Polarization‐Driven Molecular Alignment of Azopolymer for Dual‐Encrypted and Moiré Animation‐Based Anti‐Counterfeiting

• Published in: Advanced functional materials Vol. 35; no. 31
• Main Authors: Chang, Ming‐Hsuan, Dzeng, Yi‐Chung, Chen, Yi‐Ren, Chang, Chun‐Chi, Lee, Lin‐Ruei, Tsai, Tsung‐Hung, Chen, Yi‐Fan, Liu, Yu‐Chun, Sugiyama, Teruki, Chen, Chi, Chen, Jiun‐Tai
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01.08.2025
• Subjects: Alignment; Animation; Authentication; Azo polymers; Composite structures; Counterfeit; Counterfeiting; Encryption; Linear polarization; Moire patterns; Optical microscopy; Polarized light; Security
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202506526

Anti‐counterfeiting technology is crucial for ensuring the authenticity of currency, identification documents, and high‐value products. To address the growing sophistication of counterfeit techniques, a multi‐layered anti‐counterfeiting platform is developed based on an azopolymer (PAzo) system that integrates challenge‐response authentication and physically unclonable function (PUF)‐like characteristics within a unified framework. By leveraging the molecular orientation control of PAzo under linearly polarized light (LPL), encrypted patterns are fabricated that remain invisible under standard conditions and require polarized optical microscopy (POM) for decryption. The fabrication process involves sequential LPL exposures with patterned masks, inducing spatially defined anisotropic molecular alignment, potentially enabling PUF‐like authentication through unique structural variations. To further enhance security, two dynamic anti‐counterfeiting strategies are introduced: 1) dynamic dual pattern anti‐counterfeiting, which encodes multiple polarization‐dependent patterns that appear sequentially under POM as the analyzer is rotated, 2) Moiré pattern animation anti‐counterfeiting, which encodes multiple patterns into a single composite structure that requires a predefined scan pattern for decryption. These multi‐dimensional decryption conditions significantly increase security by introducing both physical and optical constraints. This PAzo‐based approach offers a scalable and adaptive authentication solution, providing enhanced protection against increasingly sophisticated counterfeiting threats.