Iowa State University engineers have developed a type of nylon that is bio-based and renewable. The team says it has overcome the typical problem of low conversion rates when combining biocatalysis and chemical catalysis, namely, residual impurities that damage effectiveness of the chemical catalysts. Their approach overcomes the “gap” between biological conversion and chemical diversification with a hybrid fermentation and electrocatalytic process.

Zengyi Shao and Jean-Philippe Tessonnier produced a bio-based nylon. Image source: Christopher Gannon/Iowa State UniversityGenetically engineered yeast was developed, creating a “microbial factory.” The yeast ferments glucose into muconic acid. Lead is introduced to the mixture and a voltage is applied to convert the acid. A reaction occurs, which adds hydrogen to the mix, producing 3-hexenedioic acid. The next step is a separation and polymerization that results in bio-based, unsaturated nylon 6-6. The material has an extra double bond in its backbone which can be used to customize the material’s mechanical properties.

The researchers say the hybrid conversion process is inexpensive and uses common metals such as lead, rather than more expensive palladium or platinum. The reaction occurs at room temperature and the only other compounds needed are produced from water.

The next phase of their research will be to scale up the technology and develop a continuous conversion process. The researchers say they believe the new process opens the door to “production of a broad range of compounds not accessible from the petrochemical industry.” The team is affiliated with the National Science Foundation Engineering Research Center for Biorenewable Chemicals (CBiRC) at Iowa State University.