Synthesis and characterization of new aromatic polyesters based on 8,16-methano-16H-dinaphtho[2,1-d:1′,2′-g][1,3]dioxocin-2,14-diol

Abstract

The bisphenol monomer containing dinaphthodioxocin group viz., 8,16-methano-16H-dinaphtho[2,1-d:1′,2′-g][1,3]dioxocin-2,14-diol (MDDD) was synthesized from commercially available 2,7-dihydroxynaphthalene and malonaldehydetetramethyl acetal and fully characterized by FT-IR, 1H, 13C NMR and mass spectroscopies. A series of new aromatic polyesters was synthesized by phase transfer-catalysed interfacial polycondensation or high temperature solution polymerization method. Optimal conditions for polyesterification were obtained via study of the model compounds. These polyesters were characterized by spectroscopic technique, viscosity measurement, solubility, thermal stability, DSC, and elemental analysis. Inherent viscosities and number average molecular weights (Mn) of polyesters were in the range 0.33–0.74 dl/g and 13,130–38,000 (Gel Permeation Chromatography, polystyrene standard). All of the new polymers show very good solubility in polar aprotic solvents and could be cast into transparent, flexible and apparently tough films. The glass transition temperature (Tg) of polyesters was in the range of 152–289 °C. Polyesters derived from MDDD and eight aromatic diacid chlorides did not show any weight loss below 330 °C and retained 23–43% weight at 600 °C. The temperature at 10% weight loss (T10), determined from thermogravimetric analysis of polyesters, was in the range 420–434 °C indicating their good thermal stability.