Begone, ye olde nylon! Novel technology appears for affordable, sustainable Nylon 2.0

February 11, 2016 |

Research-Photo-for-HomepageUsers of car parts, plastic wheels, synthetic rope, fibers, shoes, guitar strings and a host of other everyday applications may be unexpectedly joining the biobased revolution soon, now that engineers at Iowa State University have combined a genetically engineered strain of yeast and an electrocatalyst to affordably convert sugar into a new type of nylon.

Why the big deal? Previous attempts to combine biocatalysis and chemical catalysis to produce renewable chemicals have resulted in low conversion rates. That’s usually because the biological processes leave residual impurities that harm the effectiveness of chemical catalysts.

The science

Zengyi Shao’s Iowa State-based research group has created genetically engineered yeast – “a microbial factory,” she said – that ferments glucose into muconic acid. By applying metabolic engineering strategies, the group also significantly improved the yield of the acid. Then, without any purification, Tessonnier’s group introduced a metal catalyst – lead – into the mixture and applied a small voltage to convert the acid. The resulting reaction adds hydrogen to the mix and produces 3-hexenedioic acid.

Bottom line? After simple separation and polymerization, the engineers produced biobased, unsaturated nylon-6,6, which has the advantage of an extra double bond in its backbone that can be used to tailor the polymer’s properties.

What’s the competitive edge? The reaction is performed at room temperature, it uses a cheap and abundant metal instead of precious elements such as palladium or platinum, and the other compounds involved in the reaction are produced from water.

The engineers’ successful hybrid conversion process is described online and as the cover paper of the Feb. 12 issue of the journal Angewandte Chemie International Edition. You can read more about the science here.

Next steps

The process described by the engineers “opens the door to the production of a broad range of compounds not accessible from the petrochemical industry,” Shao said.

Moving forward, the engineers will work to scale up their technology by developing a continuous conversion process, said Tessonnier, who’s a Carol and Jack Johnson Faculty Fellow and also an associate scientist with the U.S. Department of Energy’s Ames Laboratory.

Reaction from the inventors

“The ideal biorefinery pipelines, from biomass to the final products, are currently disrupted by a gap between biological conversion and chemical diversification. We herein report a strategy to bridge this gap with a hybrid fermentation and electrocatalytic process,” wrote Shao and co-lead Jean-Philippe Tessonnier, Iowa State assistant professors of chemical and biological engineering who are also affiliated with the National Science Foundation Engineering Research Center for Biorenewable Chemicals, based at Iowa State.

“We gave it a try and it worked immediately,” Tessonnier said. “The process does not need additional chemical supplement, and it works amazingly at ambient temperature and pressure, which is very rare for this type of process.”

Validating “the CBIRC way”

While “the CBIRC way” is slightly narrower in scope than, say, “the Iowa Way” or “the American Way” — there’s a vision there. Put simply, it’s about combining the tools of biologists and chemists to develop hybrid technologies that produce novel biorenewable chemicals.

It doesn’t have to be formal — the benefits of collaboration between scientists representing different disciplines. After all, it was fostering such collaboration between scientists at CERN that led computer scientist Tim Berners-Lee to invent the World Wide Web, the technology enabling you to read this article — as a side project.

In this case, Shao and Tessonnier started talking about working together while car-pooling from a research meeting two hours from campus. Little did we know that a shared car can act as a reactor and conversation about the weather and traffic can catalyze a breakthrough in biobased materials.

Innovation, as it turns out, is as dependent on residence time and the reactivity of two minds brought into contact under optimally designed conditions as, well, catalytic conversion itself. So, kudos to CBiRC, the National Science Foundation, Iowa State’s Plant Sciences Institute and the Ames Laboratory, who supported the research.

“CBiRC seeds these new ideas and concepts,” Tessonnier said. “It’s all about integration.”

Additional Iowa State co-authors of the paper are: Miguel Suastegui, a graduate student in chemical and biological engineering who’s also affiliated with CBiRC; John Matthiesen, a graduate student in chemical and biological engineering who’s also affiliated with CBiRC and the Ames Laboratory; Jack Carraher, a postdoctoral research associate in chemical and biological engineering who’s also affiliated with CBiRC; Nacu Hernandez, an associate scientist in chemical and biological engineering; Natalia Rodriguez Quiroz, a research associate for CBiRC; Adam Okerlund, the translational research manager for CBiRC; and Eric Cochran, an associate professor of chemical and biological engineering.

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