A biobased polymer for greener glue

Naturally produced by bacteria, polyhydroxyalkanoates (PHAs) such as poly(3-hydroxybutyrate) (P3HB) have been attracting attention as potentially greener alternatives to plastics like polyethylene and polypropylene. And polymer chemist Eugene Chen of Colorado State University thinks that, with some careful engineering, P3HB could replace even more plastics. “There are an astronomical number of possibilities,” Chen says. “The design space is very, very vast.” Like polypropylene, P3HB has methyl groups poking off its polymer backbone. The form of P3HB that’s made by bacteria has all its methyl groups aligned in the same direction. This results in a strong, stiff, brittle material. But altering the stereochemistry makes it possible to unlock new properties, Chen says. His group teamed up with chemical engineer Ting Xu of the University of California, Berkeley, and Gregg Beckham of the National Renewable Energy Laboratory to figure out just the right stereochemical arrangement to make P3HB into a strong yet