases with shorter filaments, the researchers were able to determine an equation that ties the limiting length to the diameter of the filaments and the tensile stress. Using the equation, which is strictly for sonications in low viscosity solvents, the limiting length and tensile strength predicted for carbon nanotubes, protein fibrils and silver nanowires compared well with experimental data.

The model predicts an average strength of the nanofilaments and does not consider other effects from cavitation, such as bending. Nevertheless, using sonication-induced fragmentation could be an alternative way to determine the tensile strength of nanofilaments.