Process Devised for Renewable, Biodegradable Plastic

Eugene Chen (Colorado State University)

22 June 2018. A chemistry lab developed a process for economically producing a polymer material from renewable sources that could replace some plastics now derived from petroleum. Eugene Chen, a professor of chemistry and research scientist Xiaoyan Tang at Colorado State University in Fort Collins, describe the process in the 11 June issue of the journal Nature Communications.

Chen and Tang report on their techniques for developing an alternative process for bacterial poly(3-hydroxybutyrate), or P3HB, a polymer produced naturally by microorganisms including bacteria and algae. P3HB has many desirable properties for medical devices and tissue engineering, notably its natural bio-friendly source and ability to degrade slowly in the body. The polymer also degrades in soil by interacting with soil bacteria, an attractive feature for disposal in landfills.

But despite these desirable qualities, P3HB so far proved to be slow and difficult to synthesize, thus limiting its use to specialty products like medical devices. To produce the material faster, Chen and Tang started with succinate, a common form of succinic acid, used in a variety of food, consumer, and commercial products. The U.S. Department of Energy also identified succinic acid as a top candidate for producing chemicals converted from sugars stored in biomass to replace chemicals made from petroleum.

The researchers derived an intermediate product from succinate, which reacts to special catalysts to produce P3HB. These catalysts, called racemic mixtures, contain compounds with equal amounts of components having non-mirrored atomic configurations. The catalysts, combined with the intermediate succinate compounds, quickly generate synthetic P3HB under ambient conditions. Tests of the synthesized P3HB show the new polymer has largely the same properties of the naturally produced material. But because the synthetic polymer can be produced quickly and cheaply, it’s a better candidate for a commodity material, as well as being derived from renewable sources and its biodegradability.

Colorado State filed a provisional patent on the process, listing Chen and Tang as inventors. Synthetic P3HB combines all three research interests in Chen’s lab: polymer science, catalytic chemistry, and green-sustainable chemistry. In April, Chen and colleagues published their findings in the journal Science of another synthetic polymer, also produced under ambient conditions, which can be recycled back into its original components without toxic solvents or intensive lab processes.

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