Photogenerated fluphenazine radical cations for antiviral functionalization of polypropylene masks

Abstract The incorporation of photoactive molecules into polymeric substrates offers a compelling route to introduce advanced functionality while preserving the host material's intrinsic properties. In this study, we investigate a light‐driven strategy for functionalizing polypropylene (PP) nonwoven masks with fluphenazine, a phenothiazine derivative with well‐established photoredox activity. Upon irradiation in aqueous media, fluphenazine undergoes photoinduced transformations that enable its interaction and stabilization at the polymer surface, generating a distinct photoactive interface. The functionalized PP materials exhibit a pronounced response when challenged under biologically relevant conditions, indicating that the photoinduced species play a key role at the polymer–environment interface. Structural analysis by X‐ray diffraction combined with Rietveld refinement reveals that this functionalization approach does not disrupt the semicrystalline morphology of PP. The crystalline phase composition and lattice parameters are preserved, with only subtle nanoscale variations, suggesting interfacial effects rather than bulk structural modification. Extending the analysis to cellulose‐based textiles reveals comparable structural trends, pointing to a general interaction pattern between phenothiazine‐based photoactive molecules and polymeric substrates of distinct chemical natures. Together, these results highlight how photoinduced functionalization can modify surface‐related properties of polymers while maintaining their structural integrity, offering new insights into structure–property relationships in photoactive polymer systems and a versatile platform for the design of advanced functional nonwoven materials. © 2026 The Author(s). Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.