New Organosoluble and Optically Transparent Polyamides Containing Xanthene Units and Methyl Pendant Groups From 9,9-Bis[4-(4-carboxyphenoxy)-3-methylphenyl]xanthene

Abstract

A new aromatic dicarboxylic acid, 9,9-bis[4-(4-carboxyphenoxy)-3-methylphenyl]xanthene (BCAMPX) was prepared from the nucleophilic substitution reaction of 9,9-bis(4-hydroxy-3-methylphenyl)xanthene with p-fluorobenzonitrile, followed by alkaline hydrolysis. Then BCAMPX was polycondensated with various aromatic diamines to afford the polyamides with the number-average molecular weight in the range of 45,300–51,500 and the polydispersity index ranged from 1.67 to 1.85. These polyamides showed glass transition temperatures between 260–286°C and 10% weight loss temperatures ranging from 490 to 504°C and 480 to 490°C in nitrogen and air respectively, and char yields above 52% at 800°C in nitrogen. Nearly all polyamides were readily soluble polar aprotic solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide (DMAc), tetrahydrofuran and pyridine, and afforded transparent, strong and flexible films upon casting from DMAc solvent. All polyamides were amorphous and exhibited tensile strengths of 80–91 MPa, elongations at break of 9–13%, and initial moduli of 1.95–2.82 GPa, as well as low moisture absorption in the range of 2.65–3.65%, and high transparency with an ultraviolet–visible absorption cut-off wavelength in the 360–378 nm range.