Methods for the purification of polymers

A method of purifying a polymer containing impurities, the method comprising:

• dissolving the polymer containing impurities in an organic solvent to form an organic polymer solution;
• simultaneously, but separately, co-introducing the organic polymer solution and an anti-solvent into an extraction vessel in concurrent flow streams while the anti-solvent is maintained in a supercritical state to extract the organic solvent and impurities from the organic solution and thereby form a plasticized polymer melt, the polymer being plasticized by the supercritical anti-solvent;
• and
• extruding the plasticized polymer melt from the extraction vessel into an accumulation vessel to separate the same from the anti-solvent containing the organic solvent and impurities.

A method of purifying a polymer containing impurities, the method comprising:

• dissolving the polymer containing impurities in an organic solvent to form an organic polymer solution;
• simultaneously, but separately, co-introducing the organic polymer solution and an anti-solvent into an extraction vessel in counter-current flow streams while the anti-solvent is maintained in a supercritical state to extract the organic solvent and impurities from the organic solution and thereby form a plasticized polymer melt, the polymer being plasticized by the supercritical anti-solvent;
• venting the anti-solvent containing the organic solvent and impurities from the extraction vessel to allow the plasticized polymer melt to accumulate in the extraction vessel;
• and
• extruding the plasticized polymer melt from the extraction vessel.

A method of purifying a polymer containing impurities, the method comprising:

• dissolving the polymer containing impurities in an organic solvent to form an organic polymer solution;
• simultaneously, but separately, introducing the organic polymer solution and an anti-solvent into an extraction vessel while the anti-solvent is maintained in a supercritical state to extract the organic solvent and impurities from the organic solution and thereby precipitate the polymer in the form of solid particles;
• collecting the solid particles of polymer on a filter in the extraction vessel as the anti-solvent, organic solvent and impurities are removed;
• and
• depressurizing the extraction chamber to recover the solid particles of purified polymer.