Engineering Office of the Dean


Nanoparticles: microscopic size, huge potential

Professor George Simon says microscopically small nanoparticles have a potential well beyond their size. He is looking to modify their diverse functional properties to make plastics and other exciting applications. He is also interested in their incorporation into polymers to make nanocomposites, as well as related areas, such as biomimetics (bringing methods found in nature to modern technology) and self-healing materials.

You can define a nanomaterial as a nanoparticle if at least one of its dimensions is the size-scale of a nanometre: around 10 atoms thick. Nanoclay is an example and is one of the materials that George has had a long interest in.

Nanoclays are one nanometre-thick platelets with the ability to make plastics tougher and more gas or solvent-impermeable. George says these and related materials are of much interest in the aerospace and automotive industries. These industries use composite materials - or materials comprising plastic and another component - and George thinks adding further nanoparticles to toughen their composites would be very useful.

'Some work in nanoclay and epoxy adhesives produced materials which were rigid and strong, but also tough. This was a good result, because making materials rigid usually makes them brittle,' George says.

'The nanoclay also helped them become more flame-retardant. If you use nanoclays with other composites, such as glass or carbon fibre, we found that the clay, which sits between the fibres, can also toughen the composites.'

George has also moved into the area of functional nanoparticles. Carbon nanotubes are a particular area of interest, as only low concentrations of these are required for conductivity. A carbon nanotube is a chicken wire-shaped arrangement of carbon atoms, rolled into a cylindrical shape. They have strong thermal, mechanical and electrical properties and are ideal for a variety of applications. George has studied the electron emission of nanotubes as a potential way to develop lower energy lighting.

George is also increasingly using electrospinning, a technique that uses a high-voltage electrical charge to break down a drop of polymer solution and stretch the molecules into a nanometre-diameter fibre. George says this has had benefits in the medical industry; he and a number of his department colleagues have been using it for a range of regenerative medicine applications. In collaboration with ANU, he used it to produced improve hip implant surfaces.

'Electrospinning can be used to make scaffolds for tissue engineering applications,' George says. 'You tend to use biodegradable matrices, because if these nanofibre mesh networks are placed in the body, you want them to biodegrade while the cells proliferate. We're also looking at other ways to make useful nanofibres that don't need high voltages.'

George's decade of nanomaterials research follows 20 years of work with plastics and polymer blends. He was recently involved in researching starch-based polymers to make biodegradable plastics.

'My Research Fellow and I were involved with colleagues from CRC for Polymers and RMIT on a project with Plantic, an Australian company that uses starch from things such as corn to make plastics,' George says. 'These plastics come from renewable resources and are fully biodegradable, and we were looking to improve their properties. You can use these materials to make a plastic that you can form into shapes using conventional plastic processing equipment.' He currently has a project with the CSIRO looking at making fully biodegradable nanocomposites using nanofibres of cellulose grown by microbes.

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