Thermal behaviour and molecular modelling of some aromatic polyethers containing a hexamethylenic spacer

We report a study of the thermal stability of some aromatic copolyethers containing a hexamethylenic spacer. The polymers were synthesized by phase transfer catalysis (in a liquid/liquid system) starting from 1,6-dichlorohexane and different bisphenols: 4,4′-dihydroxyazobenzene, 4,4′-dihydroxydiphenyl, bisphenol A and 2,7-dihydroxynaphthalene. Thermal stability was investigated by thermogravimetric analysis, in a static air atmosphere the heating rate being 10°C/min. Molecular modeling was used as a complementary analysis method for the best understanding of the relationship between the chain conformation and polarity and the thermal behavior. CERIUS2 and HYPERCHEM programs were used to perform the molecular modelling. All the synthesized polymers present similar values of the starting point of the weight loss. This behavior can be explained by supra-molecular ordering, which is probably more important than the chemical structure. The presence of the hexamethylenic spacer leads to a micro-phase separation, with a favourable influence on the ordering in the solid state. All polymers showed low values of the polar surface, with interchain interactions playing a secondary role in the thermal stability