Researchers at the University of Illinois said their new material makes possible a more practical way to repair composites used in structural applications ranging from airplane fuselages to wind-farm propeller blades.

The self-healing system incorporates chlorobenzene microcapsules as small as 150 microns in diameter as an active solvent. The expensive, ruthenium-based Grubbs' catalyst, which was required in the researchers' first approach, is no longer needed.

"By removing the catalyst from our material system, we now have a simpler and more economical alternative for strength recovery after crack damage has occurred," said Professor Jeffrey Moore. "Self-healing of epoxy materials with encapsulated solvents can prevent further crack propagation, while recovering most of the material's mechanical integrity."

The new chemistry is described in a paper accepted for publication in the journal Macromolecules and posted on the journal's Web site.