Mar. 13, 2012
Silk from spider and silkworm shows exceptional mechanical strength, toughness and extensibility if compared to man-made fibers. Other amazing properties are the occurrence of reversible cyclic contraction as well as of permanent super-contraction in fibroin nanofibers electrospun from regenerated Bombyx mori silk. We discovered the key role of the metastable silk-I modification and of the non-crystalline regions with oriented chains in the cyclic behavior under restrained conditions, and the role the silk-II ß-crystallinity plays in super-contraction.