Synthesis and characterization of new adamantane-based cardo polyamides

A novel series of cardo polyamides bearing the 2,2-adamantylidene unit were directly prepared from a new adamantane-based dietheramine, 2,2-bis[4-(4-aminophenoxy)phenyl]adamantane, with various aromatic dicarboxylic acids using triphenyl phosphite (TPP) and pyridine as condensing agents. These polyamides had inherent viscosities ranging from 0.44 to 0.89 dL/g. All the polymers showed an amorphous nature by X-ray diffraction measurements, and most of them were easily soluble in polar aprotic solvents such as NMP and DMAc. The flexible and tough films cast from the polymer solutions possessed a tensile strength of 91–101 MPa and an elongation-at-break of 5–13%. The polyamides were thermally stable up to 450°C in air or in nitrogen. Most of them revealed distinct glass transition on the differential scanning calorimetry (DSC) traces, and their Tgs were recorded in the range of 230–269°C . Softening temperatures (Ts) of these polyamides were in the range of 272–308°C by thermomechanical analysis (TMA).