Self Healing PLastic Skin. Polymer, heal thyself.
US researchers have taken a leaf out of nature's book to develop a polymer-based system that can heal itself when it becomes damaged. The material relies on an underlying network of vessels - similar to blood capillaries - that carry a healing agent to areas on the material's surface that become damaged. Unlike previous self-healing systems that relied on capsules of agent buried in the polymer and which became depleted after one use, the new system can respond to damage at the same point many times over.
Nancy Sottos's team at the University of Illinois used a technique called direct-write to create an epoxy-resin base infused with a network of interconnected horizontal and vertical channels 200mu.gifm in diameter. These channels were filled with low-viscosity, monomeric dicyclopentadiene - the healing agent. A solid epoxy resin layer was deposited on top of the vascularised substrate. Grubbs' catalyst, benzylidene-bis(tricyclohexylphosphine)dichlororuthenium, was incorporated into this outer coating.
'After damage occurs at the coating, healing agent wicks from the microchannels into the crack(s) through capillary action,' the researchers report in the journal Nature Materials. 'Once in the crack plane the healing agent interacts with the catalyst particles in the coating to initiate polymerisation, rebonding the crack faces autonomically. After a sufficient time period the cracks are healed and the structural integrity of the coating restored. As cracks reopen under subsequent loading the healing cycle is repeated.'
More... http://www.rsc.org/chemistryworld/News/2007/June/11060701.asp _______________________________________________ NetBehaviour mailing list [email protected] http://www.netbehaviour.org/mailman/listinfo/netbehaviour
