Thermally stable methyl-substituted poly(azomethine-ether)s bearing cardo cyclopentylidene moiety

A new diether-diamine monomer, 1,1-bis [4-(4-aminophenoxy)-3-methylphenyl]cyclopentane (BAMPC), containing a cardo cyclopentane unit and a pendant methyl substituent, was synthesized through a multistep procedure. The structure of the methyl-substituted diether-diamine monomer was confirmed using FT-IR, 1 H NMR, 13 C NMR, and mass spectrometry. Polycondensation of BAMPC with aromatic dialdehydes, including terephthalaldehyde and isophthalaldehyde, produced a series of co-poly (azomethine-ether)s incorporating cardo cyclopentane units in the polymer backbone. The influence of the cardo cyclopentane structure and pendant methyl group on the solubility and thermal stability of the resulting co-poly (azomethine-ether)s was examined. The polymers exhibited glass transition temperatures (Tg) in the range of 165-178°C and thermal degradation temperatures (T d ) between 456 and 486°C, indicating thermal stability. The polyazomethines were soluble in polar aprotic solvents such as DMF, NMP, DMAc, and DMSO at ambient temperature or upon heating. X-ray diffraction analysis indicated that SPAM-2, SPAM-3, SPAM-4, and SPAM-5 exhibited amorphous characteristics with a broad diffraction peak around 2θ ≈ 20°, whereas SPAM-1 showed semicrystalline behaviour. The inherent viscosities of the co-poly (azomethine-ether)s ranged from 0.20 to 0.39 dL g -1 .