Plastic just got an upgrade – by utilizing a method thought to be impossible, researchers have created a new material that is as strong as steel but as light as plastic, while still being scalable to be manufactured in large quantities. The team behind it are from MIT and believe the material would be an advanced replacement for electronic devices and phones, building materials, and even the outside coating of cars.
“We don’t usually think of plastics as being something that you could use to support a building, but with this material, you can enable new things,” said Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT and senior author of the study, in a statement.
“It has very unusual properties and we’re very excited about that.”
The material was outlined in a study published in Nature.
The pursuit of a lightweight yet strong material is a continuous effort, but one that requires increasingly advanced synthesis techniques. Two-dimensional materials have come into the spotlight in recent years, with forms of graphene presenting with impressive properties of flexibility and strength that could open new avenues in flexible electronics. However, polymers like plastics that we use on a daily basis would not form 2D sheets – until now.
By using a new polymerization method, the researchers have successfully induced monomers (the short chains of molecules that join together to make a polymer) into creating 2D sheets and remaining in that state. Previously, monomers would rotate and move while the 2D sheet was forming, resulting in the uniform structure being lost and leading scientists to believe creating a 2D polymer is impossible.
In this study, lead author Yuwen Zeng and his team used a compound called melamine as the monomers and an irreversible polycondensation reaction to induce them into forming disks in two dimensions. The disks then layer on top of each other and use hydrogen bonding to remain in place. Once stacked, this new structure creates a material that is incredibly lightweight – around one-sixth the density of steel – but remarkably strong. According to the researchers, the amount of force required to deform the material is twice that of steel, making it pound-for-pound better in almost every metric.
“Instead of making a spaghetti-like molecule, we can make a sheet-like molecular plane, where we get molecules to hook themselves together in two dimensions,” Strano continued.
“This mechanism happens spontaneously in solution, and after we synthesize the material, we can easily spin-coat thin films that are extraordinarily strong.”
Once the precursors are in solution, the polymer self-assembles and forms a film that can coat anything dipped in it. To increase the amount of polymer produced, the researchers can simply increase the amount of ingredients.
“This could allow us to create ultrathin coatings that can completely prevent water or gases from getting through,” Strano said.
“This kind of barrier coating could be used to protect metal in cars and other vehicles, or steel structures.”
Zeng and the team are now continuing investigations into the new process to learn exactly what enables this polymer to form 2D sheets, in the pursuit of more novel materials.