A facile approach towards large-scale synthesis of hierarchically nanoporous SnO₂@Fe₂O₃ 0D/1D hybrid and its effect on flammability, thermal stability and mechanical property of flexible poly(vinyl chloride)

Tin oxide (SnO₂) has versatile applications in a variety of areas. It also shows ability to improve the flame retardancy of flexible poly(vinyl chloride) (fPVC) composite and substitute the conventional toxic flame retardant-antimony trioxide (Sb₂O₃). However, low flame retardant efficiency and ruined thermal stability of the PVC composite in presence of SnO₂ remain to be the most prominent challenges. To address these issues, in this study, hematite (α-Fe₂O₃) zero-dimensional nanoparticles elaborately encapsulated SnO₂ one-dimensional nanorod assemblies and such nanocasting facilitated the formation of hierarchical porosity in favor of high specific surface area and pore volume. The hierarchically nanoporous hybrid was synthesized via a facile and fast bottom-up method in a large scale and all-sided characterization was conducted on the investigation of its structure and fPVC compositions. The extra benefits imparted by α-Fe₂O₃ in the hybrid improved the flame retardancy of fPVC composite strikingly with reduced amount of harmful HCl gas and suppressed smoke production, without deterioration of thermal stability and mechanical property, showing much better performance than those of Sb₂O₃-based fPVC composite. It indicated that this new eco-friendly nanohybrid had a great potential to totally replace antimonial additive. It is expected to pave the pathway about the construction of neoteric porous hybrid nanostructures and open a new avenue to develop high performance nanocomposites.