03. Plastics from Oranges
Geoffrey Coates, Chemistry and Chemical Biology, and his graduate students discovered how to make polymers using limonene oxide and carbon dioxide as building blocks with the help of a catalyst developed in his laboratory. Limonene is a carbon-based compound produced in more than 300 plant species, and it makes up 95 percent of the oil in the peel of oranges. In industry, the orange peel oil is extracted for various uses, such as giving household cleaners a citrus scent. The oil can be oxidized to create limonene oxide. Using Coates’ catalyst to combine the limonene oxide and carbon dioxide, a waste product, the researchers produced a new polymer—polylimonene carbonate—that has many of the characteristics of polystyrene, a petroleum-based plastic currently used to make many disposable plastics products. Petroleum is used as a building block for nearly all plastics from polyester in clothing to plastics used for food packaging and electronics. A plastic with favorable qualities made using readily abundant and completely renewable, cheap resources will be highly beneficial and necessary for the future.