Plastic may be an artificial hodgepodge of organic and synthetic elements, but Geoffrey Coates’ admiration for the material is very real.
“Plastic is amazing, and it makes the world a better place,” said Coates, the Tisch University Professor in the College of Arts and Sciences’ Department of Chemistry and Chemical Biology. “It keeps our food safe. It keeps our cars light and fuel efficient. There are countless ways that plastics improve our lives.”
However, the environmental havoc that plastic can wreak is also very real, and well documented.
Coates is leading a team of Cornell researchers working on the next generation of environment-friendly plastics as part of the NSF Center for Sustainable Polymers, a multi-university collaboration based at the University of Minnesota-Twin Cities Campus that is one of nine Phase II Centers for Chemical Innovation funded by the National Science Foundation. This month, the NSF awarded the center a five-year, $20 million grant renewal.
Joining Coates on the Cornell team is Brett Fors, associate professor of chemistry and chemical biology; Chris Alabi, associate professor and a Nancy and Peter Meinig Family Investigator in the Life Sciences; and Anne LaPointe, senior research associate in chemistry, as well as their postdoctoral and graduate students.
“We have to improve how we make our plastic and control where it goes when we’re done using it,” Coates said. “Every year, we make over 100 pounds of plastic for every person on the planet. About a third of all plastic packaging ends up in the environment. If it falls in the ocean, it’s going to float around for hundreds of years. By 2050, there’s going to be more plastic by weight in the ocean than fish. We must change this.”
Because the manufacture of plastic is an energy-intensive process that often chews up fossil fuels and spits out large amounts of carbon dioxide, the center is working to develop renewable feedstocks that can take the place of fossil fuels. Coates and his collaborators have produced a polymer that combines carbon dioxide and feedstocks called ‘epoxides,’ resulting in a hard plastic, similar to polystyrene, that could potentially replace polyurethanes used in coatings, foams, sealants and adhesives.
“These pellets are almost 50% carbon dioxide,” Coates said. “That is bio-derived carbon dioxide that came from fermenting sugar. You can view that as plants grabbing the carbon dioxide from the atmosphere, converting it to sugar, and we’re using the CO2 formed via its fermentation to make plastic. Overall, we’re using considerably less fossil fuel than is needed to make common plastics.”
The Cornell team is also looking at ways to reduce the environmental impact of plastic products after consumers discard them. Less than 2% of plastic packaging gets recycled, and the two most ubiquitous plastics – polyethylene and polypropylene – must be recycled separately because they have incompatible chemical structures. Since automated and manual sorting can be cost-prohibitive, much of this material ends up in landfills.
Coates and his collaborators consequently developed a multiblock polymer – Coates jokingly refers to it as “magic pixie dust” – that binds polyethylene to polypropylene so they can be recycled together. He and his team are also aiming to design a plastic that behaves like polyethylene, so if such packaging does make its way into the ocean, it will degrade back to carbon dioxide and water rather than drift around for hundreds of years.
“If we don’t fix these problems, there will continue to be – not unreasonably – a public backlash against using plastics,” Coates said. “But then we’ll be driving around in heavy steel cars that use more energy than ever. We’ll have food that spoils and people get sick because we can’t keep our food supply safe. So we have to be responsible and keep the good aspects of plastics while getting rid of the negative attributes.”
Academic partners in the Center for Sustainable Polymers include the University of Minnesota; Northwestern University; the University of California, Berkeley; the University of Chicago; Washington University in St. Louis; and the University of South Dakota.