Design Strategies Using Schiff Bases for Flame‐Retardant Epoxy Resins: A Review

ABSTRACT Epoxy resins are a widely used polymeric material for a wide range of applications. Nevertheless, the intrinsic flammable nature of epoxy resins limits their applications in extreme conditions. Chemists look for suitable flame‐retardants (FRs) to impart flame retardance to the epoxy resin. Adapting suitable organic synthetic approaches to synthesize FRs is always viable. Schiff base chemistry has emerged as a promising approach for developing FRs in epoxy resins, mainly due to its efficient char‐forming ability. The imine group (C N ) not only serves as a functional site for attaching FR agents like DOPO, but also contributes to flame retardance in the condensed phase by facilitating the formation of cross‐linked, nitrogen‐containing cyclic networks between Schiff base units. The present review provides an overview of possible approaches to make FRs for epoxy resins via Schiff base chemistries. The flame‐retardant mechanism of Schiff base‐containing epoxy thermosets is also proposed. Significant findings from multiple research groups, as well as major insights and viewpoints, are discussed.