A Novel Monomer Family for High-Performance, Degradable Thermosetting Polyester Resins

Background

Thermosets, or cross-linked polymers, are a class of materials with a permanent molecular architecture that can impart additional dimensional stability, enhanced tensile and impact strengths, improved elasticity, and reduced creep compared to their linear counterparts. These properties are essential for a wide range of applications in insulators, adhesives, pipes, construction and transportation.

The thermoset industry has been growing dramatically, with cross-linked polymers now constituting 15-20% of all polymers produced. However, the same thermomechanical properties responsible for their resistance and robustness prevent them from being recycled or reprocessed, and most thermosets are incinerated or landfilled. The lack of traditional waste management routes, coupled with the higher value potential applications, suggest that degradable cross-linked polymers could more readily offer a sustainable end-of-life solution.

This technology accesses new cross-linked systems that retain the high performance of thermoset materials and their composites whilst adding controlled degradation through selective chemical recycling or biodegradation routes.

Technology Overview

A team at the University of Manchester have developed a family of cross-linkers for the synthesis of degradable polyester resins. A particular compound family is used as a cross-linking monomer for ring-opening polymerisation, and polymers comprising units derived from that monomer.

The inventors have identified compounds used as cross-linkers which imbue superior mechanical properties to polymers as compared to other cross-linking agents known in the art, especially those with similar functionality. The cross-link and monomer choice can tune material performance, accessing hard and tough thermosets or elastomeric systems. The performance of tough resins is particularly unique, matching the properties of classical epoxy or phenol-formaldehyde thermosets and opening up new applications as structural composite materials.

The use of the compounds may provide new affordable routes to fully degradable elastomeric and rigid polymeric materials from sustainable sources. The cross-links and co-monomers can all be renewably sourced and are inherently inexpensive. Triggered degradation can facilitate selective chemical recycling to monomers, hydrolytic degradation or full biodegradation as end-of-life pathways.

Further Details:

https://pubs.acs.org/doi/full/10.1021/acs.macromol.2c02560

Stage of Development

The materials have been developed at a lab (multi-gram) scale as proof of concept. A patent has been filed covering the use of the cross-linking monomer and the method of production. Initial performance testing has been undertaken with highly positive indicative results. Scale-up and further testing are planned.

Benefits

• Thermal and mechanical properties comparable to those of commercially available non-degradable thermosets
• Inexpensive and bio-based monomer sources
• Degradable: potential to recover monomer precursors and reinforcement agents (carbon fibre or other fillers) at end-of-life through multiple pathways

Applications

• Automotive
• Aerospace
• Building materials
• Composites
• Multi-materials

Opportunity

The University of Manchester Innovation Factory seek commercial partners to work with them to develop/test/licence the technology.