(Nanowerk News) Small-angle scattering of x-rays and neutrons is a useful tool for studying the structure of molecules and nanoparticles. So far, however, experiments have revealed a surprising lack of nanoparticle structure in certain nanocomposite materials – those whose molecular framework is strengthened by nanoparticles previously treated by polymer adsorption.
In the new approach detailed in EPR E (“In the absence of structural factors in concentrated colloidal suspensions and nanocomposites”), Anne-Caroline Genix and Julian Oberdisse at the University of Montpellier, France, demonstrated that these patterns could only be generated through attractive interactions between nanoparticles of various shapes and sizes.
The duo’s results highlight the rapidly increasing capabilities of small-angle scattering instruments, and may also help researchers improve their techniques for studying nanocomposites – with applications in fields including miniature electronics, biological tissue engineering, and strong, lightweight materials for aircraft.
When the x-ray or neutron beam interacts with atoms in a sample of material, the resulting transfer of momentum causes them to scatter in a characteristic pattern, which varies depending on the molecular structure of the sample. In recent years, instruments for measuring this scattering have improved greatly, offering faster data acquisition, as well as more accurate and extensive measurements of changes in particle velocity and direction.
In their recent work, Genix and Oberdisse have used this technique to study the structure of concentrated polymer-based nanocomposites. It is known that at high concentrations of nanoparticles, the interactions between the particles change the scattering pattern.
But to their surprise in their experiments, the two found that this did not appear to be the case: instead, the scattering patterns of x-rays they observed seemed to indicate individual nanoparticles. To explain these results, the researchers performed numerical simulations to relate the position of the nanoparticles in space to the scattering patterns they observed.
They found that for high concentrations of nanoparticles, the attractive interactions between nanoparticles of various shapes and sizes produce a nearly ‘structureless’ state in the nanocomposite – explaining the lack of specific features in their observations. This discovery offers important insights into the molecular properties of nanocomposites and how they can be engineered to optimize their unique properties.