Crossing the Traditional Boundaries: Salen-Based Schiff Bases for Thermal Protective Applications.
A broad spectrum of applications of "Salen"-based Schiff bases tagged them as versatile multifunctional materials. However, their applicability is often bounded by a temperature threshold and, thus, they have rarely been used for high temperature applications. Our investigation of a classical Schiff base, N,N'-bis(4-hydroxysalicylidene)ethylenediamine (L2), reveals that it displays an intriguingly combative response to an elevated temperature/fire scenario. L2 resists and regulates thermal degradation by forming an ablative surface, and acts as a thermal shield. A polycondensation via covalent cross-linking, which forms a hyperbranched cross-linked resin is found to constitute the origin of the ablative surface. This is a unique example of a resin formation produced with a Schiff base, that mimicks the operational strategy of a high-heat resistant phenolic resin. Further applicability of L2, as a flame retardant, was tested in an engineering polymer, polyamide-6. It was found that it reinforces the polymer against fire risks by the formation of an intumescent coating. This paves the way for a new strategic avenue in safeguarding polymeric materials toward fire risks. Further, this material represents a promising start for thermal protective applications.
ISP/UMET-UMR/CNRS 8207, Ecole Nationale Supérieure de Chimie de Lille (ENSCL) , Avenue Dimitri Mendeleïev-Bât. C7a, BP 90108, 59652, Villeneuve d'Ascq Cedex, France.
Anil D
AD
Naik
ISP/UMET-UMR/CNRS 8207, Ecole Nationale Supérieure de Chimie de Lille (ENSCL) , Avenue Dimitri Mendeleïev-Bât. C7a, BP 90108, 59652, Villeneuve d'Ascq Cedex, France.
Gaëlle
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Fontaine
ISP/UMET-UMR/CNRS 8207, Ecole Nationale Supérieure de Chimie de Lille (ENSCL) , Avenue Dimitri Mendeleïev-Bât. C7a, BP 90108, 59652, Villeneuve d'Ascq Cedex, France.
Séverine
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Bellayer
ISP/UMET-UMR/CNRS 8207, Ecole Nationale Supérieure de Chimie de Lille (ENSCL) , Avenue Dimitri Mendeleïev-Bât. C7a, BP 90108, 59652, Villeneuve d'Ascq Cedex, France.
Serge
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Bourbigot
Flame retardancy; Phenolic resin; Polymers; Resorcinol; Salen; Schiff base