17/03/2025

Car tires, replacement hip joints, and bowling balls – all these products rely on thermosets, a class of plastics known for their extreme durability. However, their crosslinked polymer structure makes them impossible to recycle, leading to landfill waste and environmental concerns.

Researchers in the College of Arts and Sciences from Cornell University have developed a sustainable alternative: a bio-based, fully recyclable thermoset material. This breakthrough, published by Reagan Dreiling, a doctoral student in the field of chemistry and first author of “Degradable Thermosets via Orthogonal Polymerizations of a Single Monomer,” in Nature on January 29, addresses the fundamental issue of thermosets' non-recyclability by offering a material that retains durability while being chemically degradable and reusable.

“We’ve spent 100 years trying to make polymers that last forever, and we’ve realized that’s not actually a good thing,” said Brett Fors, professor of chemistry and chemical biology in the College of Arts and Sciences and corresponding author of the paper. “Now we’re making polymers that don’t last forever, that can environmentally degrade.”

A Game-Changer for the Circular Economy

Current Challenge: Traditional thermosets, which account for 15-20% of global polymer production, cannot be recycled.

New Solution: A bio-sourced material based on dihydrofuran (DHF), a monomer derived from biological sources, enables complete chemical recycling and environmental degradation.

Key Innovation: The novel polymerization method allows two successive reactions from a single monomer, yielding both flexibility and strength in the final material.

How It Works: Dual-Phase Polymerization

Phase: DHF undergoes polymerization to form a flexible, soft material that can be completely recycled with heat and degraded by acid.
Phase: Remaining DHF monomers interlink to create a rigid, durable thermoset with high strength.
Light-Controlled Properties: By adjusting the intensity and duration of light exposure, the material's hardness and recyclability can be fine-tuned.

Comparable Performance, Superior Sustainability

DHF-based thermosets demonstrate mechanical properties similar to conventional high-density polyurethane and ethylene propylene rubber, widely used in electronics, packaging, and automotive applications. However, unlike traditional thermosets, these new materials:

Break down naturally in the environment
Enable full chemical recycling back into monomers
Offer tunable mechanical properties for various industrial applications

Future Applications and Industry Potential

The research team is now exploring further applications, including 3D printing compatibility and expanding material properties with additional monomers. This innovation paves the way for a sustainable shift in the plastics industry, reducing reliance on petroleum-based feedstocks and advancing circular economy principles.