Methods of controlling molecular weight distribution of polymers and compositions thereof
A catalyst, co-catalyst, and/or chain transfer agent is added at a time after initiation of an addition polymerization reaction to produce a polymer product with a widened molecular weight distribution relative to having all of the components in the original reaction mixture. The catalyst, co-catalyst, or chain transfer agent may be added discretely or continuously to the reaction to produce a product with a bimodal, trimodal, or other broadened molecular weight distribution.
1. An aliphatic polycarbonate product of an addition polymerization reaction of carbon dioxide and at least one epoxide made by a method that broadens a molecular weight distribution of the aliphatic polycarbonate product, the method comprising the steps of:
a) starting the addition polymerization reaction at a start time with monomer of the aliphatic polycarbonate product; and
b) adding at least one reaction component to the reaction during at least one reaction time after the start time.
2. An aliphatic polycarbonate having a predetermined molecular weight distribution that is a product of an addition polymerization reaction of carbon dioxide and at least one epoxide made by a method comprising the steps of:
a) determining an initial condition for the reaction;
b) calculating at least one addition amount of at least one reaction component to be added to the reaction during at least one reaction time after a start time for the reaction using at least one rate constant for the reaction;
c) starting the reaction with the initial condition at the start time; and
d) adding the addition amount of the reaction component to the reaction during the reaction time;
wherein the reaction component is selected from the group consisting of:
i) at least one catalyst;
ii) at least one co-catalyst;
iii) at least one reversible chain transfer agent; and
iv) any combination of i), ii), and iii).
3. The aliphatic polycarbonate product of claim 1 , wherein the reaction component is selected from the group consisting of:
i) at least one catalyst;
ii) at least one co-catalyst;
iii) at least one chain transfer agent; and
iv) any combination of i), ii), and iii).
4. The aliphatic polycarbonate product of claim 1 , wherein the reaction component comprises at least one metal-based catalyst selected from the group consisting of:
A) an aluminum-based catalyst;
B) a manganese-based catalyst;
C) a chromium-based catalyst;
D) a cobalt-based catalyst;
E) a yttrium-based catalyst;
F) a zinc-based catalyst;
G) a cadmium-based catalyst;
H) a nickel-based catalyst; and
I) any combination of A) through H).
5. The aliphatic polycarbonate product of claim 1 , wherein the reaction component comprises a cobalt-based catalyst for the co-polymerization of carbon dioxide and the epoxide.
6. The aliphatic polycarbonate product of claim 1 , wherein the reaction component comprises a chromium-based catalyst for the co-polymerization of carbon dioxide and the epoxide.
7. The aliphatic polycarbonate product of claim 1 , wherein the reaction component comprises a zinc-based catalyst for the co-polymerization of carbon dioxide and the epoxide.
8. The aliphatic polycarbonate product of claim 1 , wherein the reaction component comprises at least one chain transfer agent.
9. The aliphatic polycarbonate product of claim 8 , wherein the chain transfer agent comprises an alcohol.
10. The aliphatic polycarbonate product of claim 9 , wherein the alcohol comprises a polyol.
11. The aliphatic polycarbonate product of claim 1 , wherein the reaction component is added continuously to the reaction.
12. The aliphatic polycarbonate product of claim 11 , wherein the reaction component comprises a catalyst added throughout the addition polymerization reaction.
13. The aliphatic polycarbonate product of claim 12 , wherein the reaction component further comprises at least one chain transfer agent.
14. The aliphatic polycarbonate product of claim 13 , wherein the chain transfer agent comprises at least one alcohol.
15. The aliphatic polycarbonate product of claim 14 , wherein the alcohol comprises a polyol.
16. The aliphatic polycarbonate product of claim 11 , wherein a rate of continuous addition is varied with time.
17. The aliphatic polycarbonate product of claim 1 , wherein the addition polymerization is a co-polymerization of carbon dioxide and propylene oxide.
18. The aliphatic polycarbonate product of claim 1 , wherein the reaction component is added in one or more discrete steps to the reaction.
19. The aliphatic polycarbonate product of claim 1 , wherein the reaction component is added in a single step such that the molecular weight distribution is bimodal.
20. The aliphatic polycarbonate product of claim 1 , wherein the addition polymerization reaction is a batch polymerization reaction.
21. The aliphatic polycarbonate of claim 2 , wherein the reaction component comprises at least one metal-based catalyst selected from the group consisting of:
A) an aluminum-based catalyst;
B) a manganese-based catalyst;
C) a chromium-based catalyst;
D) a cobalt-based catalyst;
E) a yttrium-based catalyst;
F) a zinc-based catalyst;
G) a cadmium-based catalyst;
H) a nickel-based catalyst; and
I) any combination of A) through H).
22. The aliphatic polycarbonate of claim 2 , wherein the reaction component comprises a cobalt-based catalyst for the co-polymerization of carbon dioxide and the epoxide.
23. The aliphatic polycarbonate of claim 2 , wherein the reaction component comprises a chromium-based catalyst for the co-polymerization of carbon dioxide and the epoxide.
24. The aliphatic polycarbonate of claim 2 , wherein the reaction component comprises a zinc-based catalyst for the co-polymerization of carbon dioxide and the epoxide.
25. The aliphatic polycarbonate of claim 2 , wherein the reaction component comprises at least one chain transfer agent.
26. The aliphatic polycarbonate of claim 25 , wherein the chain transfer agent comprises an alcohol.
27. The aliphatic polycarbonate of claim 26 , wherein the alcohol comprises a polyol.
28. The aliphatic polycarbonate of claim 2 , wherein the reaction component is added continuously to the reaction.
29. The aliphatic polycarbonate of claim 28 , wherein the reaction component comprises a catalyst added throughout the addition polymerization reaction.
30. The aliphatic polycarbonate of claim 29 , wherein the reaction component further comprises at least one chain transfer agent.
31. The aliphatic polycarbonate of claim 30 , wherein the chain transfer agent comprises an alcohol.
32. The aliphatic polycarbonate of claim 31 , wherein the alcohol comprises a polyol.
33. The aliphatic polycarbonate of claim 28 , wherein a rate of continuous addition is varied with time.
34. The aliphatic polycarbonate of claim 2 , wherein the addition polymerization is a co-polymerization of carbon dioxide and propylene oxide.
35. The aliphatic polycarbonate of claim 2 , wherein the reaction component is added in one or more discrete steps to the reaction.
36. The aliphatic polycarbonate of claim 2 , wherein the reaction component is added in a single step such that the molecular weight distribution is bimodal.
37. The aliphatic polycarbonate of claim 2 , wherein the addition polymerization reaction is a batch polymerization reaction.