01/17/2005: 
Technologica
Sweet and environmentally beneficial discovery: Plastics made from orange peel and a greenhouse gas
from Cornell News
A Cornell University research group has made a sweet and environmentally beneficial discovery -- how to make plastics from citrus fruits, such as oranges, and carbon dioxide.
In a paper published in a recent issue of the Journal of the American Chemical Society (Sept. 2004), Geoffrey Coates, a Cornell professor of chemistry and chemical biology, and his graduate students Chris Byrne and Scott Allen describe a way to make polymers using limonene oxide and carbon dioxide, with the help of a novel "helper molecule" -- a catalyst developed in the researchers' laboratory.
Limonene is a carbon-based compound produced in more than 300 plant species. In oranges it makes up about 95 percent of the oil in the peel.
The other building block they used was carbon dioxide (CO2), an atmospheric gas that has been rising steadily over the past century and a half -- due largely to the combustion of fossil fuels -- becoming an environmentally harmful greenhouse gas.
By using their catalyst to combine the limonene oxide and CO2, the Coates group produced a novel polymer -- called polylimonene carbonate -- that has many of the characteristics of polystyrene, a petroleum-based plastic currently used to make many disposable plastic products.
"Almost every plastic out there, from the polyester in clothing to the plastics used for food packaging and electronics, goes back to the use of petroleum as a building block," Coates observes. "If you can get away from using oil and instead use readily abundant, renewable and cheap resources, then that's something we need to investigate. What's exciting about this work is that from completely renewable resources, we were able to make a plastic with very nice qualities."
For more information, check out the website of the Coates Research Group.
