Japanese polymer breakthrough: Reversible plastic creation “paves the way for sustainable future”
24 Nov 2023 --- Japanese researchers have developed a novel approach for preparing supramolecular polymers (SPs) at high concentrations, addressing the longstanding challenge of low solubility in monomer compounds.
SPs, molecular assemblies held together by non-covalent bonds, are poised to revolutionize the plastics industry due to their high recyclability.
SPs are distinct from traditional covalent polymers, as Atsushi Isobe, the first author of the study, tells us: “Unlike the traditional polymers in which repeating units called monomers are covalently linked, SPs are formed by linking monomers one-dimensionally through ‘non-covalent’ bonds showing reversible nature (supramolecular polymerization).”
“Therefore, SPs can be readily degraded into monomers by heating or diluting their solution and subsequently cooling or concentrating the resulting monomer solution to reconstruct them. This reversibility allows SPs to be readily degraded into monomers, offering a key advantage in terms of recyclability.”
New polymers for easier recycling
A supramolecular polymer can be understood as a chain of molecules that can link and unlink easily, like interlocking paper clips. This reversibility is a crucial feature of SPs, making them potentially more recyclable than traditional plastics.
Japanese researchers demonstrate coformer methodology for supramolecular polymers.
In response to questions about the packaging industry application, Isobe highlights the importance of developing novel polymer materials for easy recycling: “From an environmental perspective toward the realization of a sustainable society, it is essential to develop novel polymer materials that can be easily recycled instead of the covalent polymers with low degradability.”
“To overcome this problem, SPs are expected to be one of the ideal materials. However, since supramolecular polymers are generally formed in diluted solutions, evaluating their functionalities and application is challenging. If practical SPs are produced on an industrial scale based on this study, they can be employed as novel packaging materials.”
The study was published in Angewandte Chemie International Edition.
Coformer for solubility enhancement
Research team lead professor Shiki Yagai from the Institute for Advanced Academic Research at Chiba University, Japan, underscores that the study could pave the way for developing improved recyclable plastics for a sustainable future.
“Using a coformer can facilitate the large-scale production of SPs, leading to evaluating their functionalities. The application of supramolecular polymers can contribute to producing novel plastic materials showing high recyclability originating from the reversibility of monomer bindings and recycling them with lower energy consumption,” says Yagai.
Addressing technical details, Isobe explains the impact of polymorphism on solubility, particularly in industries like pharmaceuticals: “If a molecule organizes into a crystalline polymorphic state with high structural order, the molecules become poorly soluble.”
To overcome this, the team applied the coformer approach to a supramolecular monomer with poor solubility, designing a coformer molecule to enhance solubility through co-aggregation.
Isobe further details the modifications made to address poor solubility: “We demonstrated that the coformer approach enhanced the solubility of the monomer molecule with poor solubility associated with the formation of a crystalline polymorphic state during the preparation of supramolecular polymers, enabling the preparation of supramolecular polymers at high concentrations.”
By Radhika Sikaria
