Synthesis and properties of a novel polyarylate with 9,10-dihydrophenanthrene-2,7-dicarbonylate moiety

A novel wholly aromatic polyester poly[oxy-1,4-phenylene(1-methylethylidene)-1,4-phenyleneoxycarbonyl(9,10- dihydr o-2,7-phenanthrenediyl)-carbonyl] (I) was synthesized by palladium catalyzed carbonylation-polycondensation with 2,7-dibromo-9,10-dihydrophenanthrene and bisphenol-A. Polyarylate (I) obtained in 95% yield with high molecular weight (polystyrene equivalent M_w=102,600) under optimum conditions, and was highly heat-resistant and soluble in organic solvent such as chlorobenzene, dichloromethane, and chloroform. The initial thermal degradation temperatures of poly arylate (I) are 332-420°C in the air atmosphere and 420-483°C under a nitrogen stream. Activation energy of oxidizing degradation reaction in the air atmosphere was 89 KJ/mol. The intrinsic viscosity of polyarylate (I) was 0.46, and their viscosities under the steady shear flow were 22, 250 and 7200 mPa.s at the concentration of 5, 10 and 20 g/dl, respectively. The tensile strength at break and tensile modulus were 44.5 MPa and 1.23 GPa, respectively: these properties are roughly in the same level as those of conventional unsaturated polyester resin. Polyarylate (I) exhibits the dynamic viscoelastic behavior for like typical amorphous polymer. Dynamic viscoelastic curve showed that the glass transition temperature was about 270°C