Synthesis and properties of new highly soluble poly(amide-ester-imide)s containing poly(ethylene glycol) as a soft segment

In this study, a new class of highly soluble poly(amide-ester-imide)s (PAEI)s contains poly(ethyleneglycol) (PEG) as hydrophilic and soft segment were prepared. Poly(ethylene glycol)-bis-(N-trimellitylimido-4-phenyl carboxylic acid) (3) as a novel diacid monomer was synthesized via two step. The reaction of poly(ethylene glycol) (PEG 6000) with trimellitic anhydride chloride yield poly(ethylene glycol)-bis-trimellitic anhydride (1). The reaction of dianhydride 1 with p-aminobenzoic acid (2) produces novel diacid monomer 3. The direct polycondensation technique of the diacid 1 with several aromatic diamines was carried out in pyridine/N-methyl-2-pyrrolidone/triphenylphosphite/CaCl₂ as condensing agent. The resulting novel PAEIs with inherent viscosities ranging between 0.21 and 0.42 dl g⁻¹, were obtained in good yield. This group of polymers exhibit excellent solubility in a variety of organic solvents and water. All of these polymers were characterized with FT-IR spectroscopy. Thermal properties, ¹H-NMR and XRD study of these PAEIs were also reported. The results demonstrate that this polymers show crystalline structure as well as high thermal stability. In addition the effect of PEG length on solubility and thermal properties of the polymers were also studied.