Soon, glass that bends but doesn't break

Scientists are developing a new gen-next glass that bends but does not shatter when dropped.

A new technique developed by researchers makes glass less brittle so that if it is dropped it simply bends and becomes slightly deformed rather than breaking.

Professor Francois Barthelat from the McGill University's Department of Mechanical Engineering and his team took inspiration from the mechanics of natural structures like seashells in order to significantly increase the toughness of glass.

"Mollusk shells are made up of about 95 per cent chalk, which is very brittle in its pure form," said Barthelat.

"But nacre, or mother-of-pearl, which coats the inner shells, is made up of microscopic tablets that are a bit like miniature Lego building blocks, is known to be extremely strong and tough, which is why people have been studying its structure for the past twenty years," said Barthelat.

Previous attempts to recreate the structures of nacre have proved to be challenging, according to Barthelat.

The team studied the internal 'weak' boundaries or edges to be found in natural materials like nacre and then use lasers to engrave networks of 3D micro-cracks in glass slides in order to create similar weak boundaries.

The researchers were able to increase the toughness of glass slides (the kind of glass rectangles that get put under microscopes) 200 times compared to non-engraved slides.

By engraving networks of micro-cracks in configurations of wavy lines in shapes similar to the wavy edges of pieces in a jigsaw puzzle in the surface of borosilicate glass, they were able to stop the cracks from propagating and becoming larger.

The researchers worked with glass slides simply because they were accessible, but Barthelat believes that the process will be very easy to scale up to any size of glass sheet, since people are already engraving logos and patterns on glass panels.

"What we know now is that we can toughen glass, or other materials, by using patterns of micro-cracks to guide larger cracks, and in the process absorb the energy from an impact," said Barthelat.