A phenomenological theory for hydration-induced supercontraction and twist of spider dragline silk

Spider dragline silk is one promising material for producing artificial muscles, owing to its remarkable capacity for supercontraction and twist when exposed to high humidity. Based on the hydration absorption equation and the standard reinforcing model, we develop a phenomenological theory for elucidating the hydration-induced supercontraction and twist of spider dragline silk. The theory can reasonably predict the responses of softening, anisotropy, hydration-supercontraction, and twist of spider dragline silk. The theoretical predictions align with the experimental results. This study provides valuable insight into the underlying mechanisms of the hydration-induced deformation of spider dragline silk.