Melanin may boost strength of foams and fabrics

Creating stronger materials may be as simple as adding melanin, the molecule that lends skin its pigment and protects animals from ultraviolet rays.

In recent experiments, scientists found a small addition of melanin made polyurethane much stronger. Researchers described their findings in the journal Biomacromolecules.

Polyurethane mostly comes in the form of high-resistance foam, used most commonly for seating and insulation. But the material is used to enhance a variety of products, from epoxies to clothes.

Materials scientists have traded a range of additives and fillers in an attempt to bolster polyurethane, but gains have been modest and often isolated to singular physical qualities -- improving either tensile strength or toughness, but not both.

A material's tensile strength is its resistance to breaking under tension. Toughness describes a material's ability to absorb energy without breaking.

Experiments showed polyurethane samples containing just 2 percent melanin -- sourced from the ink sacs of cuttlefish -- were tougher and more resistant to tension than control materials.