Nylon 6 is a semi-crystalline thermoplastic with a range of uses, especially as a synthetic fiber. First developed to mimic the properties of nylon 6,6, nylon 6 has slightly different mechanical properties and more luster as a fiber (think shiny nylon rope). Nylon 6 is made via a ring opening polymerization from a single monomer (caprolactam).
Polymerization of caprolactam into nylon-6, from Wikipedia
Almost every commercial plastic or polymer is a petrochemical, something that many researchers are working on changing (including many UW system researchers!). This usually means using a plant source to make monomers or other precursors, in order to lessen the reliance on fossil fuels. Even replacing only one monomer from a polymerization could significantly reduce the required fossil fuel inputs. Examples of already commercial bio-based, or made from plants, plastics are poly(lactic acid) (PLA), cellulosic materials, and various polyesters. More difficult to make in a commercially viable manner are some of the common commodity plastics such as polyolefins or polystyrene.
A collaboration between California based company Genomatica and Italian based Aquafil Holding SpA has now successfully completed a demonstration scale production run for plant based nylon-6. Aquafil is a company focusing on plastics and the circular economy, such as chemical recycling of nylon from sources such as discarded carpets. AquafilSLO, an Aquafil subsidiary based in Slovenia, makes the bio-caprolactam and now has demonstrated the polymerization of several tons of this material into a biobased nylon-6. However, to be able to meet growing demand for plastics such as nylon while reducing carbon emissions, strategies other than chemical recycling will be needed. An argument can also be made outside of the environmental one that having another source for caprolactam is a good hedge against supply chain disruptions such as those we so commonly deal with these days.
Next steps include further scale up (Genomatica’s specialty) and finding large brands (especially in the apparel space) that are interested in using bio-based nylon 6.