Processes for preparing high inherent viscosity polyareneazoles using metal powders

1. A process for preparing a polyareneazole polymer comprising:

contacting, in polyphosphoric acid, azole-forming monomers and from about 0.05 to about 0.9 weight percent, based on the total weight of the azole-forming monomers, iron metal powder, and

reacting the azole-forming monomers to form the polyareneazole polymer.

2. The process of claim 1 wherein the polyareneazole polymer is characterized as providing a polymer solution having an inherent viscosity of at least about 22 dl/g at 30° C. at a polymer concentration of 0.05 g/dl in methane sulfonic acid.

3. The process of claim 1 wherein the amount of iron metal powder is in the range of from about 0.1 to about 0.5 weight percent.

4. The process of claim 1 wherein the polyareneazole is a polypyridoazole.

5. The process of claim 4 wherein the polypyridoazole is a polypyridobisimidazole.

6. The process of claim 5 wherein the polypyridobisimidazole is poly(1,4-(2,5-dihydroxy)phenylene-2,6-pyrido[2,3-d:5,6-d′]bisimidazole).

7. The process of claim 1 wherein the azole-forming monomers include 2,5-dimercapto-p-phenylene diamine, terephthalic acid, bis-(4-benzoic acid), oxy-bis-(4-benzoic acid), 2,5-dihydroxyterephthalic acid, isophthalic acid, 2,5-pyridodicarboxylic acid, 2,6-napthalenedicarboxylic acid, 2,6-quinolinedicarboxylic acid, 2,6-bis(4-carboxyphenyl) pyridobisimidazole, 2,3,5,6-tetraaminopyridine, 4,6-diaminoresorcinol, 2,5-diaminohydroquinone, 2,5-diamino-4,6-dithiobenzene, or any combination thereof.

8. The process of claim 7 , wherein the azole-forming monomers include 2,3,5,6-tetraaminopyridine and 2,5-dihydroxyterephthalic acid.

9. A process for preparing a polyareneazole polymer comprising:

contacting, in polyphosphoric acid, azole-forming monomers and metal powder including vanadium metal, chromium metal, or any combination thereof, the metal powder added in an amount of from about 0.05 to about 0.9 weight percent, based on the total amount of azole-forming monomers, and

reacting the monomers to form the polyareneazole polymer.

10. The process of claim 9 wherein the polymer is characterized as providing a polymer solution having an inherent viscosity of at least about 22 dl/g at 30° C. at a polymer concentration of 0.05 g/dl in methane sulfonic acid.

11. The process of claim 9 wherein the amount of metal powder is in the range of from about 0.1 to about 0.5 weight percent.

12. The process of claim 9 wherein the polyareneazole is poly(1,4-(2,5-dihydroxy) phenylene-2,6-pyrido[2,3-d:5,6-d′]bisimidazole).

13. The process of claim 9 , wherein the azole-forming monomers include 2,5-dimercapto-p-phenylene diamine, terephthalic acid, bis-(4-benzoic acid), oxy-bis-(4-benzoic acid), 2,5-dihydroxyterephthalic acid, isophthalic acid, 2,5-pyridodicarboxylic acid, 2,6-napthalenedicarboxylic acid, 2,6-quinolinedicarboxylic acid, 2,6-bis(4-carboxyphenyl) pyridobisimidazole, 2,3,5,6-tetraaminopyridine, 4,6-diaminoresorcinol, 2,5-diaminohydroquinone, 2,5-diamino-4,6-dithiobenzene, or any combination thereof.

14. The process of claim 13 , wherein the azole-forming monomers include 2,3,5,6-tetraaminopyridine and 2,5-dihydroxyterephthalic acid.

15. A process for preparing a polyareneazole polymer, comprising:

contacting, in polyphosphoric acid, azole-forming monomer complex and tin metal powder, the azole-forming monomer complex synthesized using a molar excess of a first azole-forming monomer relative to a second azole-forming monomer, the monomer complex comprising a 1:1 molar ratio of the first azole-forming monomer relative to the second azole-forming monomer, the tin metal powder added in an amount of from about 0.1 to about 0.5 weight percent, based on the total amount of azole-forming monomer complex, and

reacting the monomer complex to form the polyareneazole polymer.

16. The process of claim 15 wherein the polyareneazole polymer is characterized as providing a polymer solution having an inherent viscosity of at least about 22 dl/g at 30° C. at a polymer concentration of 0.05 g/dl in methane sulfonic acid.

17. The process of claim 15 wherein the polyareneazole is poly(1,4-(2,5-dihydroxy)phenylene-2,6-pyrido[2,3-d:5,6-d′]bisimidazole).

18. The process of claim 15 wherein the first and second azole-forming monomers include 2,5-dimercapto-p-phenylene diamine, terephthalic acid, bis-(4-benzoic acid), oxy-bis-(4-benzoic acid), 2,5-dihydroxyterephthalic acid, isophthalic acid, 2,5-pyridodicarboxylic acid, 2,6-napthalenedicarboxylic acid, 2,6-quinolinedicarboxylic acid, 2,6-bis(4-carboxyphenyl)pyridobisimidazole, 2,3,5,6-tetraaminopyridine, 4,6-diaminoresorcinol, 2,5-diaminohydroquinone, 2,5-diamino-4,6-dithiobenzene, or any combination thereof.

19. The process of claim 18 , wherein the first azole-forming monomer is 2,3,5,6-tetraaminopyridine and the second azole-forming monomer is 2,5-dihydroxyterephthalic acid.