Dual-Mode Optical Nanocomposite Filaments for Smart Textiles: Synergistic Integration of Interference Color and Luminescent Emission

While smart textiles promise transformative functionality, their predominant reliance on synthetic polymers continues to pose environmental challenges. Biobased nanocellulose emerges as a promising sustainable alternative, exhibiting intrinsic birefringence, stimulus responsiveness, and versatile compositing capabilities for personalized textile design. Herein, we report durable photonic filaments prepared by photopolymerizing cellulose nanocrystals (CNCs) embedded in a poly(ethylene glycol) diacrylate (PEGDA) matrix. The resulting filaments produce dual optical signals: bright luminescence originating from aggregation-induced emission of PEGDA monomers, and pressure-responsive interference color variations stemming from highly aligned CNC arrangements. The filaments maintain stable luminescent emission after exposure to acid, base, washing, and freeze–thaw cycles. Furthermore, they exhibit high tensile strength (up to 42 MPa), exceptional fatigue resistance, flexibility, stitchability, and embroidery compatibility, enabling seamless integration into textiles without functionality loss. This approach and the multifunctional filaments advance the development of sustainable, aesthetically adaptive textiles for smart wearables and other applications requiring dynamic optical responses.