SYNTHESIS AND CHARACTERIZATION OF 1,3,4-THIADIAZOLE-CONTAINING POLYETHERS FROM 2,5-BIS (4-FLUOROPHENYL)-L,3,4-THIADIAZOLE AND VARIOUS AROMATIC DIOLS

Seven 1,3,4-thiadiazole-containing polyethers with reduced viscosities of 0.27-1.44 dL/g were synthesized by the high-temperature solution p olycondensation of novel activated difluoride, 2,5-bis(4-fluorophenyl) -1,3,4-thiadiazole, with aromatic diols possessing a variety of ring s tructures. The expected chemical structures were confirmed by IR and H -1-NMR spectroscopy and elemental analysis. Of all the polymers, three polyethers were highly crystalline and soluble only in limited solven ts such as concentrated sulfuric acid. The other polyethers were amorp hous and dissolved easily in a variety of organic solvents including N -methyl-2-pyrrolidone (NMP), phenols, and chlorinated hydrocarbons. Co lorless to slightly yellow-colored, transparent, and tough films could be cast from the NMP solutions of the amorphous polyethers. The mecha nical properties of the films were excellent, and their tensile streng th, elongation at break, and tensile moduli were in the ranges of 48-7 2 MPa, 5-7%, and 1.3-1.9 GPa, respectively. The amorphous polyethers h ad high glass transition temperatures of 204-299 degrees C. All the po lyethers were highly thermally and thermooxidatively stable and exhibi ted no weight loss up to 400 degrees C, with 10% weight loss being rec orded at 464-513 degrees C in air. (C) 1994 John Wiley & Sons, Inc.