Corn feeds, powers and even clothes people. Since 2009, the University of Minnesota-based Center for Sustainable Polymers (CSP) has investigated how chemistry can turn renewable feedstocks, such as corn, into plastic and other useful materials.
Given the potential environmental and economic benefits of corn-derived products, Minnesota Corn has invested in CSP research since 2014. In 2022, Minnesota Corn has allocated over $480,000 for seven CSP research projects. All are scheduled to run through early 2024.
As Minnesota Corn enters its fourth year of supporting the current slate of CSP research projects, grower-leaders say they're looking forward to seeing the results.
"It's super exciting to get in another space with the Center for Sustainable Polymers. We are finding out the different ways that corn can be used, and each new research project leads to new ideas," Minnesota Corn Research & Promotion Council Chair Brandon Fast said. "It's exciting to see how we as corn farmers can help the environment and, at the same time, help to have a bigger corn grind, which improves the economics of farming."
Why corn?
Polymers, which are long chains of identical molecules, are the main components of clothing, food packaging, paper and many other products. Some, such as cotton and wool, are derived from natural sources. Many others, such as plastic and nylon, are synthetic and typically derived from petroleum sources.
Using corn instead of petroleum to make synthetic polymers can remake the lifecycle of plastics in very beneficial ways. For example, many corn-based polymers can be manufactured to be compostable. Rather than generating vast rafts of plastic bottles that swirl in the currents of the Pacific Ocean, bioplastic can be gathered and delivered to industrial facilities. The facilities compost the bioplastic using heat and pressure under humid, hot conditions, breaking it down into water, carbon dioxide and biomass.
"We want renewable carbon, bio-based carbon, and it's up to us to figure out how to convert those molecules in interesting, convenient and efficient ways," said Marc Hillmyer, director of CSP, and the principal investigator of the Minnesota Corn-supported projects.
In 2022, the Minnesota Corn-funded CSP research projects break down into several broad categories: improving existing corn-derived polymers like PLA plastic, developing new corn-derived polymers and laying the groundwork for future renewable polymers. Below is a brief overview of the research projects in each category.
Improving PLA plastic Scientists have come to a consensus that the future health of the planet depends on becoming carbon neutral. For that reason, reducing petroleum use tops the agenda.
Since the beginning, one focus of CSP has been to improve a very useful plastic called polylactic acid, also known as polylactide or PLA. The plastic is produced through a process of fermenting corn sugar. NatureWorks, a company formed by Cargill, has manufactured a corn-based plastic called Ingeo PLA for the past two decades.
Three CSP research projects focus on making PLA tougher and more impact resistant, without interfering with its compostability. That makes the plastic useful in a broader array of applications. Films for food packaging and heavy-duty packaging that can protect products like consumer electronics are among the many markets for a tougher PLA.
"PLA is a wonderful polymer," Hillmyer said. "It's got this nice lifecycle; it's from corn, and it's industrially compostable. It comes from the earth and goes back to the earth. That's decidedly different than non-degradable, petroleum-based products like polystyrene."
Another useful part of the corn kernel is oil. CSP scientists are investigating the use of new catalytic chemistries to convert corn oils into new polymeric products.
"We are in discovery mode," Hillmyer said. "This is fundamental research that is trying to chart uncharted territory. Can we get new products, discover new types of polymers, by taking the modern tools of chemistry and applying them to a corn-based feedstock. These are metal-based catalysts, added in small amounts, that lower the barriers to do the chemistries. You might try putting together A plus B, and at room temperature, nothing really happens, but if you add the catalyst, you can get them to go. You add small amounts of catalyst and get a huge effect on the rate of chemical conversions. That is the power of catalysis."
CSP is also exploring how the lignin found in the leafy parts and stalks of the corn plant might be used to create a bio-based nylon-like material. Nylon is in a category of polymers known as polyamides, which have a variety of uses in clothing and textile manufacturing. Here, too, a leading question would be whether bio-based polyamides could be made in such a way as to be both useful and biodegradable.
Another molecule of interest to scientists at CSP is called furan. CSP researchers plan on looking into an array of processes to see what new and valuable uses can be found for corn-based furans.
CSP is also working with chemicals known as weak solid acids, and, in particular, zeolites. These chemicals typically have been used to manipulate petroleum-based molecules, which don't have a lot of oxygen in them, according to Hillmyer. Bio-based molecules, on the other hand, contain abundant oxygen atoms.
"Understanding how these catalysts work with these new kinds of feedstocks is really important," Hillmyer said.
Solid-acid catalysis is one of the chemistries practiced on an industrial scale in the petroleum-refining industry. Discovering how weak solid acids transform oxygenated bio-based molecules could render very valuable replacements, or new uses entirely, depending on what this basic scientific research reveals.
In addition to discovering new polymers, CSP also focuses on developing the next generation of talented scientists who will join the sustainable materials field and carry it on into the future. With support from Minnesota Corn, CSP offers a summer program called the Green and Sustainable Chemistry High School Teachers Workshop. To date, more than 70 teachers have come to the CSP labs and worked with CSP scientists to gain experiences and obtain course materials and lessons they can offer their students. Thousands of high school students have been introduced to 'green chemistry' this way.
To learn more about the Center for Sustainable Polymers and its research, visit csp.umn.edu. Learn more on the Minnesota Corn podcast discussing CSP research at https://bit.ly/3sqza8l.
Categories: Minnesota, Crops, Corn