Flame retardancy and smoke suppression of multi-metal doped mesoporous bio-glass based hybrid microsphere on epoxy resin

Bioactive glass (BG) has been a focus of research for biomedical applications due to its unique biological properties. Owning to its special composition (SiO 2 –CaO–P 2 O 5 ) and structure, BG becomes a potential flame retardant. In this paper, a novel type of BGs was synthesized and employed as a flame retardant for epoxy resin (EP). To further improve its flame retardancy properties, firstly, the chemical compositions of BGs were modified by doping Cu, Zn, Sr ions into the SiO 2 network by a sol-gel method combined with a template method and hydrothermal method; secondly, the microstructure of BGs was designed as a microsphere with a hollow mesoporous structure. Moreover, the obtained BGs were further functionalized with a polyphosphazene derivative (PZS) to integrate the excellent flame retardancy and mechanical properties. The results showed that Cu/Zn/Sr ions entered the SiO 2 network, while PZS was successfully deposited on the surface of mesoporous BGs. An improved comprehensive performance including flame retardancy, smoke suppression and mechanical strength enhancement was achieved by the presence of multiple flame-retardant atoms (Cu, Zn, Sr, Si, P, S, N, Cl) in the mesoporous BG microspheres. This study successfully applied BGs with high biocompatibility as flame retardant, broadening the types and categories of flame retardants.