Abstract:

Objective In response to the problems of weak dynamic response capability and insufficient security of traditional anti-counterfeiting technologies, this study aims to develop a new type of photochromic textile and construct a high-security dynamic authentication system suitable for smart textiles.

Method Highly stable photochromic ink was prepared by constructing a nitrobenzopyrylospiran-poly methyl methacrylate mixed solvent system. Polyester yarns of 16.67 tex were immersed, padded with 70% wet pickup, dried at 50 ℃ for 30 min, before being woven into plain fabrics. To enhance the recognizability of the anti-counterfeiting Quick Response (QR) codes, the same treated polyester yarns were used to embroider the QR codes onto the plain fabrics that were woven from the untreated polyester yarns. Characterization involved chemical structure, optical properties, air permeability testing, friction and light fastness evaluation, contact angle measurement, and ultraviolet illumination-response trials using a 365 nm lamp.

Results The photochromic textile exhibited exceptional responsiveness, achieving visible coloration within 1 s under 365 nm ultraviolet irradiation and complete decoloration within 2 min after light removal, demonstrating excellent reversibility across multiple cycles. Analysis using Fourier Transform Infrared Spectroscopy, confirmed successful ink fixation via hydrogen bonding evidenced by a broad peak near 3 300 cm^-1, aromatic C—H interactions appearing at 3 030 cm^-1, and potential C—N bond formation indicated by a shoulder peak around 1 180 cm^-1. Ultraviolet-Visible spectroscopy revealed that ultraviolet exposure induced a prominent absorption band at 500 nm, corresponding to a transition from white coloration to rose-red. Before irradiation, the fabric exhibited high reflectivity across 400-700 nm with CIE Lab parameters showing L^* near 100 and a^* and b^* close to zero, yielding RGB values of 235, 232, 223. After ultraviolet exposure, L^* decreased significantly while a^* rose to approximately +54 and b^* turned negative, producing RGB values of 146, 99, 141, characteristic of rose-red hues. The average air permeability of the fabric reached 145.57 mm/s with a coefficient of variation of only 6.39%, indicating uniform structure and satisfactory wearing comfort. Color fastness testing yielded ratings of 4 to 5 for both dry and wet rubbing resistance, and 3 to 4 for light fastness, confirming adequate durability for indoor applications. Continuous 12 h xenon lamp exposure demonstrated gradual absorbance decay under illumination while baseline absorbance remained stable, indicating irreversible photo-oxidation of photochromic molecules without substrate degradation, consistent with the observed light fastness rating. The textile exhibited robust hydrophobicity, with contact angles all exceeding 90° over 3 s. For anti-counterfeiting functionality, the embroidered QR code remained machine-readable only during a narrow 30 s window after ultraviolet removal, becoming undetectable within 2 min as color faded spontaneously.

Conclusion This photochromic textile system constitutes a robust platform for advanced dynamic anti-counterfeiting applications, integrating rapid optical responsivity, mechanical durability, and superior hydrophobicity. The dual-mode authentication mechanism with its narrow temporal window and non-replicable fading behavior substantially enhances security compared to static identifiers. Future research should focus on improving long-term photostability through molecular engineering, developing multi-dimensional encryption protocols, and optimizing industrial-scale inkjet printing for precise color kinetic control. This work establishes a viable technological pathway for implementing intelligent, traceable anti-counterfeiting solutions in smart wearable textiles and high-value product authentication, offering significant potential for integration with blockchain-based traceability systems.

Key words: photochromic material, intelligent textiles, anti-counterfeiting technology, functional textiles, ultraviolet light response, anti-counterfeiting ink, anti-counterfeiting QR code, anti-counterfeiting textiles