conference in Queensland in February addressed issues such as the design of nano-electrocmechanical devices and the creation of new materials atom by atom. These spectacular advances in minuscule technology are ushering in the quantum age and a new era of building revolutionary materials and devices out of individual atoms and particles, transforming manufacturing.
Retractable walls, floors that automatically clean themselves, and paints that can change colour according to the temperature are just some of the possibilities of nanotechnology’s future impact on building materials.
A definition of nanotechnology is the manipulation of matter on the nanoscale, says Professor Michael Cortie, director of the Institute for Nanoscale Technology at the University of Sydney. “It’s technology that invokes the special properties of matter at the scale of one to 100 nanometres.”
Nanotechnology has already made an impact in paint and coating systems and in solar glazing coatings for glass, Cortie notes. “There has been history of nano-science in paint but with the advent of modern scientific techniques of measurement, people have really been able to exploit this to produce white, more opaque paints - paints that are more resistant to UV degradation.
“There’s a quest on to develop paints that are both dark to our eye and yet heat-rejecting, which is counter intuitive,” notes Cortie. Lehmann Pacific Solar makes Skycool, a paint that’s heat-rejecting and paints that change colour according to the temperature are being developed in Germany.
Glass coatings are another area where nanotechnology has been successfully applied, including products from Pilkington and G James Glass. “The ideal is a coating where in the summer all the infra-red light from the sun is rejected but all the visible light is transmitted,” Cortie explains. “No product does this perfectly, but if you pull this off, you get half the heat, but all the light. For example, if you have a thick piece of silver or gold, it’s opaque to light but when you shrink it down to about 10 nanometre thickness, it’s transparent to visible light and reflects infra-red falling on it.”
Glass coatings such as these were available in the 1960s and 1970s, but according to Cortie were aesthetically unacceptable. “People didn’t like their strong colours,” he says. “It was ok if you were indoors because you had a grey light, but from the outside they were very yellow or green. The current nanotechnology for glass aims for a neutral colour outside and inside. They’re cheaper, but less efficient so it’s a trade off.”
The CSIRO and University of Technology in Sydney showcased a number of commercially available products and computer simulations of the application of nanotechnology in the home, with their ‘nanohouse’, The Glass House, built for the houses of the future project, part of the 2004 Year of the Built Environment. This house incorporated Pilkington’s Activ glass, which has a transparent exterior coating developed using nanotechnology that utilises natural UV light and rain to keep the glass free from organic dirt. Using a photocatalytic process, the coating reacts with UV rays from daylight to break down and disintegrate dirt. Because the glass is hydrophilic, when rain or water hits it, instead of forming droplets, the water spreads evenly over the surface and as it runs off, takes the dirt with it.
Now quantum nano-science is taking things further as the Sir Mark Oliphant Conference on Frontiers of Quantum Nanoscience indicated by looking at the possible effects of quantum nano-science on society. “It’s about what happens when the familiar laws of physics are replaced by quantum laws, as you move below the level of molecules and atoms,” Professor Gerard Milburn of the University of Queensland explains. “It could result in houses repairing themselves from earthquakes or similar damage.”
Carbon nanotubes used in tennis racquets could transfer to the building industry, Cortie says. “You could pay the price for a composite material and have a polymer matrix and you’d have very high-strength struts, beams, tubing and so on for lightweight construction.” However, because it is a polymer it would not do well in sunlight or be recommended in load-bearing applications.”
Another area in which nanotechnology could benefit the industry is in metallic framing, Cortie says. “There are ways of producing extrusions and other highly cold-worked products that give them incredible strength and toughness. You could even contemplate producing more lightweight buildings with metallic frames.”- Katrina Fox.