Patent ID: 7683122

Claim:
A process for preparing a poly(1,4-(2,5-dihydroxy)phenylene-2,6-pyrido[2,3-d:5,6-d′]bisimidazole polymer comprising: contacting a molar excess of a 2,3,5,6-tetraamino pyridine free base in water with a 2,5-dihydroxy terephthalic acid salt to form an aqueous mixture, adjusting the pH of the aqueous mixture to within the range of from about 3 to about 5 to precipitate a monomer complex composed of 2,3,5,6-tetraamino pyridine and 2,5-dihydroxy terephthalic acid monomers, contacting, in polyphosphoric acid, the monomer complex with about 0.05 to about 0.9 weight percent metal powder based on the total weight of the monomers, and polymerizing the monomer complex in polyphosphoric acid to form the polymer.