Granted Patent B2

US 8,952,126 · App. 13/938,874 · Granted Feb 10, 2015

Abstract

Claims (61)

1. A method of purifying a block copolymer comprising:

heating a solution containing a crude block copolymer and an alcohol;

cooling the solution to promote precipitation of a purified block copolymer; and

isolating the purified block copolymer, wherein isolating the purified block copolymer comprises filtering the solution to separate the purified block copolymer from a filtrate and recovering unreacted monomer and catalyst from the filtrate,

and further wherein:

an amount of impurities remaining in the purified block copolymer is from about 0 to about 5 wt % based on a total weight of the purified block copolymer;

a ratio of a polydispersity index of the crude block copolymer to a polydispersity index of the purified block copolymer is from about 1.02 to about 1.25;

a ratio of a molecular weight of the crude block copolymer to a molecular weight of the purified block copolymer is from about 0.75 to about 1.0; and

a ratio of a number average molecular weight of the crude block copolymer to a number average molecular weight of the purified block copolymer is from about 0.65 to about 1.

2. The method of claim 1 , wherein the block copolymer is a functionalized block copolymer of a polyester/polycarbonate hybrid.

3. The method of claim 2 , wherein the block copolymer is a polycaprolactone-b-polycarbonate-b-polylactide block copolymer.

4. The method of claim 1 , wherein the alcohol is methanol.

5. The method of claim 1 , wherein the solution is heated to a temperature of from about 50° C. to about 120° C.

6. The method of claim 1 , wherein the solution is cooled to a temperature of from about −30° C. to about 10° C.

7. A method of making a block copolymer comprising:

forming a crude block copolymer;

heating a solution containing the crude block copolymer and alcohol;

cooling the solution to promote precipitation of a purified block copolymer; and

isolating the purified block copolymer, wherein isolating the purified block copolymer comprises filtering the solution to separate the purified block copolymer from a filtrate and recovering unreacted monomer and catalyst from the filtrate,

and further wherein:

an amount of impurities remaining in the purified block copolymer is from about 0 to about 5 wt % based on a total weight of the purified block copolymer;

a ratio of a polydispersity index of the crude block copolymer to a polydispersity index of the purified block copolymer is from about 1.02 to about 1.25,

a ratio of a molecular weight of the crude block copolymer to a molecular weight of the purified block copolymer is from about 0.75 to about 1.0; and

a ratio of a number average molecular weight of the crude block copolymer to a number average molecular weight of the purified block copolymer is from about 0.65 to about 1.0.

8. The method of claim 7 , wherein forming the crude block copolymer comprises a one-pot, organocatalytic, neat ring-opening polymerization.

9. The method of claim 8 further comprising polymerizing the mixture to form a block copolymer, wherein the polymerization comprises:

sequentially adding monomers to a reactor to form a mixture;

capping the mixture with succinic anhydride; and

cooling the mixture to room temperature to form the crude block copolymer.

10. The method of claim 9 , wherein sequentially adding monomers comprises:

adding ε-caprolactone, and a catalyst to the reactor to form a first reaction mixture;

heating the first reaction mixture;

polymerizing a first block;

adding a functionalized carbonate monomer to the reactor to form a second reaction mixture;

polymerizing a second block;

adding D,L-lactide to the reactor to form a third reaction mixture; and

polymerizing a third block.

11. The method of claim 7 , wherein the block copolymer is a functionalized block copolymer of a polyester/polycarbonate hybrid.

12. The method of claim 11 , wherein the block copolymer is a polycaprolactone-b-polycarbonate-b-polylactide block copolymer.

13. The method of claim 7 , wherein the alcohol is methanol.

14. The method of claim 7 , wherein the solution is heated to a temperature of from about 50° C. to about 120° C.

15. A one-pot method of making an ABC tri-block copolymer, the method comprising:

adding ε-caprolactone, hexanol, and a catalyst to a reactor vessel to form a first reaction mixture;

heating the first reaction mixture at a temperature within a range of from about 125° C. to about 145° C. for about 36 to about 72 hours to ring-open and polymerize the ε-caprolactone, forming a reaction mixture comprising an A block polymer;

adding a functionalized carbonate monomer to the reaction mixture comprising the A block polymer to form a second reaction mixture;

maintaining the second reaction mixture at a temperature within a range of from about 125° C. to about 145° C. for about 20 to about 40 minutes to ring-open and polymerize the functionalized carbonate monomer with the A block, forming a reaction mixture comprising an AB block copolymer;

adding D,L-lactide to the reaction mixture comprising the AB block copolymer to form a third reaction mixture;

maintaining the third reaction mixture at a temperature within a range of from about 125° C. to about 145° C. for about 20 to about 40 minutes to ring-open and polymerize the D,L-lactide with the AB block copolymer, forming a reaction mixture comprising an ABC tri-block copolymer;

adding succinic anhydride to the reaction mixture comprising the ABC tri-block copolymer to form a fourth reaction mixture;

maintaining the fourth reaction mixture at a temperature within a range of from about 125° C. to about 145° C. for about 2 to about 12 minutes to cap the ABC tri-block copolymer with the succinic anhydride to form a clear melt comprising a capped ABC tri-block copolymer;

cooling the clear melt to room temperature to form a crude solid;

adding methanol to the crude solid to form a solution;

heating the solution containing the crude solid and methanol to a temperature of from about 130° C. to about 140° C. and refluxing for about 0.1 to about 1 hours;

cooling the refluxed solution to a temperature of from about −30° C. to about 10° C. for about 8 to about 20 hours; and

isolating a solid from the cooled reflux solution to obtain a purified capped ABC tri-block copolymer;

wherein:

the purified copolymer is a polycaprolactone-b-polycarbonate-b-polylactide block copolymer;

a ratio of a polydispersity index of the crude solid to a polydispersity index of the purified copolymer is from about 1.02 to about 1.25;

a ratio of a molecular weight of the crude solid to a molecular weight of the purified block copolymer is from about 0.75 to about 1.0;

a ratio of a number average molecular weight of the crude solid to a number average molecular weight of the purified copolymer is from about 0.65 to about 1.0; and

an amount of impurities remaining in the purified copolymers is from about 0 to about 5 wt % based on a total weight of the purified copolymer.

Assignments (11)