Synthesis of aromatic, soluble, and thermally stable polyamides derived from new diamine containing unsymmetrical phenolphthalein and imidazole pendent group

Abstract

A novel diamine monomer containing unsymmetrical phenolphthalein and triaryl imidazole pendant group, 3,3-bis(4-(4-amino-2-(4,5-diphenyl-1H-imidazol-2-yl)phenoxy)phenyl)isobenzofuran-1(3H)-one (BADPPI), was successfully prepared in three steps. The novel diamine monomer BADPPI was directly polymerized with commercially available diacids, such as terephthalic acid, isophthalic acid, pyridine-2,6-dicarboxylic acid, and adipic acid, to obtain corresponding polyamides (PAs). The resulting novel aromatic PAs were obtained in high yields and moderate inherent viscosities in the range of 0.52–0.57 dL g−1 and exhibited excellent solubility in aprotic polar solvents, such as N,N-dimethylacetamide , N-methyl-2-pyrrolidone, N,N-dimethylformamide, dimethyl sulfoxide, tetrahydrofuran, meta cresol, and pyridine. PAs showed high glass-transition temperatures between 191°C and 277°C. Thermogravimetric analysis of the PAs indicated a 10% weight loss ( T10%) in the temperature range of 382–473°C and char yields at 600°C under nitrogen atmosphere in the range of 56–70% depending on the diacids monomer used for the PAs preparation.