Optical micrograph of MIT's new polymer filmMIT
MIT researchers have created a polymer film so impermeable that even nitrogen molecules can’t pass through it, potentially revolutionizing corrosion protection for solar cells, food packaging, and infrastructure.
The lightweight material, only nanometers thick, blocks gases more effectively than any polymer ever made and rivals graphene’s molecular impermeability.
The new polymer can be produced in bulk and applied easily. The discovery could enable large-scale use of impermeable coatings once limited by graphene’s scalability issues.
The polymer, known as 2DPA-1, is a two-dimensional polyaramid that self-assembles into tightly packed molecular sheets using hydrogen bonds.
MIT’s Carbon P. Dubbs Professor of Chemical Engineering Michael Strano and Scott Bunch of Boston University led the research, along with former MIT postdoc Cody Ritt, graduate student Michelle Quien, and research scientist Zitang Wei.
“Our polymer is quite unusual,” says Strano. “It’s obviously produced from a solution-phase polymerization reaction, but the product behaves like graphene, which is gas-impermeable because it’s a perfect crystal. However, when you examine this material, one would never confuse it with a perfect crystal.”
Unlike typical polymers that allow gases to seep through gaps between tangled molecular chains, 2DPA-1’s structure leaves no space between its disk-like layers.
That compact arrangement prevents even the smallest gas molecules from slipping through.
Strano’s lab first developed the material in 2022, showing that it was stronger than steel yet six times lighter.
When they made “bubbles” from the polymer, the trapped gas never escaped. “Bubbles that they made in 2021 are still inflated,” Ritt recalls. “The behavior of the bubbles didn’t follow what you’d expect for a typical, permeable polymer.”
After a long series of controlled tests, Strano’s team confirmed that 2DPA-1 is “molecularly impermeable to nitrogen.”
The polymer also resisted helium, argon, oxygen, methane, and sulfur hexafluoride, performing at least 10,000 times better than other polymers.
Northwestern University’s George Schatz called the results “remarkable,” saying the polyaramids are “orders of magnitude less permeable to most gases under conditions with industrial relevance.”
Protecting solar cells and structures
The team also demonstrated the film’s potential as a protective coating.
A 60-nanometer layer extended the lifespan of a perovskite crystal, a promising solar-cell material, from days to three weeks. Thicker coatings could offer even longer protection.
“Using an impermeable coating such as this one, you could protect infrastructure such as bridges, buildings, rail lines, basically anything outside exposed to the elements,” says Strano.
“Automotive vehicles, aircraft and ocean vessels could also benefit. The shelf life of food and medications can also be extended using such materials.”
While graphene offers similar impermeability, it’s notoriously hard to scale.
“We can only make crystal graphene in very small patches,” Strano says. “People have tried to paint it on, but graphene does not stick to itself but slides when sheared.”
2DPA-1, by contrast, adheres easily because of hydrogen bonding, allowing for larger, more stable coatings.
Tiny resonators and future uses
The researchers also used 2DPA-1 to build a nanoscale resonator, a microscopic vibrating drum that could shrink communication devices.
“In this paper, we made the first polymer 2D resonator, which you can do with our material because it’s impermeable and quite strong, like graphene,” Strano says.
Such resonators could lead to smaller, energy-efficient phones and serve as sensitive molecular sensors.
The study is published in the journal Nature.
