Unbreakable glass inspired by seashells

Scientists at McGill University are developing stronger and more resistant glass, inspired by the inner layer of mollusc shells. Instead of shattering on impact, the new material has the resilience of plastic and could be used to enhance cellphone screens in the future, among other applications.

While techniques such as tempering and lamination can help strengthen glass, they are expensive and no longer work once the surface is damaged. “Until now, there have been trade-offs between high strength, toughness and transparency. Our new material is not only three times stronger than normal glass, but also more than five times more resistant to breakage,” says Allen Ehrlicher , associate professor in the Department of Bioengineering at McGill University.

Nature as master of design

Inspired by nature, the scientist created a new composite material of glass and acrylic that imitates mother-of-pearl or mother-of-pearl. “Nature is a master of design. Studying the structure of biological materials and understanding how they work provides inspiration, and sometimes blueprints, for new materials,” explains Ehrlicher.

“Surprisingly, mother of pearl has the stiffness of a stiff material and the durability of a soft material, giving it the best of both worlds,” he explains. “It is made of stiff pieces of chalk-like material that are coated with very elastic soft proteins. This structure produces exceptional strength, making it 3,000 times stronger than the materials it is made of.”

Scientists have taken the architecture of mother-of-pearl and reproduced it with layers of flakes of glass and acrylic, resulting in an exceptionally strong yet opaque material that can be produced easily and inexpensively. They then went further to make the composite optically transparent. “By adjusting the refractive index of the acrylic, we made it blend seamlessly with the glass to create a truly transparent composite,” says lead author Ali Amini, postdoctoral researcher at McGill. In the next steps, they plan to improve it by incorporating smart technology that allows glass to change its properties, such as color, mechanics and conductivity.

Lost invention of soft glass

Soft glass is believed to be a lost invention from the time of the reign of Roman Emperor Tiberius Caesar. According to popular historical accounts by Roman authors Gaius Plinius Secundus and Petronius, the inventor brought a drinking bowl made of this material to the emperor. When the bowl was tested to break it, it only dented instead of shattering.

After the inventor swore he was the only person who knew how to produce the material, Tiberius had the man executed, fearing that the glass would devalue gold and silver because it might be more valuable.

“When I think of the Tiberius story, I’m happy that our material innovation leads to release rather than execution,” says Ehrlicher.