Synthesis and characterization of poly(dioxynaphthylene-1,4-dicarbonylnaphthylene)s with various isomeric naphthylene links

Summary

Six all-naphthylene polyesters were prepared by the condensation of 1,4-naphthalenedicarboxylic acid (NA) chloride with 1,4-, 1,5-, 1,6-, 2,3-, 2,6-, and 2,7-naphthalenediol (ND) isomers and effects of the isomerism of NDs on structure and properties of the polyesters were investigated.

The polymers-1,4,-1,5 and-2,6 with more or less linear ND link were insoluble and the others with bent ND link were soluble in the mixed solvent from phenol/p-chlorophenol/1,1,2,2-tetrachloroethane(TCE). The polymer-2,6 with the most linear ND link did not show a T_g and the highest decomposition initiation temperature(T_D) and T_g's and T_D's of the other polymers were only marginally dependent on their structures.

The polymer-2,3 is believed to have a macrocyclic structure consisting of four to six monomer units and the polymer-1,6 is amorphous in its stable chain conformation, while all the other polymers are semicrystalline. The polymers-1,4and-1,5 exhibited an irreversible crystal-to-crystal transition at 380 and 320°C, respectively, whereas the polymer-2,6 a reversible one at 240°C. The polymer-2,7 exhibited an irreversible crystal-to-amorphous transition at 360°C.