A bis[pyrylium tetrafluoromethanesulfonate (triflate)], i.e. p-bis[4-(2,6-diphenylpyrylium)]benzene ditriflate) (3), has been prepared and polymerized with a series of aromatic diamines. The polymerizations, which were carried out in a dimethylsulfoxide (DMSO)/toluene mixture at 150 degrees C for 3-4 h, Even significantly faster than previous polymerizations of an analogous bis(pyrylium tetrafluoroborate). The poly(pyridinium triflate)s (5) obtained were soluble in polar aprotic solvents and had inherent viscosities that ranged from 8.3 to 18.7 dl/g (0.1 g/dl in DMSO at 30.0 +/- 0.1 degrees C). The rigid-rod polymers obtained from all-para-catenated diamines had viscosities comparable to those of other rigid-rod polyheterocyclics. All of the polymers could be solution cast into tough thin films that had moduli of 2.3-5.5 GPa. The poly(pyridinium triflate)s (5) were significantly more thermally and thermooxidatively stable than analogous poly(pyridinium tetrafluoroborate)s. The polymers underwent 5% weight losses near 451 degrees C in nitrogen and near 461 degrees C in air when subjected to thermal gravimetric analysis at a heating rate of 10 degrees C/min. The differences in the poly(pyridinium salt) stabilities were shown to be due to the differences in the stabilities of the counter ions. (C) 2000 Elsevier Science Ltd. All rights reserved.