Synthesis and Characterization of Some New Polyhydrazides by Direct Polycondensation in Ionic Liquid

Aseries of new polyhydrazides were obtained by direct polycondensation of 4,4 diphenyl sulphone dicarboxylic acid with dihydrazides in ionic liquids (ILs) as a new class of solvents which have interesting properties such as nonvolatility, high ionic concentration, good thermal stability and non-flammability. Direct polycondensation is successfully proceeded in ILs and triphenyl phosphite (condensing agent), without any additional components, such as LiCI and pyridine. Therefore IL can act as both solvent and catalyst. In this investigation high molecular weight polyhydrazides have been synthesized and their properties such as solubility, and thermal stability were studied. The resulting hydrazide containing polymers exhibited inherent viscosities in 0.26-0.73 dUg range. All polymers were soluble in polar solvents such as N-methyl pyrrolidone and dimethyl sulphoxide. The polyhydrazides had glass-transition temperatures (Tg) between 165-210°C. They could be thermally converted into the corresponding poly(1,3,4-oxadiazole)s approximately in the region of 210-330oC, as evidenced by the TGA thermograms.