Like all plastics, the new material is a polymer—a large molecule comprising smaller, repeating units called monomers. The monomer itself is relatively new. The units are called omega-hydroxyfatty acids, and when strung together to form a polymer, they can produce a biologically friendly plastic. Until now, omega-hydroxyfatty acids were difficult and expensive to produce using traditional methods, prohibiting their widespread use.

Gross produced the monomer in a first-of-its-kind fermentation process, a fairly quick, low-cost method. The monomer is then polymerized to form a uniquely ductile, strong natural plastic that biodegrades completely in soil.

Gross and his team devised a new way to produce these monomers by using a genetically modified strain of the yeast Candida tropicalis. The engineered yeast is capable of converting fatty acids of plant oils into large quantities of omega-hydroxyfatty acids. When polymerized, the new material may be a suitable substitute for petroleum derived plastics such as polyethylene for uses such as disposable gloves, multilayer food packaging films, and films for ice, trash, garments, produce bags and more.

This is a very exciting development in the field, and not just because we’ve created a bioplastic with desirable properties. This process uses no fossil fuels, and every step is biologically-friendly, from fatty acids in plant oils through the end product, which is a versatile, 100 percent biodegradable plastic.

—Richard Gross

The new bioplastic is highly resistant to moisture, which is an important improvement over currently sold bioplastics such as polylactic acid and starch-based plastics.

Gross’ company, SyntheZyme, was tapped by the US Defense Advanced Research Projects Agency (DARPA) to develop this bioplastic. The material was originally intended to serve a dual purpose: as packaging material in the solid state, and as a biodiesel for military engines after being broken back down or de-polymerized to monomer units.

The material development and performance in the solid state has been successfully completed; research into converting the plastic to diesel is currently under way.

Resources

• Wenhua Lu, Jon E. Ness, Wenchun Xie, Xiaoyan Zhang, Jeremy Minshull, Richard A. Gross (2010) Biosynthesis of Monomers for Plastics from Renewable Oils. Journal of the American Chemical Society 132 (43), 15451-15455 doi: 10.1021/ja107707v