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Salen Complexes as Fire Protective Agents for Thermoplastic Polyurethane: Deep Electron Paramagnetic Resonance Spectroscopy Investigation.
ACS Appl Mater Interfaces. 2018 Jul 25; 10(29):24860-24875.AA

Abstract

The contribution of copper complexes of salen-based Schiff bases N, N'-bis(salicylidene)ethylenediamine (C1), N, N'-bis(4-hydroxysalicylidene)ethylenediamine (C2), and N, N'-bis(5-hydroxysalicylidene)ethylenediamine (C3) to the flame retardancy of thermoplastic polyurethane (TPU) is investigated in the context of minimizing the inherent flammability of TPU. Thermal and fire properties of TPU are evaluated. It is observed that fire performances vary depending upon the substitution of the salen framework. Cone calorimetry [mass loss calorimetry (MLC)] results show that, in TPU at 10 wt % loading, C2 and C3 reduce the peak of heat release rate by 46 and 50%, respectively. At high temperature, these copper complexes undergo polycondensation leading to resorcinol-type resin in the condensed phase and thus acting as intumescence reinforcing agents. C3 in TPU is particularly interesting because it delays significantly the time to ignition (MLC experiment). In addition, pyrolysis combustion flow calorimetry shows reduction in the heat release rate curve, suggesting its involvement in gas-phase action. Structural changes of copper complexes and radical formation during thermal treatment as well as their influence on fire retardancy of TPU in the condensed phase are investigated by spectroscopic studies supported by microscopic and powder diffraction studies. Electron paramagnetic resonance (EPR) spectroscopy was fully used to follow the redox changes of Cu(II) ions as well as radical formation of copper complexes/TPU formulations in their degradation pathways. Pulsed EPR technique of hyperfine sublevel correlation spectroscopy reveals evolution of the local surrounding of copper and radicals with a strong contribution of nitrogen fragments in the degradation products. Further, the spin state of radicals was investigated by the two-dimensional technique of phase-inverted echo-amplitude detected nutation experiment. Two different radicals were detected, that is, one monocarbon radical and an oxygen biradical. Thus, the EPR study permits to deeply investigate the mode of action of copper salen complexes in TPU.

Authors+Show Affiliations

Univ. Lille, ENSCL, UMR 8207-UMET-Unité Matériaux et Transformations , F-59652 Villeneuve d'Ascq , France.Univ. Lille, ENSCL, UMR 8207-UMET-Unité Matériaux et Transformations , F-59652 Villeneuve d'Ascq , France.Univ. Lille, ENSCL, UMR 8207-UMET-Unité Matériaux et Transformations , F-59652 Villeneuve d'Ascq , France.Univ. Lille, CNRS, UMR 8516-LASIR-Laboratoire de Spectrochimie Infrarouge et Raman , F-59652 Villeneuve d'Ascq Cedex , France.Univ. Lille, CNRS, UMR 8516-LASIR-Laboratoire de Spectrochimie Infrarouge et Raman , F-59652 Villeneuve d'Ascq Cedex , France.Univ. Lille, CNRS, UMR 8516-LASIR-Laboratoire de Spectrochimie Infrarouge et Raman , F-59652 Villeneuve d'Ascq Cedex , France.Univ. Lille, ENSCL, UMR 8207-UMET-Unité Matériaux et Transformations , F-59652 Villeneuve d'Ascq , France.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

29957994

Citation

Naik, Anil D., et al. "Salen Complexes as Fire Protective Agents for Thermoplastic Polyurethane: Deep Electron Paramagnetic Resonance Spectroscopy Investigation." ACS Applied Materials & Interfaces, vol. 10, no. 29, 2018, pp. 24860-24875.
Naik AD, Bourbigot S, Bellayer S, et al. Salen Complexes as Fire Protective Agents for Thermoplastic Polyurethane: Deep Electron Paramagnetic Resonance Spectroscopy Investigation. ACS Appl Mater Interfaces. 2018;10(29):24860-24875.
Naik, A. D., Bourbigot, S., Bellayer, S., Touati, N., Ben Tayeb, K., Vezin, H., & Fontaine, G. (2018). Salen Complexes as Fire Protective Agents for Thermoplastic Polyurethane: Deep Electron Paramagnetic Resonance Spectroscopy Investigation. ACS Applied Materials & Interfaces, 10(29), 24860-24875. https://doi.org/10.1021/acsami.8b07323
Naik AD, et al. Salen Complexes as Fire Protective Agents for Thermoplastic Polyurethane: Deep Electron Paramagnetic Resonance Spectroscopy Investigation. ACS Appl Mater Interfaces. 2018 Jul 25;10(29):24860-24875. PubMed PMID: 29957994.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Salen Complexes as Fire Protective Agents for Thermoplastic Polyurethane: Deep Electron Paramagnetic Resonance Spectroscopy Investigation. AU - Naik,Anil D, AU - Bourbigot,Serge, AU - Bellayer,Séverine, AU - Touati,Nadia, AU - Ben Tayeb,Karima, AU - Vezin,Hervé, AU - Fontaine,Gaëlle, Y1 - 2018/07/16/ PY - 2018/6/30/pubmed PY - 2018/6/30/medline PY - 2018/6/30/entrez KW - EPR spectroscopy KW - Schiff bases KW - copper complex KW - flame retardancy KW - salen KW - thermoplastic polyurethane SP - 24860 EP - 24875 JF - ACS applied materials & interfaces JO - ACS Appl Mater Interfaces VL - 10 IS - 29 N2 - The contribution of copper complexes of salen-based Schiff bases N, N'-bis(salicylidene)ethylenediamine (C1), N, N'-bis(4-hydroxysalicylidene)ethylenediamine (C2), and N, N'-bis(5-hydroxysalicylidene)ethylenediamine (C3) to the flame retardancy of thermoplastic polyurethane (TPU) is investigated in the context of minimizing the inherent flammability of TPU. Thermal and fire properties of TPU are evaluated. It is observed that fire performances vary depending upon the substitution of the salen framework. Cone calorimetry [mass loss calorimetry (MLC)] results show that, in TPU at 10 wt % loading, C2 and C3 reduce the peak of heat release rate by 46 and 50%, respectively. At high temperature, these copper complexes undergo polycondensation leading to resorcinol-type resin in the condensed phase and thus acting as intumescence reinforcing agents. C3 in TPU is particularly interesting because it delays significantly the time to ignition (MLC experiment). In addition, pyrolysis combustion flow calorimetry shows reduction in the heat release rate curve, suggesting its involvement in gas-phase action. Structural changes of copper complexes and radical formation during thermal treatment as well as their influence on fire retardancy of TPU in the condensed phase are investigated by spectroscopic studies supported by microscopic and powder diffraction studies. Electron paramagnetic resonance (EPR) spectroscopy was fully used to follow the redox changes of Cu(II) ions as well as radical formation of copper complexes/TPU formulations in their degradation pathways. Pulsed EPR technique of hyperfine sublevel correlation spectroscopy reveals evolution of the local surrounding of copper and radicals with a strong contribution of nitrogen fragments in the degradation products. Further, the spin state of radicals was investigated by the two-dimensional technique of phase-inverted echo-amplitude detected nutation experiment. Two different radicals were detected, that is, one monocarbon radical and an oxygen biradical. Thus, the EPR study permits to deeply investigate the mode of action of copper salen complexes in TPU. SN - 1944-8252 UR - https://www.unboundmedicine.com/medline/citation/29957994/Salen_Complexes_as_Fire_Protective_Agents_for_Thermoplastic_Polyurethane:_Deep_Electron_Paramagnetic_Resonance_Spectroscopy_Investigation L2 - https://dx.doi.org/10.1021/acsami.8b07323 DB - PRIME DP - Unbound Medicine ER -
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