Nano-architectured mesoporous silica decorated with ultrafine Co3O4 toward an efficient way to delaying ignition and improving fire retardancy of polystyrene

Aiming to impart polystyrene (PS) with delayed ignition and improved fire retardancy, mesoporous silica SBA-15 decorated with Co3O4 ultrafine nanoparticles (SBA-15@Co3O4) was nano-architectured successfully via multi-step microwave radiation approach. The design principles included: 1) SBA-15 offered the absorbing and labyrinth effect of volatiles 2) the homogeneous and ultrafine dispersion of Co3O4 on SBA-15 interior walls endowed more interacting sites to volatiles. In detail, the obtained SBA-15@Co3O4 was firstly verified using FTIR, Raman, XRD, SEM, TEM and N-2 sorption measurement. Compared with neat PS and PS/SBA-15 composites, PS composites with SBA-15@Co3O4 demonstrated significantly enhanced thermal and thermo-oxidation stability. Meanwhile, PS composite with 2 wt% SBA-15@Co3O4 (PS/2SBA-15@Co3O4) had a notably better fire retardancy with time to ignition (TTI) value of 116 +/- 2 s, which was obviously higher than those of PS (98 +/- 1 s) and PS/2SBA-15 (106 +/- 1 s). Thermogravimetric analysis coupled with FTIR (TG-FTIR) and mass spectrometry (TG-MS) measurement revealed the probable mechanism of reduced heat release and delayed TTI, which was involved in the adsorption-desorption-combustion mode. Moreover, tensile test illustrated that SBA-15@Co3O4 notably improved the mechanical property of PS. Through this study, nano-architecture of functionalized hybrid offered a novel idea to delay ignition, decrease flammability while improve the mechanical properties for polymeric materials.