Regulating High-Temperature Reversible Thermochromism in Structurally Symmetric Polydiacetylene Derivatives via...

Thermal monitoring constitutes an essential safeguard against potential hazards arising from thermal runaway events. To address diverse application requirements, various thermal indicators have been progressively developed. In this study, three symmetrically structured amide-functionalized polydiacetylenes (poly(DCDA-1), poly(DCDA-2) and poly(DCDA-3)) are synthesized for the first time through topochemical polymerization using cost-effective 10-undecynoic acid as the precursor. That dynamic structural modifications of functional groups and conjugated backbones under thermal stimuli are unveiled by in situ FTIR spectroscopy. Complementary in situ XRD analyses quantify temperature-dependent interlayer spacing variations, demonstrating progressive expansion upon heating that correlated with chromatic shifts. The structural integrity of unsaturated moieties during thermal cycling is confirmed by Raman spectra. The differences in room-temperature color and UV-vis absorption spectra among the three PDAs are confirmed through theoretical calculations. The combination of superior reversible thermochromic characteristics and pronounced chromatic contrast positions poly(DCDA-3) as a promising candidate for efficient and reusable thermal sensing applications.