Researchers at Cornell University have developed a recyclable alternative to thermoset plastics, a class of durable materials commonly used in car tires, replacement hip joints and bowling balls. Thermosets are characterized by a cross-linked polymer structure that ensures excellent strength and service life. However, this structure also makes traditional petrochemical-based thermosets (which account for 15%-20% of total polymer production) impossible to recycle.
"Currently, there is zero recycling rate for thermoset materials globally, and they are either incinerated or thrown into landfills," said Brett Foss, professor of chemistry and chemical biology at Cornell University.
Flowserve Labs has responded to this environmental challenge by creating an alternative made from biosourced materials that have the durability and ductility of cross-linked thermosets but are easily recycled and degraded. The paper was published in Nature.
Foss's group studied dihydrofuran (DHF), a monomer (or chemical building block) that can be made from biomaterials that could eventually compete with petroleum feedstocks.
Dreiling uses DHF, a cyclic monomer with double bonds, as a building block for two consecutive polymerizations. The cross-linked polymer produced by the second polymerization can be recycled through heating and can degrade naturally in the environment.
DHF thermosets have properties comparable to commercial thermosets, including high-density polyurethane (used in electronics, packaging, footwear, etc.) and ethylene-propylene rubber (used in garden hoses and automotive weatherstripping).
Foss said DHF-based materials offer a circular economy of use compared to current petrochemical thermosets. The material is chemically recyclable and can be reformulated into its constituent monomers and used from scratch. When some materials inevitably leak into the environment, these materials degrade into harmless components over time.
Researchers are working on applying this DHF-based material to 3D printing. They are also experimenting with using more monomers to expand the material's properties.
"We spent 100 years trying to make polymers that last forever, but we realized that wasn't actually a good thing," Foss said. "Now, we're making polymers that are not eternal but degrade in the environment."
Compiled from /ScitechDaily
DOI:10.1038/s41586-024-08386-w