Ningbo / Qingdao, 18 September 2025 — A new computational study reveals that polyethylene furanoate (PEF) — a bio-based polyester — has markedly stronger resistance to hydrogen permeation than commonly used polyamide 6 (PA6) and polyethylene (PE). The work, published in AI & Materials, uses density functional theory (DFT), revised force-field molecular dynamics (MD), Grand Canonical Monte Carlo (GCMC), and nudged elastic band (NEB) calculations to quantify the crystallographic origins of PEF's superior barrier performance, pointing to clear opportunities for safer, more sustainable high-pressure hydrogen storage liners.
Hydrogen storage tanks (Type IV cylinders) rely on polymer liners to prevent leakage at working pressures of 35–70 MPa and operating temperatures from −40 °C to +85 °C. Current petroleum-based liners such as PA6 and HDPE trade off barrier performance, thermal stability and sustainability. PEF — derived from biomass feedstocks and featuring a rigid furan ring — has attracted attention for packaging applications; this study systematically evaluates whether its crystalline form (α-PEF) could be a viable alternative for high-pressure hydrogen applications.
What the researchers did
Led by Zhen Liu, Yaolin Guo and colleagues, the team first used DFT to identify and confirm the thermodynamic stability of the α polymorph of crystalline PEF and to generate benchmarks for force-field parameterization. They then revised the CVFF force field for PEF and validated the MD model against DFT results (lattice parameters, surface energies, NEB barriers). With the validated model they carried out MD and GCMC simulations of H₂ adsorption on representative low-index surfaces, and used NEB calculations (both MD and DFT) to map hydrogen migration pathways and quantify energy barriers for surface entry, escape and bulk diffusion. The study also confirmed the α-phase as the most stable structure under pressure, suggesting potential for a stress-induced transition from other forms.
Key findings
Very high diffusion barriers in PEF. The averaged NEB bulk diffusion barrier for α-PEF is 0.828 eV, approximately 2.9× that of α-PA6 (0.287 eV) and ~26× that of α-PE (0.032 eV).
Strong surface kinetic obstacles. Surface entry, escape barriers for PEF are 0.772 eV and 0.555 eV, respectively — escape is ~3.2 times that of PA6.
Weak physisorption but enhanced at low T. All three crystals show weak H₂ adsorption (<0.1 eV, with PEF's maximum at ~0.09 eV), yet PEF displays relatively stronger adsorption at low temperatures due to an oxygen-rich surface (higher van der Waals and Coulomb contributions).
Crystallographic mechanism identified. PEF's resistance is attributed not only to high bulk density but to quasi-coplanar molecular traps formed by four intrachain oxygen atoms that create additional energy barriers and impede H₂ passage.
Why it matters
These results provide a crystallographic and atomistic explanation for PEF's outstanding hydrogen barrier characteristics and make a compelling case for considering crystalline PEF as a liner material in high-pressure hydrogen storage. Compared with PA6 and PE, crystalline α-PEF combines higher diffusion and escape barriers with strong mechanical and thermal stability, while offering a sustainability advantage as a bio-derived polymer.
Caveats and next steps
The authors caution that this study focuses on crystalline regions — in real semicrystalline materials the amorphous domains dominate gas uptake due to larger free volume. Also, excessive adsorption at cryogenic conditions could cause local accumulation and swelling. The team recommends follow-up experimental validation and extended modeling that incorporates crystal defects, crystal–amorphous interfaces, and realistic microstructures to predict bulk permeability and mechanical responses under service conditions.
Implications
If validated experimentally at device scale, PEF or PEF-based composites could reduce hydrogen permeation losses in Type IV cylinders, improving safety and efficiency for hydrogen transport and storage while advancing the use of more sustainable polymeric materials in energy infrastructure.
The role of AI in future studies
The authors emphasize that artificial intelligence and machine learning will play an increasingly important role in polymer barrier research. By integrating AI with multi-scale simulations and high-throughput screening, researchers could rapidly explore vast chemical and structural design spaces, predict hydrogen permeability with higher efficiency, and identify novel polymer chemistries beyond PEF. Such AI-assisted approaches will complement first-principles and molecular dynamics methods, significantly accelerating the discovery of next-generation hydrogen storage materials.
Article information
Title: Crystallographic insights into the hydrogen barrier mechanism of polyethylene furanoate (PEF) for high-pressure storage applications: comparison with polyamide 6 and polyethylene
Authors: Zhen Liu, Yaolin Guo, Bin Gu, Nianxiang Qiu, Xiaojing Bai, Yifan Li, Zheyu Hu, Muhammad Adnan, Yajie Zhang.
Journal: AI & Materials, 2025(2):0013.
DOI: https://doi.org/10.55092/aimat20250013
