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Printed Electronics World
Posted on April 25, 2008 by  & 

Self healing stretchable substrate

IDTechEx conferences and reports on printed electronics have a great deal on smart substrates because they hugely leverage printed technology, making awesome new products possible. These are substrates that change shape under electrical bias, that emit ultrasound, sense various things, act as loudspeakers and microphones and so on. There are electrically unlockable epoxies and substrates that change color under electric bias. However, one of the newest areas of attention has been stretchable substrates because there are now many ways of printing stretchable electronics and electrics to go on them and they are needed for everything from skin patches and implants to toys and merchandising features on packaging.
Hot on the back of these advances, a self healing polymer has been announced. Arkema, a French chemical maker, is planning to develop commercial products based on the new supramolecular chemical technology.
Put To The Test
Researcher demonstrates how the new rubber-like material can be cut, joined together, fixed, and stretched as if the break never happened.
Source: François Tournilhac & Ludwik Leibler, CNRS/ESPCI
A new elastomeric material invented in France can be cut and rejoined at the same spot simply by pressing the broken ends together for a few minutes. This self-healing rubber retains its stretchability even after being severed five or six times, or cut and left alone overnight. A chemical manufacturer is now working to create batches of the material for applications such as sealants. The materials secret is a molecular structure that resembles a plate of spaghetti, says physicist Ludwik Leibler of the National Center for Scientific Research (CNRS) in Paris, who led the team developing the material.
The self-mending occurs because each strand consists of molecules of vegetable fat linked to one other via relatively weak hydrogen bonds. These are the same chemical bonds that give water molecules their cohesiveness. The resulting rubber can stretch to six times its resting length. Nasa is interested in printed electronics because its wide area can confer fault tolerance eg from particle damage. This substrate may help further.
CNRS also researches electroactive polymer foams for ultrasonic transducers and it researches electroactive material that is not a bilayer or sandwich structure but an interpenetrating composite in which the two conducting polymers interact with each other to give new electrical properties. An important advantage of these organic conductive polymer composites is the simplicity of their preparation.
For more see Nature Feb 21 2008 also attend Printed Electronics USA 2008.
Top image: The laboratory setup for creating self-healing rubber from vegetable fat and urea; François Tournilhac & Ludwik Leibler, CNRS/ESPCI.

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Posted on: April 25, 2008

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