Belgian scientists have discovered a new method to stop nanoparticles sticking together. The method will improve the use of nanoparticles in applications ranging from suncream to catalysis, they claim.

A nanoparticle's small size and large surface area give it improved properties over bulk solids in a number of applications. But nanoparticles have a tendency to aggregate, which reduces their surface area and makes them behave more like the bulk material. A magnetic field could solve the problem, claim Johan Martens and colleagues at the Catholic University of Leuven.

The magnetic field breaks up the aggregates, forming nanoparticles a fraction of the size

Martens suspended alumina and silica aggregates in a flowing solution within a stationary magnetic field. They found that the magnetic force broke up the aggregates, forming particles a fraction of the size.

According to Martens, the new dispersion method is simpler and more energy efficient than commonly used methods, such as ball milling and ultrasound.

'This is an important breakthrough for many of the real industrially relevant applications of nanomaterials,' says Luis Liz-Marzán, an expert in nanoparticles from the University of Vigo, Spain. 'It is a very elegant and efficient way to improve all these processes.'

Martens says the group plan to use the method to optimise particle dispersion in heterogeneous catalysis and pharmaceutical formulations.

Sophia Anderton

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