THE SYNTHESIS AND CHARACTERIZATION OF POLYESTERS BASED ON 2,5-PYRIDINEDICARBOXYLIC ACID

A series of novel polyesters based on 2,5-pyridinedicarboxylic acid we re synthesized using the reaction of the caesium salt of the acid with a variety of dibromo compounds in N-methyl-2-pyrrolidone at 110-degre es-C. For the alpha, omega-dibromoalkane Br(CH2)mBr series, the effici ency of the polymerization increases as the chain length increases, th e highest weight-average molecular weight of M(w)BAR almost-equal-to 4 7 000 being obtained for the polymer with m = 10. All the polyesters w ere characterized by means of infrared and nuclear magnetic resonance spectroscopies, as well as elemental analysis. Solubility and thermal properties of these polyesters were determined and compared with their terephthalate analogues. The presence of the 2,5-pyridinediyl unit im proved the solubility behaviour and decreased the thermal stability. C ompared to the analogous terephthalates, the polymers showed slightly higher glass transition temperature and lower melting temperature valu es.