MIT Develops Strong, Lightweight Material
Chemical engineers from the Massachusetts Institute of Technology have recently developed a new material using a novel polymerization process.
According to the MIT engineers, the new material is “stronger than steel” and “as light as plastic,” adding that it can be easily manufactured in large quantities.
“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 the senior author of the new study.”
“It has very unusual properties and we’re very excited about that.”
Reported to be a two-dimensional polymer capable of self-assembling into sheets, the induced polymer is a first of its kind. Prior to the research carried out by Strano and his team, polymers were believed to be one-dimensional, spaghetti-like chains called monomers, unable to create 2D sheets.
For many decades, polymer scientists have worked to try and create a two-dimensional, lightweight material. However, a difficult task to say the least, with many of the issues faced during the process revealed themselves when a monomer would rotate up or down, out of the plane of a growing sheet, thus creating a three-dimensional object.
In a new study, Strano and his colleagues were able to overcome what had been chalked up as impossible. Using a new polymerization process, the team was able to generate a 2D sheet, also known as a polyaramide.
To do so, the researchers used melamine as its monomer building blocks, which are reported to contain a ring of carbon and nitrogen atoms. Under proper conditions, the specific monomer can grow in two dimensions, creating a disk shape. After so many disks are created, they are then stacked on top of one another, held together by hydrogen bonds between the layers.
“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 says. “This mechanism happens spontaneously in solution, and after we synthesize the material, we can easily spin-coat thin films that are extraordinarily strong.”
According to the team, because the strong, thin material self-assembles in a solution, it can be made easily in large quantities simply by increasing the quantity of starting materials. To increase the strength of the material, the team also found that the structure could be coated with films of the material, called 2DPA-1.
Following this development, researchers tested the material’s elastic modulus, or how much force it would take to deform it, finding that the polyaramide was between four and six times greater than that of bulletproof glass. In additional testing, the team found that it would take roughly double the amount of force required to break steel to break the polyaramide, despite it being only one-sixth density.
Matthew Tirrell, Dean of the Pritzker School of Molecular Engineering at the University of Chicago, said that the new technique “embodies some very creative chemistry to make these bonded 2D polymers.”
“An important aspect of these new polymers is that they are readily processable in solution, which will facilitate numerous new applications where high strength to weight ratio is important, such as new composite or diffusion barrier materials,” he added.
Another key feature of the developed 2DPA-1 material is that it is impermeable to gases. With the help of ultrathin coatings, the material could prevent gas, water or other substances from getting through it.
“This kind of barrier coating could be used to protect metal in cars and other vehicles, or steel structures,” said Strano.
This research has since been published in the journal Nature and was funded by the Center for Enhanced Nanofluidic Transport an Energy Frontier Research Center sponsored by the U.S. Department of Energy Office of Science and the Army Research Laboratory.
Researchers working on the study have also filed for two patents on the process they used to generate the material. MIT postdoc Yuwen Zeng is the lead author of the study.