Biopolymers: shape memory in spider draglines.
The ductility and strength of spider draglines means that they outperform the best synthetic fibres, but surprisingly little is known about the torsional properties of this remarkable filament. Unlike a mountain climber swinging from a rope, a spider suspended from its silk thread hardly ever twists. Here we show that a spider dragline has a torsional shape 'memory' in that it can reversibly and totally recover its initial form without any external stimulus; its observed relaxation dynamics indicate that these biological molecules have successively different torsional constants.
Emile
Olivier
O
Laboratoire de Physique des Lasers, UMR CNRS 6627, Université de Rennes 1, 35042 Rennes, France. olivier.emile@univ-rennes1.fr
Le Floch
Albert
A
Vollrath
Fritz
F
D000818:Animals; D001696:Biomechanical Phenomena; D001704:Biopolymers / Q000737:chemistry; D003300:Copper / Q000737:chemistry; D047011:Silk / Q000737:chemistry* / Q000648:ultrastructure; D013112:Spiders / Q000737:chemistry* / Q000502:physiology*; D019415:Torque; D014102:Torsion Abnormality
D001704:Biopolymers; D047011:Silk; D003300:Copper