The work, led by Associate Professor Daisuke Aoki of the Graduate School of Engineering at Chiba University, was published in Volume 16 of the journal Scientific Reports on August 18, 2026. The research team included Mr. Shunsuke Fujimata and Dr. Tatsuo Taniguchi from Chiba University’s Graduate School of Science and Engineering, Dr. Takehiro Kamiya from the Graduate School of Agricultural and Life Sciences at The University of Tokyo, and Dr. Mizuhiko Nishida from the Graduate School of Agricultural Science at Tohoku University. Together, they engineered a bio-based plastic system built around a remarkable sugar-derived molecule, and they demonstrated that the entire material — polymer and additive alike — can be chemically converted into compounds that support plant growth.

The star of the chemistry is isosorbide, abbreviated ISB, a rigid bicyclic diol synthesized from glucose. Isosorbide is derived from biomass rather than petroleum, which already gives the material a sustainability credential that conventional plastics lack. When isosorbide is polymerized with carbonate linkages, it forms poly(isosorbide carbonate), or PIC, a polycarbonate with excellent transparency and thermal properties. But PIC has a critical flaw that has long limited its commercial appeal: it is hard and brittle. Its molecular chains are stiff and pack tightly, which means the material resists bending and shatters rather than stretches. For decades, that brittleness has confined PIC to the margins of the plastics market, useful for rigid applications but useless for films, bags, or anything requiring flexibility.

The Chiba-led team’s solution was to design a plasticizer — an additive that slips between polymer chains and allows them to slide past one another, softening the material. Plasticizers are among the oldest tools in polymer science; the phthalates that made polyvinyl chloride flexible are the most famous examples, and their environmental and health concerns are well documented. What makes the new plasticizer different is that it is not merely a benign additive. It is a dual-functional molecule, built from the same isosorbide unit at its center, connected to triethylene glycol units on both sides through carbonate linkages. Because it shares the same chemical architecture as the polymer itself, it does not just soften the plastic — it participates in the same downstream chemistry, meaning it too can be converted into fertilizer components after use.

The mechanical results were striking. Adding the plasticizer increased the material’s elongation at break from 4.3 percent to 45.2 percent, meaning the plastic became more than ten times more stretchable. In practical terms, a material that once snapped under modest deformation can now be drawn out substantially before failing. That transformation matters enormously for real-world applications. Flexible products such as agricultural mulch films, seedling pots, plastic bags, and packaging materials dominate the plastic waste stream, and a brittle polymer could never serve those roles. The researchers acknowledge that further improvement of the mechanical properties will be important for expanding the range of potential applications, but they believe these properties could be tailored by designing related polymers and plasticizers — opening a design space in which flexibility, durability, and end-of-life chemistry can be tuned together rather than traded off against each other.

The truly novel step, however, happens after the plastic’s useful life is over. When the plasticized PIC is treated with aqueous ammonia at 90 degrees Celsius for 24 hours, the carbonate linkages in both the polymer and the plasticizer are broken down. The products of this reaction are mainly isosorbide and urea — and urea is one of the world’s most widely used nitrogen fertilizers. This is a fundamentally different paradigm from biodegradable plastics. Biodegradable materials are designed to gradually fragment and be consumed by microorganisms, a process that can be slow, unpredictable, and dependent on environmental conditions. The new material, by contrast, functions as a conventional plastic throughout its service life and is converted into fertilizer only deliberately, through a controlled chemical treatment. Nothing degrades in the environment by accident; the material is harvested as a resource on schedule.

Crucially, the team did not stop at a laboratory-scale chemical demonstration. They took the fertilizer produced from the plastic and used it directly — without separation or purification — to grow plants. Two species were tested: Arabidopsis thaliana, the standard model organism of plant biology, and komatsuna, an edible leafy vegetable of the Brassica rapa family that is a staple of Japanese agriculture. The growth achieved with the plastic-derived fertilizer was on par with that achieved using commercial urea fertilizer. That is a significant result, because it demonstrates that the conversion products are not merely chemically identifiable but agronomically functional, delivering nitrogen to crops as effectively as the synthetic fertilizer that industrial farming depends upon.

The implications reach beyond a single polymer system. Nitrogen fertilizer production is itself an energy-intensive industry, dominated by the Haber-Bosch process, which consumes vast quantities of natural gas to fix atmospheric nitrogen. Meanwhile, agricultural plastics — mulch films, greenhouse coverings, nursery pots — are notoriously difficult to recycle because they are contaminated with soil and degrade during use. A system in which agricultural plastics are collected after use and converted on-site or nearby into fertilizer would close a loop between two of the most resource-intensive sectors of the modern economy. The researchers envision a future in which agricultural and domestic plastic waste is routinely converted into fertilizers, creating a circular system that supports local food production. Plastic waste from a greenhouse could, in principle, feed the next season’s crops grown under that same greenhouse.

Dr. Aoki framed the work as a shift in how society should think about materials altogether. “We are at a critical turning point in the history of plastics,” he said, noting that current strategies like reduction and traditional recycling are important but inherently “passive” and do not offer active environmental benefits. “We wanted to move toward an ‘active’ environmental contribution by designing materials that solve the plastic waste problem while simultaneously addressing resource depletion and supporting sustainable agriculture.” In that framing, the plastic is not a liability to be managed but a stored resource — a slow-release package of carbon and nitrogen waiting to be unlocked. “We anticipate this research to lead to a fundamental paradigm shift where plastics are no longer viewed as ‘waste’ but as a ‘valuable resource for food production,'” Dr. Aoki said.

There are, of course, hurdles between laboratory demonstration and widespread adoption. The mechanical properties, while dramatically improved, still fall short of the most demanding flexible-packaging requirements, and the researchers themselves note that future studies should focus on developing PIC-related plastics whose properties can be tuned to meet the requirements of different applications. Scaling ammonia treatment to industrial volumes, collecting used plastic efficiently, and ensuring the economics work against cheap conventional urea are all open questions. But the conceptual breakthrough is what matters most: the team has shown that a plastic’s end-of-life can be designed as a beginning. The study was supported by the Japan Science and Technology Agency through its Core Research for Evolutionary Science and Technology program and its University Startup Creation Fund Project, and the authors declared no competing interests. If materials like PIC and its plasticizer can be refined, the plastic bag or mulch film of the future may not be destined for a landfill or an incinerator — it may be destined for the field, returning its atoms to the soil as food for the next harvest.

Subject of Research: A bio-based isosorbide polycarbonate plastic system designed to be chemically converted into fertilizer after use

Article Title: A plastic–plasticizer system that transforms into fertilizer after use

Article References: A plastic–plasticizer system that transforms into fertilizer after use. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: plastic waste, bio-based plastic, isosorbide, plasticizer, fertilizer, chemical recycling, poly(isosorbide carbonate), urea, sustainable agriculture, circular economy, Chiba University, Scientific Reports

The new material, christened ISSATE for Isosorbide-Succinic anhydride-Tetra epoxy, begins its life as isosorbide, a rigid bicyclic sugar alcohol produced industrially from starch, and succinic anhydride, a bio-based chemical readily obtained from furan derivatives. In a three-step synthetic route, the researchers first reacted the two hydroxyl groups of isosorbide with succinic anhydride at 120 degrees Celsius without any solvent, yielding a diacid intermediate in 87 percent yield. This intermediate was then coupled with an allyl-functional trimethylolpropane derivative using a carbodiimide-mediated esterification, and finally the four pendant allyl groups were converted into epoxide rings through oxidation with meta-chloroperoxybenzoic acid. The result is a colorless, viscous liquid bearing four epoxy groups arranged around the rigid isosorbide core, a molecular architecture that no previously reported isosorbide-based diepoxide has matched.

The tetrafunctional design is the heart of the innovation. Where DGEBA carries only two reactive epoxide ends, ISSATE presents four, dramatically increasing the density of reactive sites available for crosslinking. When cured, this higher functionality translates into a tighter, more densely connected polymer network. At the same time, the succinic linkages threaded through the molecule act as flexible spacers, softening what would otherwise be an excessively brittle structure. The calculated biomass resource carbon content of the resin itself stands at 36.8 percent, and when combined with its curing agent in a complete formulation, the bio-based carbon fraction climbs to approximately 50 percent, compared with a mere 19.2 percent for the conventional DGEBA formulation it was benchmarked against.

Crucially, the researchers did not stop at a bio-based resin; they also chose a bio-based hardener. The curing agent, 1,8-p-menthanediamine or MTDA, is derived from turpentine sourced from pine gum and pine wood. Mixing the resin and hardener in stoichiometric proportions, degassing, and curing through a staged thermal schedule of 80, 120, and finally 160 degrees Celsius produced a rigid, high-performance thermoset. Fourier-transform infrared spectroscopy confirmed the chemistry: the characteristic epoxide peak near 910 wavenumbers nearly vanished after curing, while a new secondary hydroxyl band emerged, the unmistakable signature of the epoxy-amine reaction. A faint residual epoxide signal remained, which the team attributes to the 85 percent purity of the MTDA mixture of cis and trans isomers rather than to incomplete network formation.

One of the most practically significant findings concerns processability. At room temperature, ISSATE flows at a viscosity of 3175 centipoise, substantially lower than the 4763 centipoise measured for DGEBA. Lower viscosity matters enormously in industrial settings, where resins must wet fibers in composite manufacturing, fill intricate molds, and mix uniformly with hardeners without the addition of reactive diluents or solvents. The extended succinic segments appear to be responsible, granting the molecule enough conformational freedom to slide past its neighbors. Differential scanning calorimetry, analyzed with both the Kissinger and Ozawa kinetic methods, revealed a further bonus: the activation energy of the ISSATE-MTDA curing reaction is lower than that of the DGEBA-MTDA system. The researchers attribute this to the tetrafunctional structure providing more reactive sites, the enhanced molecular mobility imparted by the succinic extender, and the improved accessibility of the epoxide groups to the amine hardener, in contrast to the sterically restrictive aromatic backbone of DGEBA.

Mechanical testing told an equally encouraging story. Tensile specimens prepared according to ASTM D638 type V standards showed that the ISSATE-MTDA thermoset achieves a tensile strength of 73.33 megapascals, edging out the 70.67 megapascals recorded for DGEBA-MTDA. More striking still is the elongation at break: the bio-based material stretched 15.68 percent before failing, versus 9.41 percent for the conventional system, a roughly 66 percent improvement in ductility. The stress-strain curve of the ISSATE sample even displays a yield point, a behavior more typical of tough engineering thermoplastics than of brittle epoxy networks. The flexible succinic segments act as built-in tougheners, absorbing deformation energy that would otherwise propagate cracks. Tensile modulus, a measure of stiffness, came in at 892 megapascals for the bio-based system against 911 megapascals for DGEBA, a negligible penalty that keeps the new resin firmly in the realm of structural materials.

Dynamic mechanical analysis added nuance to the picture. The storage modulus of the ISSATE-MTDA network at room temperature and its calculated crosslinking density both marginally exceed those of the DGEBA reference, consistent with its higher functionality. However, the flexible succinic segments cause the storage modulus to decline more rapidly with temperature, and the glass transition temperature of the bio-based thermoset falls below that of its petroleum counterpart. Interestingly, both systems exhibited dual peaks in their damping curves, which the researchers link to the cis and trans configurations of the MTDA hardener. The trans isomer, with its extended molecular shape, creates regions of greater free volume and chain mobility that depress the transition temperature, while the more compact cis isomer contributes to the higher-temperature relaxation. This subtle interplay between hardener stereochemistry and network architecture offers a tunable handle for future formulation design.

Thermal stability, often the Achilles heel of bio-based polymers, proved robust. Thermogravimetric analysis showed that the ISSATE-MTDA system begins to lose mass at 315.42 degrees Celsius, defined at 2 percent weight loss, compared with 332.15 degrees Celsius for DGEBA-MTDA. The slightly earlier onset stems from the ester linkages in the ISSATE backbone, which are inherently more susceptible to thermal cleavage than the aromatic ether bonds of DGEBA. Yet at the 5 percent mass-loss threshold, the bio-based resin still withstands approximately 335 degrees Celsius, comfortably within the high-temperature range expected of serious epoxy thermosets. For adhesives, coatings, and composite matrices that rarely see sustained service above 150 degrees Celsius, this margin is more than adequate, and the trade-off buys sustainability without sacrificing the thermal envelope that matters in practice.

The implications reach well beyond a single laboratory synthesis. Epoxy thermosets are notoriously difficult to recycle because their crosslinked networks resist melting and reshaping, which means that the two million tons produced annually eventually end up in landfills or incinerators. Replacing even a fraction of that volume with resins built from isosorbide, succinic anhydride, and turpentine-derived amines would shift a substantial slice of the thermosetting industry away from fossil carbon and away from bisphenol A, a compound whose endocrine-disrupting reputation has already prompted regulatory restrictions in consumer products worldwide. The Korean team, supported by the Ministry of Trade, Industry, and Energy, frames ISSATE as a promising sustainable alternative to DGEBA-based systems, and the data support that framing: comparable or superior tensile strength, modulus, and elongation, high decomposition temperatures, lower viscosity, faster curing kinetics, and a formulation that is half renewable carbon by composition.

Challenges remain before ISSATE can challenge DGEBA at industrial scale. The multi-step synthesis involves column chromatography purification, a technique that is economical in the laboratory but costly at the ton scale, and the overall yield across three steps must be optimized for commercial viability. The lower glass transition temperature may also disqualify the current formulation from the hottest service environments, such as aerospace primary structures, where DGEBA-based systems with aromatic amine hardeners still reign. Nevertheless, the study demonstrates a principle that resonates across green chemistry: molecular design, not merely feedstock substitution, can close the performance gap between bio-based and petroleum-derived materials. By pairing a tetrafunctional sugar-derived epoxide with a flexible succinic extender and a pine-derived diamine, the researchers have shown that the next generation of epoxies need not ask industry to choose between performance and planetary responsibility. As pressure mounts to decarbonize the chemical sector, resins like ISSATE offer a concrete, measurable path forward, one epoxy group at a time.

Subject of Research: Synthesis and characterization of a tetrafunctional bio-based epoxy resin from isosorbide and succinic anhydride as a sustainable alternative to DGEBA

Article Title: A tetrafunctional bio-based epoxy from isosorbide and succinic anhydride: synthesis, properties and DGEBA comparison

Article References: Toan, M., Kwon, K., & Shin, S. (2025). A tetrafunctional bio-based epoxy from isosorbide and succinic anhydride: synthesis, properties and DGEBA comparison. Advances in Industrial and Engineering Chemistry, 1(1), Article 5. https://doi.org/10.1007/s44405-025-00006-z

Image Credits: AI Generated

DOI: 10.1007/s44405-025-00006-z

Keywords: bio-based epoxy resin, isosorbide, succinic anhydride, DGEBA, tetrafunctional epoxy, thermoset, 1,8-p-menthanediamine, renewable polymers, mechanical properties, thermal stability, curing kinetics, sustainable materials