Plastics Derived from Pine Sap Could Help Develop Sustainable Materials

In the last 10 decades, plastics and polymers have altered the way the globe functions, right from airplanes and automobiles to computers and mobile phones, almost everything is composed of fossil fuel-based compounds.

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A research team from Florida State University (FSU) has discovered a new plastic derivative obtained from pine sap with the ability to provide a new dimension for new sustainable materials.

Justin Kennemur, an Associate Professor of Chemistry and Biochemistry who was the principal investigator of the study explaining the breakthrough, stated that the discovery was a remarkable step in the correct direction for new plastic and is a gateway resulting in several new materials.

What we know currently is this glassy, thermally stable plastic can be melted and shaped at a higher temperature and cools into a hard plastic at ambient temperatures.

Justin Kennemur, Study Principal Investigator and Associate Professor of Chemistry and Biochemistry, Florida State University

“One of the next goals is to learn some of the mechanical properties of these polymers. However, this material has many structural features that mirror the plastics we use every day, so there is promise for a multitude of applications,” added Kennemur.

The study results were published in the ACS Macro Letters journal.

“Ninety-nine percent of plastics today are produced from finite fossil fuels with increasing demand and limited geographic availability. Producing materials from renewable resources, and particularly pine sap, which may be harvested without killing the tree, is a noteworthy effort,” added Kennemur.

Alpha-pinene is the frequently occurring molecule produced from pine-sap and is extremely challenging to convert into plastic, limiting its uses. It is predominantly found in turpentine-based solvents and cleaners.

Mark Yarolimek, an FSU doctoral student in polymer chemistry who headed the study, initially, synthetically changed the alpha-pinene to produce the compound called delta-pinene.

I put alpha-pinene through a series of chemical reactions, multiple purifications, and some trial and error, which eventually proved successful in converting it to delta-pinene. Once we obtained purified liquid delta-pinene, I converted that into the resultant plastic, poly-delta-pinene, through one final chemical reaction.

Mark Yarolimek, Study Lead Author and Doctoral Student in Polymer Chemistry, Florida State University

Yarolimek and Heather Bookbinder, who worked as undergraduate researchers on the project before graduating with a bachelor’s degree in exercise physiology in 2020, have conducted a series of “polymerizations.” This covers chemical reactions to convert small liquid molecules into solid macromolecules, to test the effectiveness of this molecule in transforming into plastic.

Also, these tests quantified the amount of delta-pinene converted into plastic in a single reaction. It also showed how well the scientists were able to control the growth of the molecule, and how condition variability caused an impact on the materials.

The researchers also defined several material properties of the plastic, such as the temperature required to melt the polymers and the heat withstanding capacity before getting decomposed, including exploration of the molecular structure of the material.

Brianna Coia, a graduate researcher in the Kennemur Group, concurrently examined the delta-pinene to comprehend if it holds the ideal thermodynamic properties to experience polymerization. Using the resources from FSU Research Computing Center, Coia made density functional theory calculations, and her computational results obtained were in line with Yarolimek and Bookbinder’s experimental findings.

According to Yarolimek, conversion of such biomass molecules into new high-performance plastics, similar to the one discovered, is necessary to progress the current way of life. Already, the team has collaborated with the FSU Office of Commercialization in filing a patent for the discovered material.

“Instead of regressing to the 18^th century when petroleum runs out, the switch to biobased plastics will allow us to push further forward into what comes next,” stated Yarolimek.

According to Kennemur, developing the new biobased plastics is just a part of the conversation, the rest contributes to the complete development of plastic. Regarding this high-performance material, exhibiting a short shelf life from being biodegradable would be unsuitable, but it still requires a recycling method. This implies the possible development of the decomposition process through a chemical stimulus.

“Our research is invested in both. We make new materials, but we are also investigating their chemical recyclability. We made this new plastic, but this is just the beginning. We need to also learn how to unmake the plastic and we have plans to start investigating that,” commented Kennemur.

Kennemur said his student researchers extensively deserve the appreciation for the discovery while he was just a guide for their efforts.

Being a part of this research team was probably one of the most educational and interesting experiences I had during my time at FSU. In my opinion, hands-on experience is the most engaging way to learn and has a long-lasting effect. I will talk about the research and my role in the experience for the rest of my life.

Heather Bookbinder, Undergraduate Researcher, Florida State University

The study was financially supported by the Planning Grant Program of Florida State University, sponsored by the FSU Council on Research and Creativity. The PG program assists new directions or continued early support of ongoing research or innovative activity.

Journal Reference:

Yarolimek, M R., et al. (2021) Ring-Opening Metathesis Polymerization of δ-Pinene: Well-Defined Polyolefins from Pine Sap. ACS Macro Letters. doi.org/10.1021/acsmacrolett.1c00284.