Programmable Thermochromic Coatings via Interfacial Phase Fusion‐Separation Engineering

Thermoresponsive structural color materials hold great promise for dynamic anti-counterfeiting and thermal monitoring, yet their widespread adoption is hindered by complex self-assembly processes and limited scalability. Here, an innovative interfacial fusion-separation mechanism is proposed for programmable thermochromic coatings (HPTCs), achieved by blending independently chromogenic hollow silica (H-SiO₂) photonic nanopigments with eutectic phase change material (EPCM). This design circumvents traditional self-assembly requirements while enabling commercially viable spray-coating fabrication. Meanwhile, these HPTCs exhibit tunable transition thresholds rapid color switching (4 s) and exceptional cycling stability (>500 cycles) within a narrow physiological temperature window (33-37 °C), driven by EPCM solid-liquid transitions modulating refractive-index contrast. A sandwich-like process, comprising waterborne acrylic (WA) adhesive, H-SiO₂-EPCM functional, and WA protective layers, simultaneously ensures mechanical robustness and substrate versatility. The self-assembly-free design enables standalone anticounterfeiting labels with programmable color patterns for interactive authentication. Furthermore, the fusion-separation-driven thermochromic mechanism enables programmable tuning of response temperatures via fatty acid selection, allowing integration of multiple HPTCs into a versatile real-time temperature indicator for personalized health monitoring, drinking-water temperature warning, and electronic thermal risk detection. This interfacial engineering strategy simplifies fabrication of stimuli-responsive optical materials, demonstrating significant potential for scalable manufacturing of commercial anticounterfeiting labels and the temperature indicator.