Synthesis and characterization of novel benzhydrol-containing poly(amide-imide)s

International audienceA series of novel benzhydrol-containing poly(amide-imide)s (PAIs) have been prepared from a new diimide-dicarboxylic acid, N,N′-bis(4-hydroxycarbonyl)-benzhydrol-3,3′,4,4′-tetracarboxydiimide (BHTDA-DIA), with various diamines by direct polycondensation using triphenyl phosphite and pyridine as condensing agents. The polymers obtained had inherent viscosities of 0.35–0.96 dl g−1. All these PAIs, except polymer PAI-2, were soluble in N-methyl-2-pyrrolidinone and N,N-dimethylacetamide containing LiCl (1 wt%). Tough and flexible PAI films could be obtained by casting PAIs from their DMAc or NMP solutions, except for polymer PAI-2. The polymer films had a tensile strength of 93–111 MPa, an elongation at break range of 4–6%, and an initial modulus range of 2.7–3.8 GPa. The glass transition temperatures of most polymers were found to be above 255 °C. These polymers were fairly stable up to a temperature around or above 400 °C, and lost 10% weight in the range 426–507 °C in nitrogen and 423–515 °C in ai