Reviewed by Lexie CornerJan 31 2025
A recent study published in Nature by researchers at Cornell University presents a recyclable and degradable alternative to conventional thermoset plastics using a bio-sourced monomer, dihydrofuran (DHF). The material retains the mechanical durability of traditional thermosets while enabling chemical recycling and natural degradation, addressing the environmental impact of non-recyclable petrochemical-based plastics.
Thermoset plastics, used in applications such as bowling balls, car tires, and medical implants, are known for their high durability. These materials account for approximately 15–20 % of global polymer production and derive their stability from a crosslinked polymer network. However, this same structure makes them inherently unrecyclable.
Currently, zero percent of the world’s thermoset materials are recycled–they are either incinerated or thrown in landfills.
Brett Fors, Professor and Study Corresponding Author, College of Arts and Sciences, Cornell University
To address the recyclability limitations of conventional thermosets, the Fors lab developed a bio-sourced alternative that retains the durability and malleability of crosslinked thermosets while remaining chemically recyclable and biodegradable.
The whole process, from creating to reusing, is more environmentally friendly than current materials.
Reagan Dreiling, Doctoral Student and Study First Author, Cornell University
The study focuses on dihydrofuran (DHF), a monomer derived from biological sources that could serve as a competitive alternative to petroleum-based feedstocks. Fors and his research team developed a polymerization process that sequentially converts DHF into a recyclable polymer and then into a crosslinked thermoset.
Dreiling initiated the process using DHF, a cyclic, double-bonded monomer, as the starting point for two distinct polymerization steps. In the first step, ring opening polymerization converts DHF into a long-chain polymer. This intermediate material is soft, flexible, and can be fully chemically recycled through heat and acid treatment.
In the second polymerization step, unreacted DHF monomers contribute to crosslinking, forming a mechanically strong and durable thermoset. This process retains the rigid cyclic structure of DHF while enabling eventual environmental degradation and thermal recyclability.
The polymerization reactions are light-initiated and controlled, allowing tunability in material properties. Dreiling said, “It is so easy. Just by changing the amount of time you run each reaction for, the amount of catalyst you put in each reaction, and the intensity of light you use, you can get a wide scope of properties through a simple process.”
Fors explained that increased light exposure enhances crosslinking, producing a harder material. Unexposed portions remain fully chemically recyclable, while areas exposed to lower light levels exhibit increased flexibility.
DHF-based thermosets demonstrate properties comparable to commercial thermosets, such as ethylene propylene rubber (used in hoses and automotive weatherstripping) and high-density polyurethane (used in electronics, packaging, and footwear).
According to Fors, DHF-based materials support a circular materials economy, distinguishing them from conventional petrochemical thermosets. These materials can be chemically recycled back to their monomer form and, when inevitably released into the environment, degrade into non-toxic components.
The research team is exploring applications such as 3D printing and modifying the polymer composition by incorporating additional monomers to further enhance material properties.
We have spent 100 years trying to make polymers that last forever, and we have realized that is not actually a good thing. Now we are making polymers that do not last forever, that can environmentally degrade.
Brett Fors, Professor and Study Corresponding Author, College of Arts and Sciences, Cornell University
The research was funded by the National Science Foundation (NSF) and the NSF Graduate Research Fellowship Program and made use of the Cornell NMR Facility and the Cornell Center for Materials Research, supported by the NSF’s Materials Research Science and Engineering Centers program.
Kathleen Huynh, an NSF Research Experience for Undergraduates student from San Jose State University, participated in the study during a summer visit funded by the Center for Sustainable Polymers.
Journal Reference:
Dreiling, R. J., et al. (2025) Degradable thermosets via orthogonal polymerizations of a single monomer. Nature. doi.org/10.1038/s41586-024-08386-w.