Kinetic Self-Assembly of Hierarchical V-Notch Spherulites via Asynchronous Polymerization-Crystallization for Multiscale Anticounterfeiting

The controlled self-assembly of anisotropic spherulites has long represented a significant challenge, primarily due to the thermodynamic favorability of isotropic structures and the transient nature of crystallization intermediates. In this work, we present a conceptual advance in polymerization-induced crystallization-driven self-assembly (PI-CDSA) by strategically harnessing the kinetic asynchrony between polymerization and crystallization to direct the formation of anisotropic spherulites. Through a bulk PI-CDSA (BPI-CDSA) protocol conducted at a low temperature (10 °C), we achieved precise control over the self-assembly of 3D hierarchical anisotropic spherulites featuring well-defined V-notch defects from a semicrystalline poly(δ-valerolactone) (PVL). This methodology leverages the steric hindrance effect of solvated block and secondary crystallization of the supersaturated PVL block under supercooling conditions, thereby revealing a nonequilibrium self-assembly pathway for V-notch spherulites via critical metastable intermediates, such as nanorods, hedrites, dendritic sheaves, and "two-eyed" spherulites. The asynchronous kinetics, characterized by crystallization lagging behind polymerization, were unequivocally confirmed through in situ solid-state NMR and wide-angle X-ray scattering analyses. By capitalizing on the distinct morphological architecture, we successfully engineered V-notch spherulites as functional structural motifs onto cellulose fibers, enabling a specialty paper with robust multiscale anticounterfeiting capabilities. This work not only establishes a kinetic-control paradigm for nonequilibrium self-assembly, but also opens avenues to advanced materials through defect-guided engineering.