Smells like progress: Making sustainable polymers from fragrant molecules

On a sustainability scale of one to 10, using molecules found in plants to formulate resins is an 11.

And according to researchers at the University of Birmingham’s School of Chemistry in England, it’s doable. The research team has developed a technique for extracting molecules found in the essential oils of a wide variety of plants – particularly conifers and fruit trees – to produce organic polymers to replace plastics made from petrochemicals.

Photo Credit: University of Birmingham

Called terpenes, these molecules have often traditionally been used in fragrances, cosmetics, and other household products. But even with these, because they’re tricky to extract and process, synthetic versions are often substituted. The researchers believe they’ve devised a technique for extracting the molecules and converting them into stable resins, however, by combining them with sulfur-based organic compounds called thiols, which causes the resins to be activated by light into forming a solid material.

“We need to find sustainable ways of making polymer products that do not rely on petrochemicals,” lead researcher Professor Andrew Dove said. “Terpenes have been recognized as having real potential in this search and our work is a promising step towards being able to harness these natural products.”

Processing the terpenes in this way makes them particularly useful in a 3D printing process called stereolithography, where objects are built up in multiple layers and fused together under UV light to form 3D objects. “We have successfully 3D printed [terpenes] in a vat polymerisation process, with minimal shrinkage but with a wide spectrum of thermomechanical behaviours possible through the tuning of the material composition and thermal curing profiles utilized,” the team said in a report published in the September 2019 issue of Polymer Chemistry. “Possible further avenues of exploration indicates that these materials have potential as biomedical or commercial materials with environmentally-friendly qualities…[including] 3D printable antimicrobial agents, recyclable printing resins, optically transparent printed parts, and even biomaterials with tunable thermomechanical and surface properties.”  And they could also be ideal for part prototyping, the team added.

Challenges remain, however. Since different terpenes produce different material properties, the next step for the team is to investigate those properties more fully to better control them.

But if the research has a ways to go before commercialization, the idea of making sustainable polymers from fragrant molecules definitely passes the smell test so far.