Synthesis and characterization of polyazodiphenylene phenylphosphonates

A new polyazophosphonate, polyazodiphenylene phenylphosphonate (PAPPP) was obtained by the interfacial polycondensation of phenylphosphonic dichloride with 4,4-dihydroxyazobentene, The structure of the polymer was confirmed b y FTIR, H-1 NMR, P-31 NMR and elemental analysis, The thermal behavior was evaluated by DSC and TG, the high residue of PAPPP is due to the presence o f nitrogen and phosphorus in the same mainchain, Nitrogen appears to have a somewhat synergistic flame retardant effect with phosphorus, PET samples c ontaining 5% and 10% (mass ratio) PAPPP have limiting oxygen index values o f 28.2 and 33.4. It may be concluded that nitrogen-containing polyphosphona te possesses superior flame retardancy.