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. A method of broadening a molecular weight distribution of a polymer product of an addition polymerization reaction comprising the steps of:
a) starting the addition polymerization reaction at a start time with monomer of the polymer product; and
b) adding at least one reaction component to the reaction during at least one reaction time after the start 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).
2. The method of claim 1 , wherein the catalyst 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).
3. The method of claim 1 , wherein the reaction component is added continuously to the reaction.
4. The method of claim 3 , wherein a rate of continuous addition is varied with time.
5. The method of claim 1 , wherein the product of the addition polymerization reaction is a polycarbonate.
6. The method of claim 5 , wherein the addition polymerization is a co-polymerization of carbon dioxide and an epoxide.
7. The method of claim 6 , wherein the addition polymerization is a co-polymerization of carbon dioxide and propylene oxide.
8. The method of claim 1 , wherein the reaction component is added in one or more discrete steps to the reaction.
9. The method of claim 1 , wherein the reaction component is added in a single step such that the molecular weight distribution of the product is bimodal.
10. The method of claim 1 , wherein the reaction component is added in two steps such that the molecular weight distribution of the product is trimodal.
11. The method of claim 1 further comprising adding a chain termination agent prior to an end time when the reaction is stopped.
12. A product made by the method of claim 1 .
13. A method of broadening a molecular weight distribution of a polycarbonate product of an addition polymerization reaction comprising the steps of:
a) starting the addition polymerization reaction at a start time with monomer of the polycarbonate product; and
b) adding at least one reaction component to the reaction during at least one reaction time after the start time.
14. The method of claim 13 , 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).
15. The method of claim 14 , wherein the catalyst 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).
16. The method of claim 13 , wherein the reaction component is added continuously to the reaction.
17. The method of claim 16 , wherein a rate of continuous addition is varied with time.
18. The method of claim 13 , wherein the addition polymerization is a co-polymerization of carbon dioxide and an epoxide.
19. The method of claim 18 , wherein the addition polymerization is a co-polymerization of carbon dioxide and propylene oxide.
20. The method of claim 13 , wherein the reaction component is added in one or more discrete steps to the reaction.
21. The method of claim 13 , wherein the reaction component is added in a single step such that the molecular weight distribution is bimodal.
22. The method of claim 13 , wherein the reaction component is added in two steps such that the molecular weight distribution is trimodal.
23. A method of synthesizing a polymer product of an addition polymerization reaction having a predetermined molecular weight distribution, the 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).
24. The method of claim 23 , wherein the catalyst 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).
25. The method of claim 23 , wherein the reaction component is added continuously to the reaction.
26. The method of claim 23 , wherein the product of the addition polymerization reaction is a polycarbonate.
27. The method of claim 26 , wherein the addition polymerization is a co-polymerization of carbon dioxide and an epoxide.
28. The method of claim 27 , wherein the addition polymerization is a co-polymerization of carbon dioxide and propylene oxide.
29. The method of claim 23 , wherein the reaction component is added in one or more discrete steps to the reaction.
30. The method of claim 23 , wherein the reaction component is added in a single step such that the molecular weight distribution is bimodal.
31. The method of claim 23 , wherein the reaction component is added in two steps such that the molecular weight distribution is trimodal.
32. The method of claim 23 further comprising adding a chain termination agent prior to an end time when the reaction is stopped.