Supercritical carbon dioxide as an effective medium for poly(naphthoylenebenzimidazole)’s synthesis

Abstract A study of formation of poly(naphthoylenebenzimidazole)’s in supercritical CO 2 in the absence of any hazardous solvents was performed. Polycondensation reaction was performed in supercritical CO 2 at a temperature of 90 °C and a pressure of 15 MPa for 8 h in the presence of a catalyst – a mixture of benzoic acid and benzimidazole. A number of polymers were obtained and characterized by means of FTIR-spectroscopy, their amorphous structure was confirmed using X-ray diffraction. Decomposition temperatures of the synthesized polymers were revealed to be in the range of 450 °C–500 о C, the softening temperatures were in the range of 240 °C–365 о C. Depending on the polymer’s structure the dynamic light scattering method demonstrated either one- or bi-modal particle’s size distribution in N-methylpyrrolidone solutions. The investigation of optical properties of the polymers revealed yellow-orange light emission, which makes the synthesized polymers potential candidates for organic light-emitting devices.