Lee Lin-Ruei, Chen Yi-Fan, Fan Po-Xin, Lin Yu-Chun, Chang Ming-Hsuan, Liu Yu-Chun, Chang Chun-Chi, Chen Jiun-Tai
Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu, 300093, Taiwan.
Center for Emergent Functional Matter Science, National Yang Ming Chiao Tung University, Hsinchu, 300093, Taiwan.
Small. 2025 Sep;21(37):e07008. doi: 10.1002/smll.202507008. Epub 2025 Aug 4.
A dual-stimuli chromogenic platform based on spiropyran-functionalized anodic aluminum oxide (SP-t-AAO) membranes with reversible photochromic and halochromic switching is reported. Surface characterization by electronic images confirms the well-preserved nanoporous morphology, while Energy-dispersive X-ray spectroscopy (EDS) scans reveal uniform grafting to micrometer depths. Grazing incidence X-ray photoelectron spectroscopy (GIXPS) and time-of-flight secondary ion mass Spectrometry (TOF-SIMS) further confirm successful surface chemical modification and pattern fidelity. Orthogonal functionalization is achieved via thiol-yne chemistry and spatially controlled photopatterning using Chinese seasonal-themed photomasks. Upon UV irradiation, the membrane exhibits a pale-to-magenta color change because of spiropyran-merocyanine isomerization; acid exposure further switches the color from magenta to yellow. Both transitions are fully reversible under white light or base treatment. Video analysis reveals rapid halochromic switching kinetics (0.4-4 s), highlighting excellent optical responsiveness. The membrane also demonstrates the chelation toward heavy metal ions such as Cu and Fe. Moreover, thermal cycling test shows moderate durability, and a 20-day ambient test confirms excellent chromogenic stability. This work offers high-speed responsiveness, spatial precision, and long-term stability for anti-counterfeiting and sensing applications.
