Tiny 'hairy' materials boon for renewable energy markets

In ground-breaking research, scientists at the US Department of Energy have developed a new technique to grow tiny 'hairy' materials that assemble themselves at the microscale.

Like the way Chia Pets (terracotta figurines) grew in commercials, this wonder material can lead researchers to grow many different shapes - short forests of dense straight hairs, long branching strands or 'mushrooms' with tiny pearls at the tips.

What are the advantages?

Scientists are very interested in materials with tiny fibres for technologies like batteries, photovoltaic cells or sensors.

'Hairy' materials offer up a lot of surface area. Many chemical reactions depend on two surfaces making contact with one another, so a structure that exposes a lot of surface area would speed the process along.

"The process is very simple, the materials are cheap and available and they can grow on almost every surface we've tried," said physicist Igor Aronson who is associated with US Department of Energy's Argonne National Laboratory.

For example, grinding coffee beans gives the coffee more flavour than soaking whole beans in water. Micro-size hairs can also make a surface that repels water, called superhydrophobic, or dust, the study added.

The key ingredient is epoxy which is added to a mixture of hardener and solvent inside an electric cell.

Then the scientists run an alternating current through the cell and watch long, twisting fibres spring up.

"This is a completely new kind of polymer. With this method, you can support more complex structures that have unique properties," said Argonne physicist Alexey Snezhko.

Currently, the primary methods of creating interesting shapes at small scales is lithography - a type of 'printing' where researchers lay a pattern on the material and the rest of it is melted or etched away.

But it's hard to make very complex structures with this method and the results are not always uniform.

"The new polymers assemble themselves which is much easier and less labour-intensive than lithography," explained Snezhko.

The polymer could be incorporated into semiconductor-based renewable energy technologies.

It also proved that it could survive high temperatures, up to 150 degrees Celsius - an essential property for many manufacturing processes.