Controlled release of phosphorus-containing free radical from the porous channels of metal–organic frame to reduce the combustion heat and smoke releases of polystyrene

The combustion of polystyrene (PS) releases enormous amounts of smoke and heat, which seriously affects individuals and property safety. This research employed a porous metal–organic framework (P-Fe-MOF) with excellent adsorption properties to fix 1,1'-bis(diphenylphosphino)ferrocene (BDF) into its porous channels to form a novel flame-retardant system. The peak heat release rate (PHRR) of the neat PS is reduced by 49.3% (from 1128 to 572 kW m⁻²) with the addition of 3 mass% of D-Fe-MOF, while the time to reach the peak is delayed form 170 to 250 s. Additionally, there is an obvious enhancement in thermal stability. The temperature at initial mass losses is significantly delayed from 331 °C for bulk PS to 379 °C for PS/D-Fe-3.0. And the char residue at 700 ℃ is increased from 1.27 to 3.24 mass%. Compared with pure PS, the char residue of PS/D-Fe-MOF is continuous and dense due to the excellent catalytic performance of D-Fe-MOF in the combustion of composites. This research presents a new flame-retardant design strategy and reduces the fire risk of PS, which provides valuable enlightenment for broadening the application field of MOF and improving the comprehensive properties of polymers.