Graphene-based flame-retardant polyurethane: a critical review

Polyurethane foams (PUFs) are widely used in several applications including fire-alarm sensors, electromagnetic interference shielding, insulation material, and anti-corrosion coating. On the other hand, PUFs are highly flammable and their further development is dependent on their fire retardancy property. Therefore, development of PUFs with fire-retardant properties has been at the core of attention in recent years. Graphene-based nanomaterials (GNs) such as graphene and graphene oxide improve the thermal stability of PUFs and delay their ignition. In addition, GNS can suppress fire from spreading during PUFs burning. Despite the outstanding properties of GNs, their sheets may stack, shrink, and lose their large surface area. This directly affects their dispersion and compatibility with the parent polymer. To address these challenges, GNs can be modified with namely intumescent including an acid source, a gas source, and a carbon source and non-intumescent with zero, one, and 2D assembly materials. Incorporating modified GNs FRs into PUFs is performed using both surface coating, reactive, or additive methods. In the present review, the state-of-the-art reports on the use of modified GNs into PUFs have been highlighted. Moreover, the challenges of GNs flame-retardant PUFs as well as various strategies to tackle these challenges and improve the flame retardancy of PUFs are stated.

Automated summary

Polyurethane foams (PUFs) are widely used but highly flammable, and the development of PUFs with fire-retardant properties is crucial. Graphene-based nanomaterials (GNs) improve the thermal stability of PUFs and delay ignition. However, the sheet structure of GNs affects their dispersion and compatibility, which can be addressed through modification.