Researchers at MIT and their collaborators have unveiled a groundbreaking 2D polyaramid film with near-perfect molecular impermeability—an ultrathin, solution-processed barrier that rivals graphene yet can be fabricated at room temperature. In our earlier coverage, we explored how this discovery pushes polymer science beyond traditional entangled-chain limitations and opens the door to a new class of hydrogen-bonded, densely stacked molecular sheets.
Now, we sit down with members of the team: Cody Ritt, Michelle Quien, Zitang Wei, Michael Strano and their team behind this breakthrough to take a deeper look at their conceptual leap from conventional polymer films to a true 2D architecture; their synthesis strategy under strictly dry, oxygen-free conditions; and the challenges they faced in validating gas impermeability at the nanoscale. They walk us through the mechanics of their bulge tests, the unexpected microstructural behaviors they observed, and the technological implications—from extending perovskite lifetimes to enabling transformative barrier solutions for energy, packaging, and infrastructure.
You can read more about the discovery in the official MIT News release.
The research paper this interview pertains to can be found here:
Ritt, C. L., Quien, M., Wei, Z., Gress, H., Dronadula, M. T., Altmisdort, K., Nguyen, H. G. T., Zangmeister, C. D., Tu, Y.-M., Garimella, S. S., Amirabadi, S., Gadaloff, M., Hu, W., Aluru, N. R., Ekinci, K. L., Bunch, J. S., & Strano, M. S. (2025). A molecularly impermeable polymer from two-dimensional polyaramids. Nature, 647(8089), 383–389. https://doi.org/10.1038/s41586-025-09674-9
The following interview is presented unedited to preserve the researchers’ original insights into molecular stacking, defect tolerance, long-term stability, and the future of scalable 2D polymer manufacturing.
Acknowledgment from the team: This work was primarily supported as part of the Center for Enhanced Nanofluidic Transport–Phase 2 (CENT2), an Energy frontier Research Center funded by the US Department of Energy, Office of Science, Basic Energy Sciences under grant no. DE-SC0019112. Resonator work performed by H.G. and K.L.E. was supported by the US NSF (grant nos. CMMI-2001403 and CMMI-2337507). K.A. was supported by funding from the Distinguished Summer Research Fellowship (DSRF) and the Undergraduate Research Opportunities Program (UROP) at Boston University. The authors acknowledge the use of the parallel computing resource Lonestar6 provided by the Texas Advanced Computing Center (TACC) at The University of Texas at Austin. Synthetic work was carried out in part under auspices of the Institute for Soldier Nanotechnologies (ISN), and material characterization was carried out in part through the use of MIT.nano’s facilities. Gas adsorption measurements were performed at the National Institute of Standards and Technology (NIST). Certain commercial equipment, instruments or materials are identified in this paper to foster understanding. Such identification does not imply recommendation or endorsement by NIST, nor does it imply that the materials or equipment identified are necessarily the best available for the purpose. We thank J. Qin and S. Eppley for their assistance with deflection measurements for gas-pressurized bulges, D. Lloyd and S. Yang for their help fabricating and preparing the etched substrates used for gas permeation measurements and D. Lundberg for his intellectual contributions.
What inspired the transition from traditional barrier films to a 2D-polyaramid polymer film, and how did your role help shape the conceptual leap toward using hydrogen-bonded molecular sheets?
A lot of traditional barriers are inorganic in nature, such as glasses, metals, or ceramics, with the best of them being inorganic 2D materials like graphene. Despite their advantageous barrier properties, forming these various inorganics into protective coatings often requires high-temperature physical and chemical vapor deposition techniques that are expensive and energy intensive. The processability and formability of conventional polymers is much more favorable, but the dynamic nature of their entangled polymer chains (imagine spaghetti) always results in some amount of open pockets for gas to move through, referred to as “free volume.” Recent work in our group led to the development of a new solution-phase 2D polyaramid that we believed could stack densely like graphene sheets to eliminate these open pockets of space. We thought this in part due to the hydrogen bonds available on the 2D sheets, which leads to favorable interactions between adjacent sheets when stacked.
Could you walk through the key steps in your polymer synthesis and film‐formation (monomer choice, self-assembly, layer stacking), and what parameters (e.g. solvent, monomer concentration, deposition technique) were most critical to achieving the impermeable film?
We synthesized 2DPA-1 via an irreversible polycondensation reaction between two trifunctional monomers—melamine and trimesoyl chloride—under ambient pressure and room temperature in a glovebox. Maintaining strictly moisture- and oxygen-free conditions was essential because trimesoyl chloride is highly hygroscopic. The particle size of 2DPA-1 was tuned by controlling reaction time, which proved critical for forming uniform thin films. For film fabrication, we employed a spin-coating process: first depositing a polystyrene (PS) underlayer, followed by spin-coating the 2DPA-1 dispersion. During deposition, interlayer hydrogen bonding facilitated the assembly of platelets into continuous, smooth films. To achieve impermeability, we dispersed 2DPA-1 in trifluoroacetic acid (TFA), which effectively disrupts hydrogen bonding and delaminates the platelets. This step ensures proper platelet exfoliation for uniform stacking. Optimal film quality required a controlled platelet size and a concentration of 5 mg/mL, yielding a smooth and continuous film approximately 35 nm thick.
Your work reports effectively zero permeability to gases like nitrogen after extended periods. How did your team design and validate the permeability tests (e.g. micro-bubble inflation, long‐term stability), and what were the biggest challenges in proving the barrier performance?
With these nanometer-thin films, researchers have had to be creative with how to characterize them because it isn’t always straightforward to make large, macro-scale samples. The bulge test we used for this study originated from the blister test, which uses the same premise of a film suspended over a well so that researchers can measure their mechanical properties (such as the elastic modulus or yield strength). The blister test then inspired a series of studies on the molecular impermeability of graphene to various gases, which is what we used as the basis for our experiments.
Some of the biggest challenges were in identifying and isolating the effect of each factor at play. For example, one of the pivotal studies on graphene’s molecular impermeability identifies that gases can escape through the silicon wafer instead of the film. In our samples, we identified that the trapping of gas is likely affected by the way in which the film adheres to the silicon wafer, complicating how we make the samples and how we analyze the data. We also found there to be fluctuations in the heights of our bulges that complicated our analysis, and serendipitously we were able to correlate with the movement of gas molecules trapped inside the bulges.
How does the microstructure of your 2D polymer film; stacked disks with hydrogen bonds and near-void-free packing, compare with more conventional polymer films in terms of gas‐transport pathways and defect tolerance?
The microstructure of this material is entirely different from conventional polymer films. In conventional polymer films, you generally have two phases: a “crystallite” and “amorphous” phase. The crystallite phase is a region in the polymer where the polymer chains stack tightly next to one another, leaving no room for gas transport. By contrast, the amorphous phase is where the polymer chains are randomly entangled amongst each other, leading randomly dispersed open pockets for gas transport. The 2D nature of our polyaramid films allows them to stack tightly next to each other to eliminate these open spaces, behaving like a crystallite.
Given that you’ve demonstrated a 60-nanometre coating extends perovskite lifetime by weeks, how do you envision scaling this technology for real‐world applications (solar cells, packaging, infrastructure), and what manufacturing or integration hurdles remain?
Our work demonstrates that ultrathin 2DPA-1 coatings can significantly enhance the stability of air- and moisture-sensitive semiconductors, offering a transformative approach for solar cell encapsulation. Unlike conventional polymeric encapsulants that require micrometer- to millimeter-scale thickness, a 60 nm 2DPA-1 layer provides outstanding protection, enabling more cost-effective and sustainable solutions. The simplicity of deposition methods—such as spin coating, blade coating, or drop casting—makes large-scale implementation feasible and compatible with existing fabrication workflows. However, key challenges remain, including reliance on acidic solvents like TFA and ensuring compatibility with industrial processing standards. We are actively developing alternative fabrication routes and integration strategies to overcome these hurdles and meet scalability requirements for solar cells, packaging, and other infrastructure applications.
From your perspective, what are the durability and ageing concerns for this film in practical use, such as UV exposure, abrasion, thermal cycling and what testing or modifications are underway to address these?
One of the biggest concerns for this class of materials, polyaramids, is how susceptible they are to water and humidity; in fact, this is a known concern with polymers like Kevlar. When you look at the molecular structure, you’ll notice that there’s a lot of opportunities for water to hydrogen bond to our material, which then could interrupt how individual molecules stack together and degrade the mechanical and gas barrier properties. Fortunately, we have noted a distinct lack of property degradation, from 2DPA-1 powders submerged in water for years to films that demonstrate nitrogen impermeability for years.
Regarding other properties, we know that our films are highly chemical stable, only dissolving when exposed to trifluoroacetic acid and dimethyl sulfoxide. We also know from TGA (thermogravimetric analysis) that 2DPA-1 powders will begin to degrade around 250C. We’re invested in future studies to better understand more facets of the performance of 2DPA-1 films; in particular, we have ongoing studies into how to control their thermal stability.
Looking ahead, what next research directions do you anticipate? Are you exploring thicker coatings, alternate monomers, even lower cost processing, or new applications in wearable electronics or food/medicinal packaging?
That’s the exciting thing about this material. There are so many different avenues to explore, all of which we are interested in pursuing. I think our first and foremost interest is to investigate the extent of the molecular impermeability with these films. Can they be leveraged to achieve large-scale hydrogen barriers? That could be a game-changer for a renewables driven economy, so we’re looking into a number of different routes to try and make that possible.
Hassan graduated with a Master’s degree in Chemical Engineering from the University of Chester (UK). He currently works as a design engineering consultant for one of the largest engineering firms in the world along with being an associate member of the Institute of Chemical Engineers (IChemE).
