Synthesis and characterization of polyiminobenzothiazoles

A series of polyiminobenzothiazoles was synthesized by the polymerization of either 2,6-dichloro- or 2,6-diphenoxybenzobisthiazole with a number of aromatic diamines. A polymer was also obtained from the self-condensation of either 2-chloro- or 2-phenoxy-6-aminobenzothiazole. The polymers were characterized by their elemental analysis and infrared spectra. Thermogravimetric analysis, differential thermal analysis, and softening under load were used to evaluate their thermal properties. The polymers were found to be light tan to brown powders which showed only slight softening below their decomposition temperatures. Onset of breakdown under thermogravimetric analysis in a nitrogen atmosphere generally occurred at 375–400°C. The polymers were sparingly soluble in organic solvents and had inherent viscosities in the range of 0.11–0.55.