Chainmail-Inspired Success Could Redefine the Future of Armor

Imagine armor as light as fabric but stronger than steel, built from materials that link together like a chain of cells. Scientists may have just taken the first step to make this possible.

A team of researchers led by Northwestern University scientists has developed what could be two-dimensional (2D) mechanical links, similar to chainmail links. This article, published in January 16 learning published in the magazine Scienceit is exceptionally flexible and strong, with promising applications in products such as light weapons and ballistic fabrics.

The researchers created the material at the nanoscale, meaning that individual components can be measured in nanometers. It is technically a polymer: a substance made up of large molecules, which in turn are made up of smaller units called monomers. Examples of polymers are proteins, cellulose, and nucleic acids.

The 2D mechanically interlocked material is a polymer that uses mechanical bonds-physical bonds, unlike, for example, covalent bonds, which usually form polymers and involve electron sharing. The material contains 100 trillion mechanical elements per 0.16 inch (1 square centimeter), which is the smallest density of mechanical elements ever created, according to researchers.

“We created a new polymer structure,” said study co-author William Dichtel of Northwestern University. words. It’s the same with a chain because it can’t break easily because every fastener has the freedom to move. When you pull it, it can lose power in a number of ways. And if you want to rip, you have to rip in a lot of different places. We continue to research its content and will likely be studying it for years. “

A major challenge in the design of mechanically cross-linked molecules is figuring out how to direct the polymers to form mechanical bonds. Madison Bardot of Northwestern University, who led the research, is credited with coming up with a new way to achieve this. The team put the x-shaped monomers into a crystalline form (special arrangement) and reacted with another molecule. This created a mechanical bond within the crystal. The final product is a 2D layer of closed polymer sheets made of these bonds between X-shaped monomers, which the researchers filled with more X-shaped monomers.

“It was a high-risk, high-reward idea where we had to question what we thought about what kinds of activities were possible in molecular crystals,” Dichtel said. The composition is very strong, yet flexible and easy to use, because single sheets of closed molecules separate from each other when the polymer dissolves in the solvent.

“Once the polymer is made, there is not much that holds the building together,” he added. “So, when we put it in a solvent, the crystal melts, but each 2D layer is aligned. We can change these sheets.”

While previous researchers have created very small amounts of mechanically bound polymers that would have been difficult to mass-produce, the team’s new approach is surprisingly feasible. They made more than one kilogram (0.5 kg), and said they could make more.

Even a small part of the new polymer structure, however, can fix other things. The researchers created a material made of 97.5% Ultem fiber (the strongest material in the same family as Kevlar) and 2.5% 2D polymer, and determined that the mixture made the original much stronger.

“We have a lot to analyze, but we can say that it contributes to the durability of these composite materials,” Dichtel said. “Almost every place we measured is unique in some way.”

These powerful and flexible tools may be the tools the future has been waiting for.