High-biomass plastics that don’t pollute

Yokohama, Japan -- Cheap, strong, and versatile, plastic seemed like the perfect invention — until its staying power turned into a global headache. Now, YOKOHAMA National University researchers have developed a plant-based alternative that could one day offer the same benefits with a cleaner way out.

The study was published online in Nature Communications on November 27.

Plastics, or synthetic polymers, have become one of the most versatile and widely used materials in modern life, but their convenience comes with a heavy environmental and potentially health-related cost. Not only made mostly from increasingly scarce fossil fuels, plastic also does not biodegrade; instead, it breaks down into ever-smaller pieces that can linger for hundreds of years.

“Our goal was to propose a new concept for sustainable polymer synthesis by producing decomposable polymers with high biomass content and demonstrating recycling and upcycling using the decomposition products,” said Naoki Shida, associate professor at YOKOHAMA National University’s Faculty of Engineering, and one of the lead authors.

The researchers turned to phenylpropanoids — aromatic compounds that form the main components of essential oils. These plant-derived molecules are widely available and structurally diverse, making them promising candidates for producing more sustainable plastics. However, polymerizing phenylpropanoids has been a long-standing challenge.

“So far, only a few plastics with high phenylpropanoid content have been made, and most aren’t easy to recycle,” said Mahito Atobe, professor at the Faculty of Engineering and another lead author of the study.

To overcome this, the team used [2 + 2] cycloaddition polymerization, a chemical reaction during which two molecules, each with a pair of connected atoms, join together to form a four-membered ring. This reaction links small molecules, or monomers, into larger, strong, and stable polymer chains.

The resulting materials are not only heat-resistant and durable but also designed to decompose. Their unique backbone contains aromatic rings that improve their mechanical and thermal properties, cyclobutane rings for higher thermal stability, and silyl ether bonds that facilitate decomposability. Under mild conditions, the polymers can be selectively broken down through either Diels–Alder reactions or Si–O bond cleavage, yielding products that can be recycled or even upcycled into new materials.

“We demonstrated that decomposable polymers can be synthesized by homopolymerizing monomers consisting of phenylpropanoids linked by Si–O bonds,” Shida said. “This approach is applicable to various phenylpropanoids, and the polymerization reaction can be driven by diverse methods including chemical, electrochemical, and photochemical techniques.”

Their method shows that renewable plant resources can be harnessed to make plastics that are both high-performing and recyclable, paving the way toward more sustainable materials and a circular economy.

“By combining high biomass content with controlled decomposability, our approach reduces environmental burden at every stage,” Atobe said.

Looking ahead, the team plans to increase the molecular weight of the polymers, improve decomposition yields, and scale the process using flow synthesis systems for greater efficiency.

“Our ultimate goal is to establish a versatile process for synthesizing decomposable biomass polymers by advancing cost reduction and evaluating commercial viability,” Shida said.

Funding 

• Japan Society for the Promotion of Science KAKENHI Grant Nos. 21H05215 (Digi-TOS), 23H04916 (Green Catalysis Science), 23K17370, and 24H00394,
• The Society of Synthetic Organic Chemistry, Japan (DIC Award in Synthetic Organic Chemistry),
• Iketani Science and Technology Foundation,
• Fujimori Science and Technology Foundation,
• Tokuyama Science Foundation.

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YOKOHAMA National University (YNU) is a leading research university dedicated to academic excellence and global collaboration. Its faculties and research institutes lead efforts in pioneering new academic fields, advancing research in artificial intelligence, robotics, quantum information, semiconductor innovation, energy, biotechnology, ecosystems, and smart city development. Through interdisciplinary research and international partnerships, YNU drives innovation and contributes to global societal advancement.