Synthesis and characterization of coumarin-containing polyphosphazene

Novel coumarin-containing poly(organophosphazene) was prepared and its photodimerization characteristics were studied in this paper. Coumarin-containing polymer was synthesized by polymeric substitution reaction of highly reactive poly(dichlorophosphazene) with sodium salt of 7-(2-hydroxyethoxy)-4-methyl-coumarin. Chemical structure of polymer was characterized with FT-IR, NMR, GPC and elemental analysis. The number average molecular weight is 2.16 × 105 and the polydispersity index was 4.45 and Tg of 67.0 °C. The polymer was stable up to 280 °C. Under UV irradiation, the coumarin rings underwent [2 + 2] cycloadditional reaction to form insoluble curing film. The percentage gel content of irradiated polymer film was increased with increasing irradiation power and time. Upon irradiation with power of 97.2 mW/cm2, 96.7% gel content was reached in 30 mim.