Claims
- 1. A method for preparing thin films of rigid-rod, aromatic heterocyclic benzobisazole polymers and co-polymers which comprises
- (a) preparing a 0.1 to 5.0 weight percent solution of the rigid-rod polymer or co-polymer in a suitable solvent;
- (b) forming a film from the solution;
- (c) exposing the film to a non-solvent vapor for about 1 to 5 minutes per micron thickness in the finished film;
- (d) quenching the film in a non-solvent; and
- (e) recovering the finished film.
- 2. The method of claim 1 wherein said polymer is a benzobisoxazole polymer.
- 3. The method of claim 1 wherein said polymer is a benzobisthiazole polymer.
- 4. The method of claim 1 wherein said polymer is a benzobisimidazole polymer.
- 5. The method of claim 1 wherein said polymer is a poly(p-phenylene benzobisazole).
- 6. The method of claim 1 wherein said polymer is a poly(4,4'-biphenylene benzobisazole).
- 7. The method of claim 1 wherein said solvent is methanesulfonic acid.
- 8. The method of claim 1 wherein said solvent is polyphosphoric acid.
- 9. The method of claim 1 wherein said solvent is concentrated sulfuric acid.
- 10. The method of claim 1 wherein said non-solvent is water.
- 11. The method of claim 1 wherein the film formed in step (b) has a thickness of about 50 to 500 microns.
- 12. The method of claim 1 wherein the film formed in step (b) is exposed to said non-solvent vapor in step (c) for about 1.5 to 3 minutes per micron thickness in the finished film.
- 13. The method of claim 1 wherein said polymer is a benzobisazole co-polymer.
- 14. A method for preparing thin films of a blend of rigid-rod, aromatic heterocyclic benzobisazole polymers and co-polymers and flexible, coil-like aromatic heterocyclic benzobisazole polymers and co-polymers, which comprises
- (a) preparing a 0.1 to 5.0 weight percent solution of the blend in a suitable solvent;
- (b) forming a film from the solution;
- (c) exposing the film to a non-solvent vapor for about 1 to 5 minutes per micron thickness in the finished film;
- (d) quenching the film in a non-solvent; and
- (e) recovering the finished film,
- wherein the weight ratio of rigid-rod polymer or co-polymer to flexible polymer or co-polymer is about 5:95 to 60:40.
RIGHTS OF THE GOVERNMENT
The invention described herein may be manufactured and used by or for the Government of the United States for all governmental purposes without the payment of any royalty.
US Referenced Citations (8)