Syntheses and properties of aromatic polyamides and polyimides derived from 9,9‐bis[4‐(p‐aminophenoxy)phenyl]fluorene

Abstract 9,9‐Bis[4‐(p‐aminophenoxy)phenyl]fluorene (II) was used as a monomer with various aromatic dicarboxylic acids and tetracarboxylic dianhydrides to synthesize polyamides and polyimides, respectively. The diamineIIwas derived by a nucleophilic substitution of 9,9‐bis(4‐hydroxyphenyl)fluorene withp‐chloronitrobenzene in the presence of K2CO3and then hydro‐reduced. PolyamidesIVa‐ghaving inherent viscosities of 0.73–1.39 dL/g were prepared by the direct polycondensation of the diamineIIwith various aromatic diacids using triphenyl phosphite and pyridine as condensing agents. All the aromatic polyamides were amorphous and readily soluble in various polar solvents such asN,N‐dimethylacetamide,N,N‐dimethylformamide, dimethylsulfoxide, andN‐methyl‐2‐pyrrolidone. Transparent and flexible films of these polymers could be cast from the DMAc solutions. These aromatic polyamides had glass transition temperatures in the range of 283–309°C and 10% weight loss occurred up to 460°C. The polyimides were synthesized from diamineIIand various aromatic dianhydrides via the two‐stage procedure that included ring‐opening poly‐addition in DMAc to give poly(amic acid)s, followed by thermal or chemical conversion to polyimides. The poly(amic acid)s had inherent viscosities of 0.62–1.78 dL/g, depending on the dianhydrides. Most of the aromatic polyimides obtained by chemical cyclization were found to be soluble in NMP. These polyimides showed almost no weight loss up to 500°C in air or nitrogen atmosphere.