From micro to macro: Unraveling the origin of the counterintuitive response in spider silk fibers

Abstract: Spider silk is an extraordinary protein material characterized by high strength and toughness. Upon exposure to high humidity, silk fibers experience a reduction in stiffness of several orders of magnitude, supercontraction (i.e., a shortening of up to ~60% in length), and twist. These counterintuitive responses originate from a unique polymeric structure made of crystalline domains that are embedded in a highly aligned amorphous matrix. Broadly, high humidity leads to water uptake by the silk, which in turn motivates the dissociation of intermolecular hydrogen cross-linking bonds. In this talk, I will present energetically motivated models based on tools from statistical mechanics that shed light on the relations between the microstructure and the macroscopic behavior and capture the overall response of silk fibers. The models are validated through a comparison to experimental findings. The insights from these models provide a method to characterize the microstructural evolution of hydrogen-bond dominated networks and pave the way to the design of novel biomimetic fibers with non-trivial properties.

1) R. Olive and N. Cohen, “Deformation and failure mechanisms in spider silk fibers”, Journal of the Mechanics and Physics of Solids, 182:105480, 2024.

2) N. Cohen, “The underlying mechanisms behind the hydration-induced and mechanical response of spider silk”, Journal of the Mechanics and Physics of Solids, 172:105141, 2023.

3) N. Cohen and C.D. Eisenbach, “Humidity-Driven Supercontraction and Twist in Spider Silk”, Physical Review Letters, 128:098101, 2022.

4) N. Cohen, M. Levin, and C.D. Eisenbach, “On the origin of supercontraction in spider silk”, Biomacromolecules, 22:993-1000, 2021.

MathematicsPhysics

Audience: researchers in the topic

Comments: Please note the time and location change for this talk !!!

---

Nečas Seminar on Continuum Mechanics

Series comments: This seminar was founded on December 14, 1966.

Faculty of Mathematics and Physics, Charles University, Sokolovská 83, Prague 8. If not written otherwise, we will meet on Mondays at 15:40 in lecture hall K3 (2nd floor)

---