Synthesis and properties of polyamides derived from 4,6-bis(4-chloroformylphenylthio)pyrimidine and 3,6-bis(4-chloroformylphenylthio)pyridazine

Two kinds of monomers containing thioether units 4,6-bis(4-chloroformylphenylthio)pyrimidine (BPPM-DC) and 3,6-bis(4-chloroformylphenylthio)pyridazine (BPPD-DC) were synthesized by two steps and were reacted with diamine-containing thioether (−S–) and sulfone units to prepare a kind of polyamide containing heterocycles and high contents of thioether groups. These polyamides had good optical properties, including an optical transmittance of the aromatic polyamide film at 450 nm that was higher than 87%. Additionally, the pyridazine, pyrimidine and the large quantity of thioether units provided the polymers with high refractive indices of 1.722–1.732 and low birefringences of 0.004–0.006. These polyamides were also found to have good thermal properties. They showed improved solubility in polar aprotic solvents and could form tough films with a tensile strength of 79.2–112.3 MPa and a storage modulus of 1.4–2.4 GPa (at 200 °C).© 2013 Society of Chemical Industry