Molten salt ionic liquid-assisted synthesis of nano-structured poly(amide imide)s based on 4,4′-methylenebis(3-chloro-2,6-diethyl trimellit imidobenzene) via microwave process as an environmentally friendly methodology

Abstract

In this paper, for the first time, 4,4′-methylene-bis(3-chloro-2,6-diethyl trimellit imidobenzene) was prepared by the condensation reaction of 4,4′-methylene-bis(3-chloro-2,6-diethylaniline) and trimellitic anhydride. A series of novel poly(amide imide)s was prepared by the direct polycondensation of the synthesized diimide diacid and various commercial diamines using tetra-n-butylammonium bromide and triphenyl phosphite as a condensing agent under microwave irradiation. Tetra-n-butylammonium bromide acts both as a solvent and a catalyst to mediate clean polymerization reactions to yield the desired polymers. The obtained polymers were characterized with FTIR, ¹H NMR, X-ray diffraction, field emission scanning electron microscopy, elemental and thermogravimetric analysis. The poly(amide imide)s were generally soluble in polar organic solvents, such as N,N′-dimethyl acetamide, N,N′-dimethylformamide, N-methyl-2-pyrrolidone and sulfuric acid at room temperature, and are insoluble in methylene chloride, cyclohexane and water. Morphology probes showed these macromolecules were non-crystalline and nano-structured polymers. The effect of ultrasonic irradiation on the surface morphology of polymers was studied and the results demonstrated that the morphology of macromolecules after ultrasonication became more homogenous than it is before ultrasonic radiation. On the basis of thermogravimetric analysis data, such polymers are thermally stable and can be classified as self-extinguishing polymers.