Japanese scientists derive chemically recyclable polymers from plant cellulose

27 Mar 2024 --- Researchers from Hokkaido University, Japan, have unveiled a novel method for synthesizing chemically recyclable unnatural polysaccharides using levoglucosenone (LGO) and dihydrolevoglucosenone (Cyrene), both derived from cellulose.

The team’s findings promise advancements in sustainable polymer material development, offering a solution to the global challenges posed by plastic waste and fossil fuel depletion.

Polysaccharides, found in biomass resources, have long been recognized for their potential in sustainable material production. However, the researchers share that synthesizing unnatural polysaccharide analogs with tailored properties has proven challenging due to complexity and scalability issues. 

The Hokkaido researchers leveraged LGO and Cyrene, which offer a straightforward route to various polysaccharides with minimal synthetic steps. They developed a chemical process to convert LGO and Cyrene into various unnatural polysaccharide polymers. 

“For the potential application, as the materials are rigid it may be difficult to use them as flexible plastic materials, such as plastic bags, so we expect they will be more suited for high-performance materials, for example for optical, electronic and biomedical applications,” assistant professor Feng Li, a corresponding author, tells Packaging Insights.

The study was published in American Chemical Society Macro Letters.

Monomer synthesization 
The study began with synthesizing monomers from Cyrene and LGO, resulting in three monomer types, each with different substitution patterns. 

Using a versatile cationic ring-opening polymerization (cROP) technique, the researchers successfully polymerized these monomers to obtain polysaccharides with tailored substituent patterns. 

The synthesized polysaccharides exhibited high thermal stability and formed amorphous solids under ambient conditions, which is ideal for processing into transparent self-standing films, according to the researchers.

“Our biggest challenges were controlling the polymerization reaction that links the smaller monomer molecules together and obtaining polysaccharide materials that are sufficiently stable for common applications while still able to be broken up and recycled by specific chemical conditions,” says Li.

He adds that the biggest surprise during the research was the high transparency of the polymer films they made, which might be crucial for the kind of specialist applications that these polymers seem most suited for. 

From left: Toshifumi Satoh, Yuta Mizukami, Feng Li, and Takuya Isono of the research team.Addressing environmental sustainability
The research demonstrates closed-loop chemical recyclability of the synthesized polysaccharides. The researchers could revert the polysaccharides to their monomeric forms with nearly quantitative yields through acid-catalyzed depolymerization. 

The findings highlight the synthesized materials’ sustainability and offer a practical solution for addressing end-of-life concerns associated with polymer materials.

The researchers believe the study opens new avenues for sustainable polymer material development, offering a promising approach to utilizing abundant biomass resources efficiently. As research continues, the team is optimistic about further refining their approach to unlock the full potential of biomass-derived polysaccharides in material science.

“We hope this work will develop a wide variety of useful unnatural polysaccharide polymers to become part of a sustainable closed loop of synthesis from biomass with efficient recycling,” Li shares.

“For production on a large scale, we are trying to collaborate with companies.” 

“For further development, as the feasible structural variations based on polysaccharides are so numerous that we would like to join forces with specialists in other research fields such as computational chemistry, artificial intelligence and automated synthesis to explore the options,” Li concludes.

By Radhika Sikaria