The next time you bungee jump off a cliff, new materials developed in the United States and Canada may be able to provide you with a smoother ride.
Based on mermaid's necklace, a gooey, stringy material snails use to protect their growing embryos, the synthetic substance could have a range of applications, from bounce-less bungee cords to replacement, artificial ligaments for knees and other joints.
“These delicate little critters are tossed around for months and months by very large breakers and manage to survive,” said Herbert Waite, a professor at the University of California, Santa Barbara, and co-author of a new paper in the journal Nature Materials who is studying the mermaid’s necklace.
“You could put something that delicate in a leather or plastic pouch, subject it to that same environment, and it would be very damaged.”
Similar to DNA
Washed up on the beach, mermaid's necklace resembles a translucent, gooey string of pearls several feet long.
At the molecular level, mermaid's necklace resembles a twisted ladder, similar to DNA, but with three stringers instead of two.
As the twisted triple helix emerges from the whelk, a snail found on the East Coast of the United States, the creature layers the strands on top of each other, forming a small, tube-shaped casing. The 50 to 100 strands give the necklace the strength of plastic and the flexibility of rubber.
Pulled in opposite directions, mermaid's necklace stretches like a rubber band, the bonds between the coiled triple helices breaking one by one as the material elongates.
Unlike a rubber band, however, once the maximum length is reached, mermaid's necklace doesn't quickly bounce back. The triple helices slowly re-form the broken bonds, shortening the strand back to its original resting length.