Structure‐Guided Dynamical Mechanics in Bioinspired Double Twisted Laminated Thin Films

ABSTRACT

Nature produces unique crafted architectures, containing structures such as hierarchical stacked lamellae, core–shell composites, and helically twisted fibers to create enhanced multimodal mechanical material performance. Specifically, natural laminated architectures are formed from polysaccharides due to their natural abundance and multitude of functionalities such as mechanical stiffness, high aspect ratio, and unique optical polarization. More complex structures such as the double orthogonal twisted stacks exist in specific fish scales, made from collagen fibers, providing increased mechanical toughness. This work presents a dynamic mechanistic study of improved compressive stiffness, elastic recovery, and differing crack propagation mechanisms through double twisted laminated structures created from shear‐aligned layers of cellulose nanocrystals. As observed in real‐time high resolution electron microscopy monitoring, these unique twisted laminated films displayed a tortuous crack propagation pathway under compressive stresses due to the abrupt rotational change between adjacent unidirectionally oriented nanocrystal layers while experiencing complex failure in the form of complementary intralaminar delamination that facilitates higher structural stiffness and enhanced structural recovery after stress release. These results provide insight into how non‐traditional, nature‐inspired helical nanoscale architectures with local twisted nanoscale alignment dictates enhanced mechanical behavior, ideal for damage tolerant thin films and coatings as well as crack‐arresting composite materials.