Abstract :
[en] This work presents non‐isocyanate polyurethane (NIPU) films of the polyhydroxyurethane (PHU)‐type, characterized by pendent vicinal diol groups, as highly effective materials for humidity sensing and monitoring of matrix hydroplasticization. These films eliminate the need for fluorophores, as they exhibit inherent, unconventional fluorescence based on clusteroluminescence. This fluorescence originates from extensive hydrogen bonding and electron‐rich heteroatomic sub‐luminophores. The fluorescence properties of these films are highly sensitive to environmental humidity. As relative humidity increases, both fluorescence intensity and lifetime decrease linearly. This phenomenon is attributed to the disruption of hydrogen bonding by absorbed water molecules, which alters the clusteroluminescence mechanism. Furthermore, the fluorescence response also reflects the hydroplasticization of the NIPU matrix. A linear correlation is observed between relative fluorescence intensity and the glass transition temperature (Tg), enabling the first‐ever use of nonconventional fluorescence to monitor Tg variations as a function of humidity. These findings demonstrate the dual functionality of non‐isocyanate PHU‐type films as accessible, fluorophore‐free materials for real‐time humidity sensing and monitoring of softening behavior in these NIPU matrices.
Funding text :
M.M. is grateful to the Sector Council for Research and Valorisation in Science and Techniques of University of Liege (ULiège) for fund- ing. This research was supported by the ULiège under Special Funds for Research, IPD-STEMA Programme, and the Region Wallonne in the frame of the WEL-T-CR-2023 project Chemistry (convention WEL-T-CR- 2023 A). Computational resources have been provided by the Consortium des Équipements de Calcul Intensif (CÉCI), funded by the Fonds de la Recherche Scientifique de Belgique (F.R.S.-FNRS) under Grant No. 2.5020.11 and by the Walloon Region. The authors acknowledge the Robotein platform ofthe BE Instruct-ERIC Center for providing access to the Fluorescence microplate reader. The authors thank Gaëtan Lefevre from the GIGA Cell Imaging Platform (University of Liège, Belgium) for his expertise, help, and advice. CD is FNRS Research Director and thanks the Fonds de la Recherche Scientifique (F.R.S.-FNRS) for funding. CD, BG, andMB thank the RegionWallonne for funding the Win2Wal project “ECO- FOAM” (convention 2010130). The results presented were made possible thanks to infrastructure acquired under Measure BE-C[C72]-I[I-711], Re- search Platform for Energy Transition of the French Community, funded through the REPowerEU chapter ofthe NextGenerationEU plan.
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