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Big cracks in polymers can have fatal consequences, as the doomed 1986 flight
of NASA’s Challenger shuttle testified. Now scientists have developed an epoxy
that can heal tiny cracks before they can do any damage. Scott White of the
University of Illinois at Urbana-Champaign made the self-healing polymer by
mixing a catalyst and tiny plastic capsules containing a chemical called
dicyclopentadiene (DCPD). When a crack appears in the polymer, it breaks open
the capsules which flood the crack with DCPD. When it meets the catalyst, the
DCPD polymerises into a tough plastic that heals the crack (Nature, vol
409, p 794).