Synthesis and properties of poly(dioxynaphthyleneisophthaloyl)s with various isomeric naphthylene links

Summary

By condensation of 1,4-, 1,5-, 1,6-, 2,3-, 2,6-, and 2,7-naphthalenediol (ND) isomers with a isophthaloyl chloride six aromatic polyesters were prepared, and after removal of low molecular weight materials by extraction with acetone their properties were investigated. Effects of the isomerism of the naphthylene units on the properties of the polyesters were discussed. All the polyesters except one derived from 2,7-ND were soluble in a mixed solvent of phenol/p-chlorophenol/1,1,2,2-tetrachloroethane (TCE). Weight-average molecular weight of the polymer derived from 2,3-ND having the lowest inherent viscosity of 0.10 dL/g was measured to be 12,200 g/mol in TCE by means of a laser light scattering spectrometer. Polydispersity of this sample was determined to be 1.59 by a gel permeation chromatography with o-chlorophenol at 100°C. Glass transition temperatures of the polymers ranged from 144 to 195°C, depending on their molecular weight and chain structure. The polyesters derived from 1,6- and 2,3-NDs were amorphous and all the others were crystalline. Melting temperatures (T_m) of the polymers range from 341°C to 417°C and the polymer derived from 2,6-ND showed the highest T_m. All the polymers had initial decomposition temperature higher than 400°C and showed residue more than 50 wt% at 600°C.