Thermally stable polymers from 1,4,5,8‐naphthalenetetracarboxylic acid and aromatic tetraamines

Abstract

Abstract Polycondensations of 1,4,5,8‐naphthalenetetracarboxylic acid (NTCA) with both 3,3′‐diaminobenzidine (DAB) and 1,2,4,5‐tetraaminobenzene tetrahydrochloride (TAB) in polyphosphoric acid (PPA) were found to produce soluble polymers which exhibit excellent thermal stabilities. Polymer structures were deduced from infrared, thermal, and elemental analyses of model compounds and polymers. Polymer derived from TAB had a ladder‐type structure. Polymers with solution viscosities near 1 or above (determined in H 2 SO 4 ) were obtained from polymerizations near 200°C., and analysis showed these to possess a very high degree of completely cyclized benzimidazobenzophenanthroline structure. Less vigorous reaction conditions gave polymers with lower solution viscosities which appeared to be less highly cyclized. Low‐viscosity polymer was also prepared from DAB and NTCA by solid‐phase polycondensation. Some advancements in the solution viscosities of polymers synthesized from DAB in PPA were caused by second staging in the solid phase.