(All image credits: King Abdullah University of Science and Technology).

30 Oct 2023 — King Abdullah University of Science and Technology (KAUST), Saudi Arabia, and two Chinese companies operating in the plastics sector are developing “green plastics” of high molar mass called aliphatic polycarbonates (PCs). 

Shandong Lianxin Environmental Protection Technology and Hangzhou Hecai Technology are the two companies participating in the project. Professor of chemistry Yves Gnanou, Dr. Xiaoshuang Feng and their research team at KAUST have developed an innovative method to create PCs without using toxic metals, which are typically used in the production of similar plastics. The aliphatic PCs are unique because they are made using carbon dioxide and raw materials from sustainable sources. 

Dr. Feng explains that regular polycarbonates made with metal catalysts cannot be used in applications like food or medical products because of the metals they contain. However, their PC is free of metals and an “excellent” barrier to oxygen and moisture, making it suitable for plastic packaging, entailing items that need to be protected from oxidation. The solution includes up to 45% of CO2, meaning products help reduce carbon footprint when manufactured. 

Metal-free biomedical packs
Gnanou tells Packaging Insights that the metal-free polycarbonates are mainly aimed for applications in the biomedical area, for applications such as blood bags, syringes and sutures “because they are excellent barriers against oxygen and moisture and do not contain any metal residue.” 

“They can be used for packaging as well (in particular for food packaging), but the cost factor can be a limit at this time. Unlike most currently used plastics, these CO2-based polycarbonates are biodegradable, which is another advantage. Under contact with an enzyme, they will degrade and release carbon dioxide and water,” explains Gnanou.

The project will be commercialized in two years, with the next year spent building the facility and producing 1 ton of bioplastics. 

The projected timescale is two years to full commercialization, with the next year spent building the facility and producing 1 ton of the material. 

Gnanou explains that commercialization will start after completion of the 1- to 3-ton pilot production phase which is expected to last approximately two years. “Today, the Shandong Lianxin company located in Zibo, China, is synthesizing polycarbonates using KAUST’s non-metallic catalyst in 50-liter scale reactors to master the entire production process.”

“The general manager said that his company will repeat at least 50 times such polycarbonate production in 50-liter reactors and master all chemical engineering aspects (heat transfer, temperature control, drying and volatile elimination post-synthesis) before attempting to reproduce the same synthesis at 1- to 3-ton pilot scale,” he highlights.

Green chemistry for recyclables 
Gnanou says industrialization will be carried out in Taixing, China. “A plant is being built in that city of Taixing, aiming for the production of a few dozen thousand tons of CO2-based plastics.”

As a concept, “green plastics” has existed for nearly two decades, with several manufacturers embracing the principles of green chemistry to develop recyclable plastics. While solutions involving bio-based or biodegradable plastics have emerged, only a handful have achieved industrial adoption.

“I began contemplating biodegradable plastics several years ago. I’m gratified that we’ve developed a material that can be completely converted into water and CO2 through enzymatic degradation at the end of its lifecycle. Our product won’t add to the environmental challenge,” concludes Gnanou.

By Natalie Schwertheim

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