Tailoring Intermolecular Interactions in Spiropyran-Functionalized Anodic Aluminum Oxide for Dual-Mode Optical Switching and Dynamic Anti-Counterfeiting Displays

Anticounterfeiting technologies play a critical role in ensuring product authenticity and security; however, conventional labels often rely on static visual cues that are easily duplicated. Stimuli-responsive materials capable of reversible optical switching provide a promising solution for developing dynamic security platforms. In this study, we construct photo- and thermoresponsive anticounterfeiting systems by covalently grafted spiropyran molecules onto anodic aluminum oxide (AAO) membranes through a UV-initiated thiol–ene click reaction to construct. The nanoporous AAO structure offers a high surface area for uniform functionalization, yielding spiropyran-modified membranes that exhibit rapid and reversible color transition between colorless and reddish-orange states under alternating UV and visible light. Grazing incidence X-ray photoelectron spectroscopy (GIXPS) and time-of-flight secondary ion mass spectrometry (TOF-SIMS) analyses confirm the successful covalent immobilization of spiropyran, while the incorporation of 1-decene spacers mitigates intermolecular aggregation and enhances reusability during repeated switching cycles. Photomask-assisted fabrication further enables programmable pattern generation, producing irreversible, reversible, and real-time optical responses. This strategy integrates multistimuli responsiveness, pattern flexibility, and structural robustness, offering a versatile platform for advanced anticounterfeiting applications.