Continuous process for making polymers in carbon dioxide

A method for carrying out the continuous polymerization of a monomer in a carbon dioxide reaction medium, said method comprising the steps of:

• (a) providing an apparatus including a continuous reaction vessel, a first separator, and a second separator;
• (b) carrying out a polymerization reaction in said reaction vessel by combining a monomer, an initiator, and a carbon dioxide reaction medium therein, wherein said reaction medium comprises liquid or supercritical carbon dioxide, and wherein said reaction produces a solid polymer product in said reaction vessel;
• then
• (c) withdrawing a continuous effluent stream from said reaction vessel during said polymerization reaction, passing said effluent stream through said first separator while maintaining said effluent stream as a liquid or supercritical fluid and separating said solid polymer therefrom;
• and then returning said effluent stream to said reaction vessel;
• and then
• (d) withdrawing a continuous effluent stream from said reaction vessel during said polymerization reaction, passing said effluent stream through said second separator while maintaining said effluent stream as a liquid or supercritical fluid and separating said solid polymer therefrom, and then returning at least a portion of said effluent stream to said reaction vessel, while concurrently removing said solid polymer separated in said first separator during said withdrawing step (c).

A method for carrying out the continuous polymerization of a monomer in a carbon dioxide reaction medium, said method comprising the steps of:

• (a) providing an apparatus including a continuous reaction vessel and a separator wherein said reaction vessel is configured to provide a cumulative exit age distribution (F) of from about 0.45 to about 0.70 when Θ=1;
• (b) carrying out a polymerization reaction in said reaction vessel by combining a monomer, an initiator, and a carbon dioxide reaction medium therein, wherein said reaction medium comprises liquid or supercritical carbon dioxide, and wherein said reaction produces a solid polymer product in said reaction vessel;
• then
• (c) withdrawing a continuous effluent stream from said reaction vessel during said polymerization reaction, wherein said continuous effluent stream is maintained as a liquid or supercritical fluid;
• then
• (d) passing said continuous effluent stream through said separator and separating said solid polymer therefrom while maintaining said effluent stream as a liquid or supercritical fluid;
• and then
• (e) returning at least a portion of said continuous effluent stream to said reaction vessel while maintaining said effluent stream as a liquid or supercritical fluid at a pressure not more than about 100 psi less than the pressure in said reaction vessel, whereby the need for significant recompression of said continuous effluent stream prior to return to said reaction vessel is minimized.

A method for carrying out the continuous polymerization of a monomer in a carbon dioxide reaction medium, said method comprising the steps of:

• (a) providing an apparatus including a continuous reaction vessel and a separator, wherein said reaction vessel is a continuous loop reactor;
• (b) carrying out a polymerization reaction in said reaction vessel by combining a monomer, an initiator, and a carbon dioxide reaction medium therein, wherein said reaction medium comprises liquid or supercritical carbon dioxide, and wherein said reaction produces a solid polymer product in said reaction vessel;
• then
• c) withdrawing a continuous effluent stream from said reaction vessel during said polymerization reaction, wherein said continuous effluent stream is maintained as a liquid or supercritical fluid;
• then
• d) passing said continuous effluent stream through said separator and separating said maintaining said effluent stream as a liquid or supercritical fluid;
• and then
• e) returning at least a portion of said continuous effluent stream to said reaction vessel while maintaining said effluent stream as a liquid or supercritical fluid at a pressure not more than about 100 psi less than the pressure in said reaction vessel, whereby the need for significant recompression of said continuous effluent stream prior to return to said reaction vessel is minimized.