Sustainable Photochromic Wearables With Excellent Retention and Superior Stability for Customizable Patterns and Information Security Encryption

ABSTRACT Advanced photochromic wearables have aroused growing research interest in customizable pattern display, information security encryption, and intelligent fabrics. Molybdenum trioxide (MoO 3 ), distinguished by its superior photochromic capabilities, has emerged as a prime contender for photochromic wearables among several photochromic materials. However, the advancement of rewritable wearables with MoO 3 is constrained by inadequate adhesion, insufficient stability, and limited scalability. Herein, a fiber‐based photochromic wearable is designed and developed by covalently bonding MoO 3 microcapsules (MM) nanoparticles with a sheath‐core structure into pristine cotton fabrics and integrating MM nanoparticles with sodium alginate (SA) through electrostatic forces and peptide linkages. The resulting photochromic wearable exhibits reversible color transformation and exceptional photochromic characteristics, including remarkable fatigue resistance (>40 cycles), rapid light response, and outstanding color retention (>60 days). Moreover, the photochromic wearable exhibits exceptional stability in diverse harsh environments, including different acid‐base solutions (pH 2.0–9.0), various temperatures (−30°C–60°C), indoor light and sunshine exposure, and repeated laundering (>15 cycles). This photochromic fabric exhibits exceptional wearability, boasting remarkable flexibility (17 mm) and biocompatibility (cell viability >95%). Notably, rewritable T‐shirts and QR code information security encryption systems are demonstrated, highlighting their potential in customizable designs, flexible rewritable textiles, and information security encryption.