Effect of Conformational Parameters on Thermal Properties of Some Poly(oxadiazole-naphthylimide)s

Two series of poly(oxadiazole-imide)s based on naphthalene-containinganhydrides and aromatic diamines having preformed oxadiazole rings have beensynthesized. One series contains four polymers: two of them are based onnaphthalene-1,4,5,8-tetracarboxylic dianhydride and the other two are based onbis(ketonaphthalic-anhydride). The other series contain four copolymers based onmixtures of these dianhydrides with hexafluoroisopropylidene-diphthalic anhydride.Most of these polymers are easily soluble in polar amidic solvents and even in lesspolar and convenient solvents, allowing them to be processed in thin films andcoatings. These polyimides and copolyimides show high thermal stability, with initialdecomposition temperature being above 430°C and glass transition temperature in therange of 190-318°C. Conformational rigidity parameters of these polymers have beencalculated by Monte Carlo method and discussed in relation with thermal properties.The values found experimentally for glass transition temperature correlate well withthose calculated by using the conformational rigidity parameters. The dependence ofglass transition temperature of these polymers on Kuhn segment can be described bylinear equations, with a very good factor of convergence.