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Living cationic ring‐opening polymerization of 3,4‐dihydro‐2H‐benzo[4,5]imidazo[2,1‐b]oxazine

The cationic ring-opening isomerization polymerization of 3,4-dihydro-2H-benzo[4,5]imidazo[2,1-b]oxazine (DBI) is reported for the first time. The polymerization of DBI with methyl trifluoromethanesulfonate proceeds smoothly at 35°C and gives poly(2,3-dihydro-lH-benzo[d]imidazol-2-one-1,3-diyltrimethylene) (polyDBI) in high yield. The narrow molecular weight distribution of the product as well as the results of postpolymerization revealed that the polymerization proceeds in a living fashion. PolyDBI is an amorphous white solid whose T g determined by DSC is 31 °C. TGA analysis showed that it is stable up to 475°C in nitrogen atmosphere.