Amorphous–Crystalline Solid Transformation-Induced Self-Actuation of Bending-to-Straightening Behavior via Helical Deformation

Bending-to-straightening behavior is vital for both natural processes and advanced materials design. Nonclassical crystallization pathways, particularly amorphous-crystalline transformations, offer opportunities to achieve such dynamic actuation. This study reveals that sugar azides are capable of undergoing spontaneous bending-to-straightening behavior, accompanied by helical deformation, driven by an amorphous-crystalline transformation during anisotropic self-assembly. The process is initiated with bending amorphous nanowires, which evolve into locally crystallized twisted nanoribbons and ultimately straighten into crystalline rectangular hollow tubes through screw dislocation. This transformation is governed by the interplay between the stereostructure of the sugar backbone and the collinear dipole arrangement of the azide group, which together regulates initial helical aggregation and subsequent directional growth. These findings not only clarify the molecular origins of bending-to-straightening crystallization but also provide a strategy for designing responsive materials capable of adapting to unstructured environments.