Electrospun spiropyran-based photochromic nanofibers with enhanced stability for anti-counterfeiting

A spiropyran-AIEgen integration strategy is proposed to construct multicolor photochromic systems beyond conventional single-color switching. • Electrospinning-enabled polymer encapsulation markedly enhances the stability of spiropyran, yielding high-performance solid-state photochromic nanofibers. • The resulting materials enable multilevel color encryption, offering strong potential for advanced anti-counterfeiting applications. Photochromism has emerged as a promising strategy for enhancing anti-counterfeiting technologies, where the development of materials combining rapid response with high stability remains a critical challenge. Herein, a novel spiropyran-tetraphenylethylene (SP-TPE) photochromic material was designed and successfully synthesized. The material exhibited rapid and reversible photochromic behavior in solution, accompanied by pronounced aggregation-induced luminescence. Owing to this synergistic effect, SP-TPE displayed distinct multicolor photoresponses rather than a conventional single-color transition, significantly expanding the accessible photochromic color space. Cytotoxicity evaluations confirmed its low toxicity and good biocompatibility. To overcome the limited stability of SP-TPE in solution, polymer encapsulation via electrospinning was employed to fabricate nanofibrous films with spatial confinement. The resulting SP-TPE films retained pronounced photochromic performance even at low concentrations and low light intensities, while exhibiting markedly enhanced thermal stability. Under identical conditions, the color recovery time was extended from approximately 30 s in solution to over 800 s in the solid state. Moreover, concentration- and light-intensity-dependent color modulation enabled multilevel color encryption. This work provides an effective strategy for constructing stable, multicolor photochromic systems and offers new insights into the development of advanced spiropyran-based anti-counterfeiting materials. Download: Download high-res image (312KB) Download: Download full-size image