Strong and tough synthetic yarn

While the humble spider has no trouble spinning silk that’s both strong and tough, makers of synthetic fibers have found there’s usually a trade-off between these two properties. If a material is strong—that is, it resists deformation—usually it lacks toughness, making it prone to fracture, and vice versa. By combining chemical and physical approaches, a team led by the University of Bayreuth’s Andreas Greiner has managed to make polymer yarns that have properties on par with those of spider silk (Science 2019, DOI: 10.1126/science.aay9033). To achieve the combination of strength and toughness, the researchers electrospun poly(acrylonitrile-co-methyl acrylate) yarns with a small amount of poly(ethylene glycol) bisazide—a linking molecule. They then heat stretched the yarns and allowed them to cool under tension. This process aligns the fibers in the yarns and covalently links them to one another via a so-called click reaction (shown). “This underlying principle can be used to create similar strong and tough fibers from other commodity polymers in the future,” the researchers write, “and can be used in a variety of applications in areas such as biomedicine, satellite technology, textiles, aircrafts, and automobiles.”