Synthesis and characterization of poly(pentabromostyrene) micrometer-sized particles of narrow size distribution for flame-retardant applications

Flame-retardant microspheres are important due to their ability to increase the thermal stability of host materials. Bromine-containing compounds have been used for centuries due to their flame-retardant properties. A problem with many currently used fire retardants is their escape from their host material, decreasing their effectiveness as well as polluting the environment. In this work, a pentabromostyrene (PBS) monomer was synthesized and polymerized by dispersion polymerization for preparation of flame-retardant microspheres. The effect of various polymerization parameters on their size and size distribution was also elucidated. In order to demonstrate the potential of poly(PBS) microspheres as flame retardants, poly(PBS)/polystyrene (poly(PBS)/PS) blends were prepared, and it was shown that the higher the percentage of poly(PBS) in the blend, the higher the combustion temperature. An additional test for the performance of the poly(PBS) microparticles as flame-retardant additives was performed by coating polyethylene terephthalate (PET) films with the poly(PBS) microspheres, decreasing their flammability, as was illustrated by a vertical burn test. The high thermal stability and low flammability of both the poly(PBS) particles and the poly(PBS)/polymer blends indicate the potential of these microspheres as flame-retardant additives.