Molecular weaving itself is a young discipline. Instead of tying polymer chains together with covalent bonds at every crossing, woven networks rely on mechanical interlocking: molecular threads pass over and under one another the way warp and weft strands do in a loom, but without covalent links at the crossings. This gives the material a bottom-up route to topological control, because properties such as flexibility, porosity, and stress distribution are dictated not only by the chemistry of the threads but by their geometry of entanglement. Landmark achievements over the past decade, including woven covalent organic frameworks and layered two-dimensional molecularly woven fabrics, proved that such structures could be made and crystallized. Yet every one of these materials shared a common constraint: they contained exactly one type of woven motif, repeated uniformly across the network. The fabric of everyday life, by contrast, achieves much of its sophistication through hierarchical layering, with threads crossing threads at several organizational levels simultaneously.

The Zhejiang-led team closed that gap through careful regulation of two design variables: the size of the molecular building blocks and the solvent environment in which the threads assemble. By tuning monomer dimensions, the researchers controlled how many strands could pass through a given region of the forming network, while solvent templating guided the strands into overlapping registration states during crystallization. The outcome is a family of materials labeled woven polymer networks, non-woven polymer networks, and, crucially, multilevel woven polymer networks such as MWPN-1 and MWPN-2, in which several woven topologies coexist in one ordered two-dimensional sheet. The authors describe the result as analogous to the structure of macroscale complex fabrics, in which threads weave through threads at more than one level of organization.

Proving that a structure this intricate genuinely exists required an unusually broad battery of characterization techniques. Single-crystal X-ray diffraction, the gold standard for establishing atomic connectivity in crystalline materials, provided unambiguous evidence of the multilevel woven architecture, and the crystallographic data have been deposited with the Cambridge Crystallographic Data Centre. Because these polymer sheets are extremely sensitive to electron beams, the team also deployed integrated low-dose and cryogenic electron microscopy imaging, adapting methods that have recently transformed the study of beam-sensitive frameworks such as metal-organic structures. Together, these independent imaging approaches confirmed the presence of the multilevel woven structure, ruling out the possibility that the exotic topology was an artifact of one analytical method.

With the structure established, the researchers turned to the question that motivates much of molecular weaving: does the topology change how the material behaves under stress? The answer, obtained through in situ pressure-dependent Raman spectroscopy combined with theoretical calculations, is emphatically yes. When the multilevel woven network is compressed, mechanical stress is distributed through a hierarchical mechanism that has no analogue in the single-level woven counterpart material. In a single-level weave, load transfer follows one set of crossing points; in the multilevel architecture, stress cascades through successive layers of interlocking strands, allowing the network to deform and redistribute force in a fundamentally different way. The team also measured nanoscale mechanical properties, including modulus distributions and force curves, showing quantitatively how the woven hierarchy alters the material’s elastic response.

This hierarchical stress regulation is more than a curiosity of mechanics. It demonstrates the central claim of the paper: that moving from single-level to multilevel woven topologies is not merely a structural upgrade but introduces properties and functions that lie beyond the reach of single-level systems. In conventional polymer design, chemists tune properties by changing monomer chemistry. Here, the same chemical building blocks yield materials with different mechanical signatures purely by changing the topological arrangement of the threads. That decoupling of function from composition is precisely what makes woven materials attractive as a design platform, and the new work shows that the platform is far richer than previously appreciated.

The practical payoff emerged in an area of intense industrial interest: hydrocarbon separation. Toluene and methylcyclohexane are chemically similar molecules, differing in that one is aromatic and the other is a saturated ring, yet separating them is a significant challenge in the petrochemical industry. The pair also matters for energy storage, because toluene and related molecules serve as liquid organic hydrogen carriers, media in which hydrogen can be stored and transported chemically. Efficient, low-energy separation of these species is therefore a bottleneck in emerging hydrogen economies. Breakthrough experiments simulating industrial separation processes showed that the multilevel woven material substantially outperforms expectations, thanks to synergistic channels generated by its multilevel woven topology. The hierarchical network creates a pore environment that discriminates between toluene and methylcyclohexane with a precision unavailable in the single-level analogue.

The origin of that selectivity is instructive. In the multilevel fabric, channels formed by one level of weaving intersect and interpenetrate channels formed by another, producing a combined pore landscape that neither topology would generate alone. Adsorption measurements on the material showed how guests interact with these channels, and comparisons among the woven, non-woven, and multilevel members of the family allowed the team to isolate the topological contribution to separation performance. In effect, the study provides a rare direct demonstration that mechanical interlocking geometry, not just pore size or surface chemistry, can be engineered to solve a real separation problem.

The synthetic chemistry underlying the achievement draws on the team’s prior expertise with dative boron-nitrogen bonds and with purely organic free-standing two-dimensional woven polymer networks, which the group reported in 2024. Those earlier single-level crystals established that robust, crystalline, all-organic woven sheets could be grown and handled. The new work extends that platform into the hierarchical regime, and the eleven distinct crystal structures deposited alongside the paper, spanning the woven, non-woven, and multilevel series, suggest a modular chemistry in which monomer size and solvent choice can be varied systematically to access different topological outcomes. Such a library is exactly what the field needs to move from proof-of-concept demonstrations to rational materials design.

The implications reach well beyond one material. Multilevel weaving offers a general strategy for building topological hierarchy into soft crystalline matter, with potential applications in adaptive membranes, mechanoresponsive materials, and selective adsorbents for energy-relevant separations. It also raises new questions that the community is only beginning to formulate: How many levels of weaving can be incorporated into a single network? Can topologies be switched after synthesis, in the way that some woven frameworks show dynamic guest-responsive behavior? And can the hierarchical stress-distribution mechanisms observed here be harnessed in three-dimensional architectures or in devices? What is already clear is that molecular weaving has crossed a threshold. Just as the leap from a plain cloth to a layered technical fabric transformed what textiles can do, the leap from single-level to multilevel molecular weaving transforms what woven matter can achieve, giving chemists a fabric-like degree of architectural control over materials measured in nanometers rather than millimeters.

Subject of Research: Synthesis of a two-dimensional multilevel woven polymer network with multiple woven topologies for stress regulation and molecular separation

Article Title: Multilevel molecular weaving

Article References: Chen, L., Guo, Z., Xiao, D., Liu, Y., Shan, T., Yang, X., Zhang, Z., Hu, D., Miao, X., Liu, S., Zeng, Q., Xiao, X., Wang, M., Zhu, Y., Li, G., & Huang, F. (2026). Multilevel molecular weaving. Nature Materials. https://doi.org/10.1038/s41563-026-02754-9

Image Credits: AI Generated

DOI: 10.1038/s41563-026-02754-9

Keywords: molecular weaving, two-dimensional polymers, supramolecular chemistry, self-assembly, topology, porous materials, mechanical properties, crystallography, cryo-electron microscopy, Raman spectroscopy, hydrocarbon separation, liquid organic hydrogen carriers

The work comes from SUPREN, a research group at EHU that is leading a large-scale European project known as UnLOHCked, focused on the social, environmental and economic assessment of large-scale green hydrogen supply chains in Europe. Victoria Laura Barrio, full professor at EHU and lead researcher of the project, explains that one of the central challenges facing these supply chains is deceptively simple: how to move and store the gas itself. Hydrogen contains a vast amount of energy per kilogram, but as an ultra-light gas it occupies an enormous volume, which makes transporting and storing it both technically awkward and expensive. Solving that logistics problem is widely seen as a prerequisite for building an international hydrogen market.

One of the most promising answers is a family of materials known as liquid organic hydrogen carriers, or LOHCs. These are organic liquids that behave much like conventional oils, into which hydrogen is incorporated through a straightforward chemical reaction. Because the hydrogen is chemically bound within a pumpable liquid, it can be stored and transported using existing oil and gas infrastructure, a fact that could dramatically lower the barriers to international trade. At the destination, the hydrogen is released from the carrier through a reverse process, and the carrier liquid can be returned for reuse. The researchers emphasise the technology’s considerable potential and foresee it playing a key role in the global green hydrogen trade in the near future.

The strategic logic of LOHC-based trade is already shaping national planning. Several countries are developing future strategies for the production, export, import and consumption of hydrogen, and Barrio notes that it would make particular sense to bind hydrogen to the liquid carrier in southern Europe or Africa, where solar energy is highly competitive, or in regions with strong wind energy potential. The hydrogen could then be shipped easily in the form of LOHC, riding on infrastructure originally built for fossil fuels. In this vision, sun-belt and wind-belt exporters become the energy suppliers of a decarbonising world, while industrial importers in northern Europe and East Asia plug into those flows.

To test whether such flows can truly be sustainable, EHU researcher Irene Rey carried out a detailed sustainability assessment of these international supply chains, now published in the Chemical Engineering Journal. The team performed a life cycle assessment of every stage involved in generating green hydrogen, hydrogenating it into the carrier liquid, transporting it by sea to the end consumer, releasing it at its destination and returning the carrier liquid, while excluding the final use and consumption of the hydrogen itself. The analysis contemplated different configurations of producing countries with high renewable potential, including Namibia, Saudi Arabia, Norway and Spain, and consumer countries such as Germany, the Netherlands, Japan and Italy, alongside maritime transport routes and different types of land-based distribution.

The study’s principal innovation lies in what it added to the conventional toolkit. Life cycle assessment and techno-economic analysis are standard instruments for evaluating energy systems, but the researchers also incorporated a social risk analysis of the supply chains, an aspect that has been little studied until now. Because hydrogen production would be located in countries with markedly different social, economic, political and institutional conditions, the production stage shows a high variation in potential social risks. Labour standards, governance quality, human rights conditions and community impacts all vary enormously between candidate exporter nations, meaning that two hydrogen molecules with identical carbon footprints can carry very different social burdens depending on where and how they were made.

The technical results point clearly to where improvement efforts should be concentrated. The researchers found that further work is needed to improve the efficiency of green hydrogen production and of the release of hydrogen from the carrier, since both stages involve high energy consumption and are the most critical links in the supply chain. Electrolysis powered by renewable electricity and the dehydrogenation step at the point of import together determine much of the overall energy penalty, emissions profile and cost of delivered hydrogen. Gains in these two stages would ripple through the entire system, improving every sustainability dimension simultaneously.

Yet the study’s most sobering conclusion is that no configuration emerges as a winner on all fronts. According to Rey, the results show that there is no perfect scenario delivering benefits across the social, environmental and economic dimensions at once. Instead, she argues, a balance should be achieved across the entire supply chain, with priority not given only to economic aspects. Routes that minimise delivered cost may concentrate social risk in vulnerable producer regions, while configurations that maximise environmental performance may struggle to compete commercially. Designing the future trade will therefore require explicit trade-off analysis and policy frameworks that internalise social and environmental performance alongside price.

The stakes of getting this right are considerable. Hydrogen could account for up to 14 percent of global final energy consumption by 2050, with an ever-increasing share traded internationally as new value chains emerge, a shift likely to reconfigure global energy trade much as oil did in the twentieth century. Regions with abundant renewable resources, such as Africa, Latin America, the Middle East and Oceania, are increasingly viewed as potential exporters, while Europe, Japan and South Korea are expected to become key importers. Rey cautions that designers of green hydrogen corridors must do more than simply reduce carbon emissions and production costs; they must also consider the geopolitical and social implications of the flows they create.

Her question cuts to the heart of the energy transition’s equity dilemma: how can a future hydrogen trade be developed without reproducing the resource extraction dynamics in which the Global South supplies raw energy for the benefit of the technological and economic development of the Global North? The EHU study, conducted as part of Rey’s doctoral thesis at the Chemical and Environmental Engineering Department of the Bilbao School of Engineering under the direction of Ion Agirre and Professor Barrio, and carried out in collaboration with the Polytechnic University of Milan, offers a springboard for answering it. By demonstrating that social risk can be quantified and integrated into supply chain design alongside environmental and economic metrics, it provides policymakers and industry with a practical framework for building a hydrogen trade that is not only clean and competitive, but also just.

Subject of Research: Sustainability assessment of international LOHC-based green hydrogen supply chains

Article Title: The design of the future global trade in green hydrogen should also consider social and environmental aspects

Article References: The design of the future global trade in green hydrogen should also consider social and environmental aspects. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: green hydrogen, liquid organic hydrogen carriers, LOHC, hydrogen supply chains, life cycle assessment, social risk analysis, energy transition, renewable energy, global hydrogen trade, sustainability, electrolysis, energy policy

One of the significant innovations introduced with the SPAES membrane is its ability to drastically reduce toluene permeability. This is particularly critical, as liquid organic hydrogen carriers (LOHCs) such as toluene are increasingly recognized as viable mediums for safely storing and transporting hydrogen. Conventional methods of hydrogen storage, which involve high pressures of over 100 bar or extreme low temperatures of -252.9 °C, pose several handling and safety challenges. In contrast, LOHCs provide a much more manageable alternative since they can be stored and transported under milder conditions.

However, the use of LOHCs presents challenges, particularly regarding the unwanted crossover of toluene molecules through the membrane in electrochemical hydrogenation systems. This crossover significantly undermines operational efficiency. Moreover, it has the potential to contaminate the oxygen evolution reaction (OER) catalyst present on the anode side, which can lead to detrimental impacts on the overall system performance. Addressing this issue was crucial for the success of the new membrane technology.

In their research, the team at KRICT developed the new SPAES membrane with particularly narrow hydrophilic domains, measuring approximately 2.1 nm in width. These channels serve as dedicated proton pathways within the membrane and are designed to reduce toluene permeability significantly. The innovative structure of the SPAES membrane facilitates the exclusion of toluene while promoting efficient proton transport, which is critical for achieving high performance in electrochemical processes. The outcome is a remarkable reduction in toluene crossover, decreased by more than 60% when compared to Nafion.

Moreover, the introduction of the SPAES membrane led to a considerable increase in the Faradaic efficiency of the hydrogenation process, raising it from 68.4% with Nafion to an impressive 72.8% with the new membrane. This enhanced efficiency represents a major leap forward in the functionality of PEMs, setting the stage for improved performance of hydrogen storage systems. Additionally, during long-term operational tests lasting 48 hours, the voltage degradation rate was also reduced significantly by 40%, demonstrating not only the enhanced performance but also the robust stability of the SPAES membrane over extended use.

The potential applications for this revolutionary technology extend far beyond academic curiosity, as the researchers envision its integration into practical setups for hydrogen storage and energy production. They foresee standalone, high-efficiency electrochemical hydrogen storage systems reaching commercialization by 2030. This advancement could lead to substantial developments in eco-friendly energy solutions, particularly relevant for hydrogen fuel cell vehicles and hydrogen power generation initiatives.

KRICT’s President, Youngkook Lee, expressed optimism regarding the widespread applicability of the SPAES membrane technology within the realm of sustainable energy systems. He noted that this innovation could significantly contribute to the hydrogen economy and help overcome existing performance bottlenecks associated with membrane technologies currently in use for electrochemical hydrogen storage applications.

The collaborative research led by Dr. So and Professor Lee also aligns with KRICT’s dedication to advancing chemical technologies for broader societal benefits. As an institute founded in 1976, KRICT has been at the forefront of research in various scientific fields, including chemistry, material science, and environmental science. Their ongoing commitment emphasizes the importance of developing solutions that address critical global challenges related to energy production and sustainability, an imperative that continues to gain urgency in today’s world.

The findings from this research were published in the highly-regarded Journal of Materials Chemistry A, which boasts an impressive impact factor of 10.7. The publication marks a significant milestone in the academic discourse surrounding membrane technology and highlights the promising future of electrochemical hydrogen storage systems fueled by innovative research and development.

This critical work in membrane technology represents a strategic alignment of fundamental research and applied science, demonstrating that advancements in materials science can lead to practical solutions that bolster the transition to a hydrogen-powered future. It is a clear testament to the potential of scientific research to drive progress in energy technologies, harboring hope for sustainable energy solutions that will play a crucial role in achieving global climate goals.

Through continuous research and collaboration, such innovations pave the way for not just technical progress but also for broader systemic changes in how society approaches energy use and sustainability. Ultimately, the development of more efficient, cost-effective, and stable hydrogen storage systems is poised to catalyze the next phase of the energy transition, moving toward a cleaner, more efficient, and environmentally conscious future.

Subject of Research: Development of a new proton exchange membrane (PEM) for electrochemical hydrogen storage systems
Article Title: An efficient toluene barrier membrane for high-performance direct toluene hydrogenation via an electrochemical process
News Publication Date: February 14, 2025
Web References: http://dx.doi.org/10.1039/D4TA06773H
References: Journal of Materials Chemistry A (IF 10.7)
Image Credits: Korea Research Institute of Chemical Technology (KRICT)

Keywords

Proton exchange membranes, electrochemical hydrogen storage, sulfonated poly(arylene ether sulfone), SPAES membrane, liquid organic hydrogen carriers, Faradaic efficiency, hydrogen economy, KRICT, sustainable energy solutions.