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Saturday26 July 2014

Material world

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Amanda Birch uncovers four cutting-edge materials set to revolutionise buildings of the future and, opposite, investigates how practices discover and apply scientific innovations

Nanogel

It sounds like the stuff of science fiction. Nanogel — a silicon-based transparent material that resembles tiny polystyrene beads, repels water and has made it into the Guinness Book of Records for being the least dense solid in the world — is now being used in buildings for its incredible insulating properties.

What is it This translucent silicone gel consists of tiny spheres of bonded silicon (5%) and oxygen atoms (95%) joined into long strands separated by pockets of air.

How it was developed Invented in the 1930s by Steven Kistler, a scientist at the College of the Pacific in California, it was later used by Nasa to insulate spaceships against extremely cold temperatures. Nanogel is now used as an insulation for facade systems.

It also absorbs sound, resists moisture, but transmits light.

Chemical and materials company Cabot has been developing this material for 12 years. Jim Satterwhite, business manager of Cabot’s Nanogel division, says that the manufacturing process had previously been dangerous and expensive. When a breakthrough came about, Cabot purchased the patent and set about modifying and removing ethanol, the dangerous element, from the manufacturing process.

“You end up with an insulation material which is extremely hydrophobic which makes it excellent for fenestration systems,” says Satterwhite.

“Its other unique property is that it is almost transparent. In insulated glass, Nanogel can significantly improve its thermal performance without a compromise on light transmission.”

Where it’s being used Since 2001, Cabot has used it for four different facade systems. There are about 25 projects in the US using the material and some 60 projects in the pipeline in Europe. The first project in the UK to use Nanogel embedded in the facade is an office development in Leeds by Atkins.

Nanogel is sold on a volumetric basis and costs about £1,400 per cubic metre.

Details james_satterwhite@cabot-corp.com

Synthetic spider silk

The unique qualities of spiders’ silk has been the inspiration for a new man-made material that could be used as tensile cables in buildings.

What is it Scientists working in the field of biomimetics are investigating how to mimic the properties of spider silk and the way it is spun so a new material can be created and used in the field of construction.

How it is developed Fritz Vollrath of the Zoology department at Oxford University and David Knight, consultant scientist of Oxford Biomaterials and Spintec, are leaders in how spider silks are processed and are researching a synthetic material to imitate this.

Knight says that this new material couldn’t be protein-based like spider’s silk as it would be expensive and vulnerable to bacterial deterioration. Instead, the way forward is using repetitive block polymers. Little blocks of polymer would be repeated like spider silk to produce a material much lighter and six times stronger than a steel cable.

A spider can make up to 11 different types of silk depending on the species. The most interesting is the dragline, which spiders use for scaffolding their webs and for pulling themselves along. It is incredibly tough and will soak up huge amounts of energy before it fails. The energy absorbency of a spider web could stop a car travelling at full speed with a strand of fibre as thick as a pin.

A polymer good at dissipating energy and with similar elastic properties to spider silk could be available within three years.

Details 01962 853 637.

Macro Fibre

Imagine a small ceramic patch that can be used as an early warning device for monitoring a bridge’s durability. Sound implausible?

What is it This innovative new material called Macro Fibre Composite is a rectangular-shaped patch consisting of a very thin (180 microns) piezo ceramic plate that is embedded with electrodes that are connected to wires. Piezo fibres expand or contract if a voltage is applied, so when the patch is connected to a power supply, the flexible material will expand or contract without cracking. Conversely it can generate a voltage when a force is applied.

How it was developed MFC combines the piezo-electric properties of ceramic with the robustness of plastic to ensure the patch doesn’t break. Piezoelectric ceramic material was invented by the Americans and British in the 1930s and used during WWII to detect German submarines using underwater ultrasound. Thomas Daue, founder of materials supplier Smart Materials, bought the Nasa licence and together with other industry partners has altered the manufacturing process to make it commercially viable. The MFC patch is available in several sizes starting from 2.8cm x 1.4cm and stretches to a maximum of 8.5cm x 5.7cm.

Where it’s being used MFC has only been available for two years but already the number of applications for this fantastic little patch are multiplying. It is being researched for use by Smart Materials partner Volkswagen. MFC patches are bonded on to the roof of a car and as the car moves and the roof begins to shake the MFC patch contracts, bends the roof and absorbs vibrations. By preventing roof movement it reduces noise .

In the construction sector, MFC patches can be bonded to critical points of a bridge and the move-ment of the bridge will cause the MFC to expand and contract. The MFC creates a voltage or charge and this charge can be read using a monitoring device. MFC could therefore be used as an early warning device to monitor a structure. The smallest MFC patch costs £28.

Details www.smart-materials.com

Litracon concrete

Translucent concrete or Litracon has already beguiled architects such as Norman Foster, Jean Nouvel and Herzog & de Meuron and it may soon be attracting others if plans to produce it on a large scale go ahead.

What is it Litracon is similar to conventional concrete in consistency and appearance, says its creator, Hungarian architect Aron Losonczi. It consists of glass fibres supplied by Schott measuring 70 micrometres in diameter. The fibres are laid within the concrete and are not visible in the completed product. The material resembles rice paper or a Japanese sliding screen with shadows of objects or people showing through it.

How it was developed Losonczi worked with scientists at the Technical University of Budapest to develop his material in 2001. It was inspired by a glass and concrete sculpture he saw in Hungary, but instead of inserting large pieces of glass into concrete as shown in the sculpture, Losonczi used glass fibres for his prototype.

Where it’s being used Losonczi anticipates his material being used for both interior and exterior applications and it could be supplied as blocks or panels up to 20m thick .

Given that Litracon is still only made by hand from a small work-shop in Csongrad, southeast of Budapest, the applications are limited and experimental. It has just been used for its first exterior project, a 4m high, 3.5sq m statue at a park near Budapest; and it may be used for the interior walls in the new Hungarian embassy in Washington, DC by Hungarian architects Antal and Veronika Lazar and Zoltan Sukosd. At present Litracon costs £830-£1,050 per square metre.

Details www.litracon.hu

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