In many polymer-based materials indispensable to modern life, the elasticity of the material is key. From Lycra clothing to tire rubber, the ability to flex and stretch without being permanently altered is necessary to the functionality, and so too is the materials’ strength. Traditional polymer synthesis techniques increase strength, though they generally make a material more brittle. This month, researchers at the University of California, Santa Barbara published a method to bypass this trade-off.

Their polymers are inspired by the fibers mussels use to attach themselves to rocks, which are incredibly strong and can also repair broken molecular bonds after stress. By adding negatively charged catechol molecules and positive iron ions to a polymer, additional bonds between chains form, increasing the stiffness of a material by up to 1,000 times without compromising its ability to stretch.

The key development was in the application to dry polymers rather than to those created in water, which have low elasticity due to their turgid state.

The research, published in Science, could lead to major improvements in body armor or artificial tendons.