- Glass and acrylic composite material provides a durability that is more like plastic
- It mimics mother of pearl – the inner iridescent layer of molluscan shells
- It is three times stronger and five times more fracture resistant than normal glass
A new type of glass has been created that is five times more resistant to fracture than standard glass – and it could end up with cracked phone screens eventually.
The glass and acrylic composite material, which ‘offers a combination of strength, hardness and transparency’, was designed by researchers from McGill University in Montreal, Canada.
The strong and tough glass is inspired by the inner layer of mollusk shells, called nacre, also known as mother of pearl, which resembles a wall of interwoven Lego bricks on a microscopic scale.
Although it is glass, the new material has a ductility that is like plastic and does not break upon impact, the researchers report.
If mass-produced and brought to market, it could be used to break high-end smartphones to the ground with a small drop.
(a) Glass composite before and after changes in refractive index to make it transparent. The material circle on the right highlights its transparency and suitability for smartphone screens; (b) the microscopic structure of the material; (c) View of the nacreous layer in the red abalone shell; (d) microscopic structure of nacre
What is nacre?
Nacre, also known as mother of pearl, is the inner iridescent layer of molluscan shells.
Nacre is crystallized calcium carbonate that ‘blisters’ around a foreign contaminant inside an oyster shell to protect its body.
The nacre surrounds an object and forms a pearl.
But this process can take years – the longer it is allowed to continue, the larger the pearl becomes and more layers of nacre are added.
It is highly flexible, allowing the shell to resist impacts without fracturing.
The shells of mollusks are made up of about 95 percent chalk, which is very brittle in its pure form.
But the nacre, which coats the inner shell, is made of microscopic bullets that are like miniature Lego building blocks, making it extremely strong and tough. It is highly flexible, allowing the shell to resist impacts without fracturing.
“Amazingly, nacre has the hardness of a hard material and the durability of a soft material, giving it the best of both worlds,” said Alan Erlicher, an associate professor in the Department of Bioengineering at McGill University.
‘It is made of hard pieces of a chalk-like substance that are layered with soft proteins that are highly elastic.
‘This structure produces exceptional strength, which makes it 3,000 times harder than the materials that make it up.
‘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.’
While techniques such as tempering and laminating can help strengthen the standard glass on today’s phones, they are expensive and no longer work once the surface is damaged.
‘Until now there were trade-offs between high power, brutality and transparency,’ Professor Erlicher said.
‘Our new material is not only three times stronger than normal glass, but also five times more fracture resistant.
Scientists at McGill University have developed a strong and tough glass inspired by the inner layer of mollusk shells. Instead of shattering upon impact, the new material has the flexibility of plastic and could be used in the future to improve cell phone screens, among other applications.
(a) The McGill University team’s microstructure of the glass composite and (b) the microstructure of the nacre. Note the brick wall-like arrangement of the nacre surface
The nacre is composed of hexagonal or square platelets of aragonite (a form of calcium carbonate), arranged like a brick wall.
The scientists took the architecture of nacre and replicated it with flakes of glass and layers of acrylic, producing an ‘extraordinarily strong’ opaque material that can be produced easily and cheaply.
They then went a step further to make the composite transparent by changing the refractive index of the acrylic material.
The refractive index refers to how the speed of light varies between different mediums.
Lead author Ali Amini, McGill’s postdoctoral researcher, said: ‘By tuning the refractive index of acrylic, we have mixed it with glass to create a truly transparent composite.
The next step for the team is to improve unbreakable glass by incorporating smart technology that allows the glass to change its properties, such as colour, mechanics and conductivity.
Nacre, also known as mother of pearl, is the beautiful inner iridescent layer of molluscan shells
The team wrote in their paper, ‘The glasses have many applications because of their exceptional transparency and hardness. magazine Science.
‘NSOverwear, poor fracture, impact resistance, and mechanical reliability limit their range of applications.
‘The fabrication method is robust and scalable, and the compound could prove to be a glass substitute in diverse applications’.’
McGill University has been working on more durable glass for years – in 2019, a team from another lab published a letter On glass inspired by nacre.
They pulsed ultraviolet laser beams to engrave hexagonal patterns on borosilicate glass sheets to mimic Nacre’s design.
“Current advances are numerous – our composite is optically transparent like regular glass, whereas previously it had checkerboard patterns,” Professor Erlicher told MailOnline.
‘Our composites are prepared in bulk by centrifugation rather than serial etching with a high-powered laser – this means ours can be made in large quantities and cheaply.’
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