Growing plastic waste requires new approaches beyond traditional recycling and disposal methods. Researchers developed a flexible bio-based plastic that can be chemically converted into fertilizer after use through ammonia treatment. By adding a specially designed plasticizer, they improved the flexibility of the previously brittle plastic, increasing its potential for future applications. Importantly, both the polymer and the plasticizer can be converted into fertilizer components. The fertilizer produced from the plastic could support plant growth
Plastic waste is one of the world's fastest-growing environmental problems. According to the OECD's Global Plastics Outlook: Policy Scenarios to 2060 report, global plastic use is projected to nearly triple from 460 million metric tons in 2019 to 1.2 billion metric tons by 2060, if current trends continue. Today, reducing plastic use, recycling, and waste-to-energy processes are among the main approaches for managing plastic waste. However, these approaches are struggling to keep pace with the growing volume of plastic waste.
Addressing this challenge, a research team led by Associate Professor Daisuke Aoki from the Graduate School of Engineering, Chiba University , Japan, developed a bio-based plastic, poly (isosorbide carbonate) (PIC), that can be converted into fertilizer after use. The basic building block of the polymer, isosorbide (ISB), is a bio-based monomer synthesized from glucose. When treated with aqueous ammonia, PIC can be chemically converted into ISB and urea, and the resulting products can be used to support plant growth. However, its inherent hardness and brittleness limited its range of potential applications.
In a study that was published in Volume 16 of the journal Scientific Reports on August 18, 2026, the team overcame this limitation by developing a dual-functional, isosorbide-based plasticizer that, when added to PIC, makes the plastic softer and more flexible while preserving its ability to be converted into fertilizer after use. Importantly, not only the polymer but also the plasticizer can be converted into fertilizer components through ammonia treatment. Unlike biodegradable plastics that gradually break down, this material functions as a conventional plastic during use and is chemically converted into fertilizer only after its service life, through ammonia treatment.
The research team included Mr. Shunsuke Fujimata and Dr. Tatsuo Taniguchi from the Graduate School of Science and Engineering at Chiba University; 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, Japan.
"We are at a critical turning point in the history of plastics. While current strategies like reduction and traditional recycling are important, they are 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," says Dr. Aoki.
The plasticizer consists of an isosorbide unit at its center, connected to triethylene glycol units on both sides through carbonate linkages. Adding the plasticizer made the plastic much softer and flexible. The elongation at break increased from 4.3% to 45.2%, indicating that the material became over ten times more stretchable. While further improvement of the mechanical properties will be important for expanding the range of potential applications, the researchers believe that these properties could be further tailored by designing related polymers and plasticizers. This could allow the material to be used in flexible products such as agricultural mulch films, seedling pots, plastic bags, and packaging materials.
Furthermore, the developed plasticizer did not affect the material's ability to be converted into fertilizer. When the plastic was treated with aqueous ammonia at 90°C for 24 hours, the polymer and plasticizer broke down into mainly ISB and urea.
The researchers used the fertilizer produced from the plastic directly, without separation or purification, to successfully grow a model plant, Arabidopsis thaliana, and the edible vegetable komatsuna (a variety of Brassica rapa). The growth of the plants was on par with that achieved using commercial urea fertilizer.
These results are promising and could lead to a new generation of plastics that are viewed as a resource rather than waste. 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.
"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," says Dr. Aoki. The researchers also note that future studies should focus on developing PIC-related plastics whose properties can be tuned to meet the requirements of different applications.
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About Associate Professor Daisuke Aoki
Dr. Daisuke Aoki at the Graduate School of Engineering, Chiba University, specializes in polymer science, with broad research interests ranging from supramolecular chemistry and polymer topology to sustainable polymer materials. His research has explored the development of functional polymeric materials by harnessing supramolecular structures and polymer topology. More recently, his work has expanded to sustainable plastics and chemical recycling technologies, including approaches to convert waste plastics into fertilizers, creating new pathways for resource circulation and supporting sustainable agriculture. He has authored more than 100 scientific papers across these areas of polymer science.
Funding:
Japan Science and Technology Agency, Core Research for Evolutionary Science and Technology (CREST), JPMJCR22L1. Japan Science and Technology Agency, University Startup Creation Fund Project: Project Promotion Type – Entrepreneurial Demonstration Support, JPMJSF2302.
Reference:
Authors: Shunsuke Fujimata1, Yoshiki Tokonami2, Raj Kishan Agrahari3, Toyokazu Tsutsuba1, Kazuaki Rikiyama1, Norio Tomotsu1, Tatsuo Taniguchi1, Takehiro Kamiya*3, Mizuhiko Nishida*2, and Daisuke Aoki*1,4
Affiliations: 1Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University, Japan
2Field Science Center, Graduate school of Agricultural Science, Tohoku University, Japan
3The Laboratory of Plant Nutrition and Fertilizers, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Japan
4Research Center for Space Agriculture and Horticulture, Chiba University, Japan
DOI: 10.1038/s41598-026-63638-1
