Synthesis and properties of polyamides based on a spirobichroman bis(ether‐carboxylic acid)

High molar‐mass aromatic polyamides were obtained from 7,7'‐bis(4‐carboxyphenoxy)‐4,4,4′,4′‐tetramethyl‐2,2′‐spirobichroman, a novel dicarboxylic acid monomer, by direct polycondensation reaction in N ‐methyl‐2‐pyrrolidone (NMP) with various aromatic diamines, using triphenyl phosphite and pyridine as condensing agents. Polyamides having inherent viscosities of 0,73–1,08 dL/g were obtained in quantitative yield. All the polyamides, even that derived from benzidine, are completely amorphous and readily soluble in a variety of organic solvents such as NMP, N , N ‐dimethylacetamide (DMAc), N , N ‐dimethylformamide (DMF), and m ‐cresol. Their solutions can be cast into transparent, flexible and tough films. All the polyamides show distinct glass transitions in the range of 182–235°C on their differential scanning calorimetry (DSC) traces. The 10% weight loss temperatures in nitrogen and air are above 416 and 422°C, respectively.