Fluorinated polyamides and poly(amide imide)s based on 1,4‐bis(4‐amino‐2‐trifluromethylphenoxy)benzene, aromatic dicarboxylic acids, and various monotrimellitimides and bistrimellitimides: Syntheses and properties

A CF 3 ‐containing diamine, 1,4‐bis(4‐amino‐2‐trifluromethylphenoxy) benzene ( I ), was prepared from hydroquinone and 2‐chloro‐5‐nitrobenzotrifluoride. Imide‐containing diacids ( V a–h and VI a,b ) were prepared through the condensation reaction of amino acids, aromatic diamines, and trimellitic anhydride. Then, a series of soluble fluorinated polyamides ( VII a–h ) and poly(amide imide)s ( VIII a–h and X a,b ) were synthesized from I with various aromatic diacids ( II a–h ) and imide‐containing diacids ( V a–h and VI a,b ) via direct polycondensation with triphenyl phosphate and pyridine. The polyamides and poly(amide imide)s had inherent viscosities of 1.00–1.70 and 0.79–1.34 dL/g, respectively. All the synthesized polymers showed excellent solubility in amide‐type solvents such as N ‐methyl‐2‐pyrrolidinone, N,N ‐dimethylacetamide, and N ‐dimethylformamide and afforded transparent and tough films via solvent casting. Polymer films of VII a–h , VIII a–h , and X a,b had tensile strengths of 91–113 MPa, elongations to break of 8–40%, and initial moduli of 2.1–2.8 GPa. The glass‐transition temperatures of the polyamides and poly(amide imide)s were 254–276 and 255–292 °C, respectively, and the imide‐containing poly(amide imide)s had better thermal stability than the polyamides. The polyamides showed higher transparency and were much lighter in color than the poly(amide imide)s, and their cutoff wave numbers were below 400 nm. In comparison with isomeric IX c – h , poly(amide imide)s VIII c–h exhibited less coloring and showed lower yellowness indices.