Adolphe Merkle Institute researchers have developed new mixtures or “blends” of supramolecular polymers that can self-heal or be more easily recycled, but that are as tough as conventional plastics, making them potentially suitable for real-world applications.

Supramolecular polymers are formed through non-covalent, directional interactions between small molecules that are equipped with “sticky” binding motifs. These moieties stick to one another, leading to an assembly into long-chain, polymer-like structures. This process is completely reversible, which enables functions such as healing, repair, or recycling. While such properties are extremely interesting, the polymers usually fail to match the mechanical properties of conventional commodity plastics, making them unsuitable for use in everyday applications.

The researchers from the AMI Polymer Chemistry and Materials group have overcome this hurdle by combining metallosupramolecular polymers with dissimilar mechanical properties that feature the same binding motif. Assembling them creates materials that combine hard and soft domains on a microscopic level. This yields a tougher, stronger material that is more resistant to mechanical deformation than its constituent elements alone. Combining the building blocks at different ratios also means that the mechanical properties can be easily varied. It is also possible to mimic the complex structures observed in some of Nature’s best materials and create objects with specifically and locally modulated mechanical behavior.

“Our polymers show that with the right building blocks, supramolecular materials can finally compete with conventional commodity plastics,” says group leader Dr. Stephen Schrettl, who led the research. “Our discovery has wide-ranging implications, since the concept appears to be general, and promises to move supramolecular polymers much closer to technological exploitation.”

The results of this research have been published in the leading journal Nature Communications.

Reference: Sautaux, J.; Marx, F.; Gunkel, I.; Weder, C.; Schrettl, S. Mechanically robust supramolecular polymer co-assemblies, Nature Communications , 2022, 13, 356.