Synthesis and characterization of novel nanostructured, organosoluble, thermally stable and wholly aromatic poly(amide-imide)s from a new diimide-diacid monomer by direct polycondensation

Abstract

In the present work, a new diimide-diacid monomer bearing pyridine rings was prepared. A series of novel nanostructured, organosoluble, thermally stable and wholly aromatic poly(amide-imide)s (PAIs) were synthesized from diimide-diacid, by direct polycondensation with various aromatic diamines in N-methyl-2-pyrrolidone using triphenyl phosphite and pyridine as a condensing agent. The nanostructured PAIs were achieved in good yields and possessed moderate inherent viscosities in the range of ηinh = 0.37–0.51 dL g−1. The synthesized polymers were characterized with FT-IR, 1H-NMR, UV–vis spectroscopy, elemental analysis, X-ray diffraction, field emission scanning electron microscopy (FE-SEM) and thermogravimetric analysis (TGA) techniques. All of the PAIs were amorphous in nature, were readily soluble in many organic solvents and could be solution cast into tough and flexible films. These polymers exhibited strong UV–vis absorption in the range of 294–311 nm in solution and in films. According to TGA data, these polymers exhibited initial decomposition temperature in the range of 396–433 °C, temperature of 10% weight loss from 446 to 537 °C, char yields more than 75% at 700 °C in nitrogen atmosphere and can be classified as self-extinguishing polymers. FE-SEM results show that, these nanostructured PAIs have spherical and cylindrical beads and the particle size is around 35–90 nm.