First phosphorus AB₂ monomer for flame-retardant hyperbranched polyphosphoesters: AB₂ Vs. A₂ + B₃

Branched polymers are an important class of polymers with a high number of terminal groups, lower viscosity compared to their linear analogs and higher miscibility, which makes them especially interesting for flame retardant applications, where the flame retardants (FR) are blended with another polymer matrix. Hyperbranched polyphosphoesters (hbPPEs) are gaining more and more interest in the field of flame retardancy, as low molar mass FRs often have the disadvantage of blooming out or leaching, which is not desired in consumer products. Here, we present the first phosphorus-based AB2 monomer for the synthesis of hbPPEs and assess its flame-retardant performance in an epoxy resin compared to a hbPPE synthesized by an A₂ + B₃ approach. The hbPPE synthesized from an AB2 monomer exhibited a slightly higher performance compared to a similar hbPPE, which was prepared by A₂ + B₃ polyaddition, probably due to its higher phosphorus content.