Twisting Lamellae Triggering Circular Polarized Luminescence of Chromophoric Moieties in Banded Spherulites With Evolution of Homochirality

Spiropyran‐labeled poly( L ‐lactide) (SP‐PLLA) and poly( D ‐lactide) (SP‐PDLA) were engineered to elucidate how hierarchical chiral polymer morphologies regulate photoisomerization, fluorescence, and circularly polarized luminescence (CPL). The spiropyran chromophore was incorporated as a photoresponsive molecular probe, whereas the enantiomeric polylactide matrices furnished crystallizable chiral scaffolds capable of amplifying supramolecular chirality. Specimens obtained via isothermal annealing developed densely packed crystalline architectures that strongly constrained the reversible interconversion between the spiropyran and merocyanine forms, thereby yielding weak fluorescence and CPL‐inactive (CPL‐silent) behavior. In contrast, solvent annealing in dichloromethane produced banded spherulitic superstructures with a more favorable chain organization, enabling efficient spiropyran photoisomerization in the post‐crystallization state. Pronounced, mutually symmetric CPL signals of opposite sign were detected from the solvent‐annealed PLLA and PDLA banded spherulites, evidencing effective transfer of chirality from the polymeric crystalline morphology to the merocyanine species. Comparative analysis of amorphous, non‐banded spherulitic, and banded spherulitic samples further established that only the banded spherulitic morphology is capable of generating detectable CPL. Collectively, these findings underscore the decisive influence of crystalline packing and hierarchical chiral organization in the design of CPL‐active, photoresponsive polymeric materials.