# Synthesis, Properties, and Metathesis Activity of Polyurethane Thermoplastics and Thermosets from a Renewable Polysesquiterpene Diol

## TL;DR

This paper introduces a new type of polyurethane made from renewable materials that can be chemically broken down, offering a sustainable alternative to traditional plastics.

## Contribution

A novel renewable polysesquiterpene diol is developed for polyurethanes that can be chemically deconstructed.

## Key findings

- Polyurethanes made with HTPCR show thermal and rheological properties similar to conventional materials.
- Both thermoplastic and thermoset PUs can be chemically degraded via ruthenium-mediated metathesis.
- The use of β-caryophyllene enables sustainable and reprocessable polyurethanes.

## Abstract

Polyurethanes (PUs)
are the sixth most commonly utilized plastic
class, yet ∼80% of commodity material is landfilled or incinerated
at the end of life. Disposal of thermosets is particularly problematic
as cross-linking prevents the repurposing of disposed material. Thus,
there is considerable interest in the development of PUs derived from
inexpensive feedstocks that can be inherently chemically deconstructed.
Ring opening metathesis polymerization (ROMP) of the naturally occurring
sesquiterpene β-caryophyllene in the presence of dihydroxy chain
terminators afforded the polyol hydroxy-terminated polycaryophyllene
(HTPCR). Incorporation of HTPCR into PUs through reaction with polyisocyanates
produced polymers with thermal and rheological properties comparable
to commodity materials. The feasibility of chemical degradation of
both thermoplastic and thermoset materials was also demonstrated through
ruthenium-mediated metathesis, utilizing the metathesis-active olefins
within the repeat caryophyllene monomer unit. Overall, this work highlights
the value of biorenewable, chemically reprocessable polysesquiterpenes
in the PU space.