This week’s fascinating chemical is (poly) ethylene tetrafluoroethylene (ETFE). ETFE is a type of polymer (which in this case refers to plastics) that is closely related to two other, well-known polymers: polytetrafluorethylene (PTFE), better known as Teflon, and polyethylene (PE), which is used in everything from plastic bags to pipes. Polymers are very long molecules with a chain-like structure made up of many links called monomers. ETFE is related to these other two plastics because its chain consists of an alternating pattern of the monomers used to make both PTFE and PE.
ETFE was originally developed by DuPont in the 1970’s for use as insulation material in the aerospace industry. However, the fascinating thing about this polymer is that unlike many other plastics it has great applications for architecture and building. It is 1% of the weight of glass but it transmits more light, is cheaper to install and is much sturdier and more flexible. Oddly enough for a construction material, it can be used in two different forms: the more conventional sheets of compressed plastic, or it can be made into pneumatic ‘cushions’. The beauty of this cushion form is that it is possible to alter the properties of the material by adjusting the volume of air inside the cushion, in order to let in more light or create more shade. It is also very versatile in that large sheets of ETFE can be sewn together to cover a very large area. Naturally, when in this cushion form it is vulnerable to punctures so it tends to be mostly used in roofing. It also poses extra challenges in terms of acoustics, as the cushions can act like a drum, amplifying the sound of rain.
There are several well-known buildings that have used ETFE in their construction, including the Allianz Arena in Munich (constructed for the 2006 World Cup), the Beijing National Stadium (known as the Bird’s Nest) and the Beijing National Aquatic Centre (known as the Beijing Water Cube), which is the world’s largest structure made of ETFE. As you can see, the effects of using ETFE are very striking and represent an incredible leap forward.
If you’re interested, I got most of my information from here.