In brief

By conducting life cycle assessments for three polymer synthesis methods, A*STAR scientists have identified an environmentally sustainable process for producing biodegradable plastics.

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The dark side of green plastics

19 Nov 2021

Mapping the life cycle of biodegradable polymers can help manufacturers make data-driven decisions on the most sustainable production practices.

As the saying goes, reducing our environmental footprint should be as simple as practicing ‘reduce, reuse and recycle.’ Unfortunately, this mantra alone does not ensure sustainability or a pollution-free environment. Non-biodegradable polymers such as polystyrene and polyethylene, for instance, end up being the worst polluters, devastating fragile ecosystems.

Praveen Thoniyot, Senior Scientist and Team Leader at A*STAR’s Institute of Chemical and Engineering Sciences (ICES), believes that it is not only important to identify greener polymer alternatives, but also map their life cycles from synthesis to disposal. According to Thoniyot, such a sentiment is shared by key players in the plastic manufacturing industry.

“Studying the sustainability of polymer synthesis is gaining momentum due to the increased customer awareness, regulatory pressure on industry and opportunities to reduce costs,” explained Thoniyot. “There is [also] a lack of understanding of the environmental footprint of polymer syntheses.”

To demonstrate the feasibility of a laboratory-scale life cycle assessment (LCA), the team explored the synthesis of a promising biodegradable plastic called poly(ε-caprolactone), or PCL. Upon the recommendation of co-investigator Hsien Hui Khoo, Scientist and LCA expert at ICES, the team conducted the study using ISO 14040 and 14044 standards, an established framework for quantifying the overall sustainability of manufacturing practices.

According to first author Pancy Ang, Senior Research Engineer at ICES, laboratory-scale LCA is conducted using a cradle-to-gate system boundary, which starts with the extraction of raw materials and ends with the production of PCL homopolymer.

The researchers’ analyses allowed them to rank the three processes in terms of overall sustainability. “The hydrochloric acid-catalyzed ring-opening polymerization of ε-CL is the most environmentally sustainable route since it has the lowest environmental impact,” said Thoniyot. In contrast, the other two processes fell short on their sustainability checklist, either requiring large amounts of power or using chemicals toxic to humans.

These findings open up possibilities for future collaborations between academia and the green plastic manufacturing industry. “Laboratory-scale LCA could serve as a preliminary tool to evaluate the environmental sustainability of different technologies across domains before scaling up or commercialization,” added Thoniyot.

Taken altogether, this approach could become very useful in evaluating emerging biodegradable alternatives to phase out the current plastic materials that pollute and persist in the environment. Moving forward, the researchers plan to expand their analyses to paint a more holistic picture of the sustainability of different PCL synthesis technologies.

“In future projects, we wish to consider both the quantitative and qualitative aspects of synthesis,” concluded Thoniyot. “To our knowledge, there is no current research done on the laboratory-scale LCA comparison of existing and emerging [synthesis] technologies.”

The A*STAR researchers contributing to this work are from the Institute of Chemical and Engineering Sciences (ICES).

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Ang, P., Mothe, S.R., Chennamaneni, L.R., Aidil, F., Khoo, H.H., et al. Laboratory-scale life-cycle assessment: a comparison of existing and emerging methods of poly(ε-caprolactone) synthesis. ACS Sustainable Chemistry & Engineering 9, 669 – 683 (2020) │ article

About the Researcher

Praveen Thoniyot is a Senior Scientist and Team Leader at A*STAR’s Institute of Chemical and Engineering Sciences (ICES). In 2000, he obtained his PhD degree in organic chemistry at the National Chemical Laboratory, India, on a national fellowship from India’s Council of Scientific and Industrial Research. Thoniyot conducted post-doctoral research on a CNRS fellowship at the University of Nantes in France, where he worked on organic-inorganic hybrid materials. In 2002, he joined the Department of Chemistry and Biochemistry at the University of California, Santa Cruz, and worked on boron chemistry, polymerization chemistry and saccharide-sensing technologies. In 2005, he joined A*STAR and held various research positions before joining ICES in 2015. Thoniyot is passionate about incorporating sustainability and a systems-thinking approach into all his research projects.

This article was made for A*STAR Research by Wildtype Media Group