Graphene-containing flexible polyurethane porous composites with improved electromagnetic shielding and flame retardancy

Graphene/polyurethane (PU) porous composites combined the advantages of graphene and PU with high flexibility, electromagnetic shielding as well as fine flame retardant properties were prepared by a simple one-pot process. Graphene/PU composites with the density of 29.5 kg/m³ exhibited polygonal cell structure, which facilitated the multiple reflection attenuation of electromagnetic waves. The transmittance of the resulting composites to near infrared and mid-infrared bands was close to 0%, while the electromagnetic interference (EMI) shielding effectiveness (SE) reached 30 dB at low frequency band. The addition of flexible graphene sheets improved the flame retardancy and the flexibility of polyurethane. The peak heat release rate (PHRR) reduced from 518 to 395 kW/m², and the elongation at break reached 300%, which was recoverable. The introduction of graphene increased the thermal degradation temperature of PU and played a positive role in the thermal stability of graphene/PU composites. These ultra-light porous composites with high flexibility, EMI shielding and fine flame retardancy showed potential in the fields of flexible electronics and stealth materials.