Breaking the nanostructure mould

Researchers at the University of Minnesota have developed a process for producing nanoscale cubes and spheres using the controlled disassembly of larger, lattice-like structures. This could make the production of more uniform porous nanostructures simple and controlled.

Most conventional methods for the production of porous silicon dioxide nanoparticles suffer from the fact that the growing particles tend to aggregate, making it difficult to achieve a uniform size. The shape of the particles is also difficult to influence.

The Minnesota team chose a backward approach, first building up a lattice structure of silicon dioxide and then disassembling it to get the shape they wanted.

The ‘moulds’ used for the lattice were tiny spheres of the plastic polymethylmethacrylate (PMMA), which assemble themselves through closest packing of spheres into a colloidal crystal. Between the spheres in this structure, there are tiny approximately tetrahedral and octahedral spaces.