Tuesday, October 30, 2012

Heal thyself

Better living through chemistry, not just a marketing slogan;

...what if we made things from materials that can heal themselves - like a plant or animal heals a wound?
According to experts, the first products with truly self-healing properties may be just around the corner.
....it was a 2001 study by led by Scott White from the University of Illinois at Urbana-Champaign, that really helped to kick-start the field.
The group infused a plastic-like polymer with microscopic capsules containing a liquid healing agent. Cracking open the material caused the capsules to rupture, releasing the healing agent. When the agent made contact with a catalyst embedded in the material, a chemical reaction bonded the two faces of the crack together. The polymer recovered some 75% of its original toughness.
Practical applications would be automobile paints that healed when scratched or cracked concrete; 

Small cracks are a routine outcome of concrete hardening. But over time water and chemicals get inside the fractures and corrode the concrete.
The solution developed at TU Delft could improve the service life of the structure - promising considerable cost savings. Harmless calcite-producing bacteria, along with nutrients, are embedded in the concrete mixture. When water activates the dormant spores, the microbes feed on the nutrients to produce limestone, patching up cracks and small holes.

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