New aromatic polyamides with 2,6-biphenylpyridyl moieties and 4-trifluoromethylphenyl pendent groups

Abstract

A new diamine, 4-(4-trifluoromethylphenyl)-2,6-bis(4-aminophenyl)pyridine, was synthesized and used in the preparation of the fluorinated polyamides with inherent viscosities of 0.67–0.96 dL g⁻¹ by direct polycondensation with aromatic dicarboxylic acids. The obtained polyamides have good solubility in many organic solvents such as N-methyl-2-pyrrolidinone, dimethylacetamide (DMAc), and tetrahydrofuran and exhibited glass transition temperatures between 275°C and 301°C, 10% weight loss temperatures (T _d10s) ranging from 502°C to 516°C, and char yields of 51–61% at 800°C under nitrogen atmosphere. Flexible and strong polymer films cast from DMAc solutions showed tensile strengths of 77.4–93.2 MPa, elongations at break of 9.2–14.3%, and initial moduli of 2.06–2.82 GPa. The polymer films also had good dielectric properties with dielectric constants of 3.22–3.50 (1 M Hz) and dissipation factors of 3.20–3.96 × 10⁻³, and acceptable electrical insulating properties, as well as low water uptake between 1.26% and 1.78%, and high transparency with an ultraviolet–visible absorption cutoff wavelength in the range of 330–371 nm. The remarkable combined features ensure these polymers to be ideal candidate materials for advanced microelectronic industry and other related applications.