Studies on the synthesis and properties of soluble homo‐ and copolyester–imide derived from imide–diacid

A series of polyester–imides was prepared from diacid (imid–diacid [M1–M4] or a mixture of imide–diacid and terephthalic acid [TPA]) and bisphenol A in the presence of diphenyl chlorophosphate (DPCP) and pyridine as a direct condensation agent. The inherent viscosites of homo‐ and copolyester–imides were in the range of 0.39–0.58 dL/g. Almost all these homo‐ and copolyester–imides were completely soluble in N‐methyl‐2‐pyrrolidone (NMP), N,N‐dimethylacetamide (DMAC), dimethylformamide (DMF), and m‐cresol. The thermal properties of homo‐ and copolyester–imides were examined by DSC and TGA. These copolyester–imides had glass transition temperatures in the range of 95–240°C and a 5% weight loss was observed in the range of 354–465°C.