Polymeric fibers with tunable properties: Lessons from spider silk

Abstract

Making artificial fibers inspired in spider silks is considered as one of the milestones in the field of biomimetics. The interest is usually justified by the outstanding tensile properties of natural fibers, but it is usually overlooked that spider silk is endowed with a number of related properties -supercontraction, recovery and the existence of a ground state -that impart the material with additional desirable features, such as the possibility of tuning its mechanical behaviour. In this work we present a review on the experimental Kevwordsanalysis and significance of these properties, stressing the contributions of our research group to the field. It is Spider silk a ' s0 demonstrated how the knowledge gained in the basic study of the natural material has been essential for Supercontraction the improvement of the properties exhibited by artificially processed bio-inspired silk fibers. Regenerated silk

Emergence of supercontraction in regenerated silkworm (Bombyx mori) silk fibers

“…Initially, the term supercontraction was used to refer to the significant reduction of its length when the fiber is immersed in water with at least one of the ends unrestrained 11 . It was later realized that the shrinkage of the fiber is simply the most evident effect of a much more profound property of the material: the existence of a ground state to which the fiber can revert independently from its loading history by immersion in water 12,13 . The existence of such a ground state implies that the fiber can be stretched following an arbitrary sequence of loads, but it will recover the tensile behaviour of this ground state by being simply allowed to contract in water.…”

Spider silk as a blueprint for greener materials: a review

“…Therefore, the "maximum supercontracted state" can be viewed as a ground (reference) state for silk where the chains are minimally aligned and constrained. [126][127][128] The amplitude of supercontraction depends on the type of silk and spider species. For example, the maximum supercontraction of B. mori fiber is 3%, 129 that of the moth Antheraea Pernyi is 5% 130 while minor ampullate silk do not shrink at all.…”

Self-recovering caddisfly silk: energy dissipating, Ca2+-dependent, double dynamic network fibers

“…Recovery of initial mechanical properties of these plastically deformed materials require reprocessing-a cycle of wetting and drying in the case of spider silks. 10 In contrast, spontaneous re-tensioning and yield domain recovery enables caddisy silk to go through repeated cycles of energy dissipation in its natural watery environment. Self-tensioning repairs the silk composite structures with minimal metabolic investment in reprocessing and reconstruction.…”

“…Examples are polycarbonates used in bullet proof glass and spider web silks, both of which yield and plastically deform to absorb and dissipate kinetic energy to bring ballistic objects to a stop with minimized recoil. 9,10 These materials are single use because most of the post-yield deformation is permanent. Recovery of initial mechanical properties of these plastically deformed materials require reprocessing-a cycle of wetting and drying in the case of spider silks.…”