Novel heat resistant nanostructure poly (amide–imide) s containing new TMA-based diacid via conventional polycondensation reaction in an ionic green medium: synthesis, morphology, and thermal properties

The 4,4′-Methylenebis(3-chloro-2,6-diethylaniline) has been reacted with two moles of trimellitic anhydride in refluxing N,N′-dimethylformamide to obtain 4,4′-Methylenebis(3-chloro-2,6-diethyl trimellitimidobenzene) for the first time. A series of novel poly(amide–imide)s (PAIs) was synthesized by the direct polycondensation of the synthesized diimide–diacid with various commercial diamines. The direct polyamidation was performed under conventional heating reaction using tetra-n-butylammonium bromide and triphenyl phosphite as a condensing agent. The PAIs were obtained in good yields and moderate inherent viscosity up to 0.48 dL/g. Although the polymers were not soluble in low polar solvents tested, they were thoroughly dissolved in high polar solvents and even in a moderate polar solvent such as pyridine. The crystallinity of the prepared PAIs was measured by XRD scans. No remarkable crystal diffraction was detected for the polymers obtained, and they showed almost an amorphous diffraction patterns. The thermal behavior of the polymers was evaluated by thermogravimetric analysis (TGA) technique. This study showed obviously one-stage decomposition at elevated temperatures. On the basis of TGA data, such polymers are thermally stable and can be classified as self-extinguishing polymers. The structural features of these polymers were verified by elemental analysis, fourier transform infrared spectroscopy, and ¹H-NMR spectroscopies. The field emission scanning electron microscopy (FE-SEM) micrographs showed the obtained PAIs have nanostructure morphology. The effect of ultrasonic irradiation on the polymer morphology was studied. The FE-SEM micrographs illustrated that the morphology of macromolecules after ultrasonication became more homogenous than it is before ultrasonic radiation.