Syntheses and characterization of polycarbonates based on 1,1'-dihydroxyethyl-2,2'-biimidazole

Polycarbonates containing 2,2'-biimidazole were synthesized by the transesterification reaction of 1,1'-dihydroxyethyl-2,2'-biimidazole (HEB) and diphenyl carbonate (DPC). The experimental conditions for polymerization were also investigated in terms of the catalyst types, such as NaOMe and TiCl4. The maximum number average molecular weight (M-n = 24,800) of polymer was attained in case of equimolar ratio of HEB to DPC with 0.2% TICl4 as a catalyst and DMSO as solvent. When MaOMe was used as a catalyst. there was no significant difference in the molecular weight (13,000) compared with no catalyst case (10,900). FTIR and NMR spectral characterizations showed that the isolated poly mer exhibited a linear structure with regular incorporation of 2,2'-biimidazole units. The polymer decomposition was less than 9% at 200 degrees C in air.