• • Light fastness improved to Grades 3–4 (ISO 105 B02), enabling stable thermochromic function for several months of sunlight exposure, a significant upgrade from typical Grade 2–3 for unprotected systems.
• • Dual UV-shielding strategy blocks nearly the entire UV spectrum, reducing degradation of thermochromic three-component compounds; maximum decolorization rate controlled within 10% under benzophenone/benzothiazole protection.
• • Coaxial wet-spinning process creates core-sheath structure, minimizing impact on mechanical properties compared to excessive UV absorber dosage, which can compromise fiber wearability.
• • C12-Azo stores absorbed UV energy via trans-to-cis photoisomerization, enabling on-demand heat release, adding functional value beyond mere UV blocking.