Synthesis and properties of noncoplanar rigid-rod aromatic polyamides containing phenyl or naphthyl substituents

A series of novel aromatic polyamides having noncoplanar biphenylene units in the main chain and bulky naphthyl or phenyl pendant group at 2,2'-disubstituted position were prepared from the two rigid-rod aromatic dicarboxylic acid monomers, 2,2'-diphenylbiphenyl-4,4'-dicarboxylic acid (1) and 2,2'-dinaphthylbiphenyl-4,4'-dicarboxylic acid (2), and various aromatic diamines. These polyamides were readily soluble in many organic solvents and showed excellent thermal stability associated with high glass-transition temperatures in the range of 229-292 degrees C. These polymers also exhibited strong UV-Vis absorption bands at 262-353 nm in NMP solution, and their photoluminescence spectra showed maximum bands at 440-462 nm in the purple to blue region. The poly(amine-amide) IId derived from the diamine with triphenylamine moieties revealed excellent electrochromic contrast and coloration efficiency, changing color from the pale yellowish neutral form to green then to the blue oxidized forms when scanning potentials positively from 0.00 to 1.30 V.