Researchers at the US-based Massachusetts Institute of Technology (MIT, Cambridge, Massachusetts; www.mit.edu) say they have created a two-dimensional polymer with significant strength and barrier properties.

The material, called 2DPA-1, “self-assembles into sheets, unlike all other polymers, which form one-dimensional, spaghetti-like chains,” the university said. “Until now, scientists had believed it was impossible to induce polymers to form 2D sheets.”

According to Professor Michael Strano, “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. This mechanism happens spontaneously in solution, and after we synthesise the material, we can easily spin-coat thin films that are extraordinarily strong.”

Researchers told Plasteurope.com that “In the lab, we produce it by adding trimesoyl chloride and melamine to a solution.” The 2D structure forms in the solution, and it is isolated into a powder, which can be dissolved and turned into films by spin-coating.

The developers noted that the “PA” in the material name stands for polyamide. “Our current experiments so far suggest it is not a thermoset or thermoplastic.”

The university said it is used to make two-dimensional sheets of what it calls “polyaramide”.

The material has some similarities with Kevlar, researchers told PIE. “Both polymers form the same type of bonds (amide bonds) and their monomers both have aromatic cores.” The main difference is that Kevlar uses bifunctional monomers and 2DPA-1 is made of trifunctional monomers.

The university declined to discuss larger-scale production or partners who may be considering making the material or testing it for various applications. MIT noted that its own research into possible uses for the discovery is ongoing.

The material’s elastic modulus is said to be between four and six times greater than that of bulletproof glass, and yield strength was cited at twice that of steel at one-sixth the density.

Production of the material appears to be a major breakthrough. MIT cited “decades of work in this field” that suggested it was impossible to create lightweight and strong 2D sheets. “One reason is if just one monomer rotates up or down, out of the plane of the growing sheet, the material will begin expanding in 3D, and the sheet-like structure will be lost.”

The university reported that the material is impermeable to gases. “While other polymers are made from coiled chains with gaps that allow gases to seep through, the new material is made from monomers that lock together like Legos, and molecules cannot get between them.”

Strano said, “This could allow us to create ultrathin coatings that can completely prevent water or gases from getting through. This kind of barrier coating could be used to protect metal in cars and other vehicles, or steel structures.”