Polycarbonate polyol compositions and methods
In one aspect, the present disclosure encompasses polymerization systems for the copolymerization of CO 2 and epoxides comprising 1) a catalyst including a metal coordination compound having a permanent ligand set and at least one ligand that is a polymerization initiator, and 2) a chain transfer agent having two or more sites that can initiate polymerization. In a second aspect, the present disclosure encompasses methods for the synthesis of polycarbonate polyols using the inventive polymerization systems. In a third aspect, the present disclosure encompasses polycarbonate polyol compositions characterized in that the polymer chains have a high percentage of —OH end groups and a high percentage of carbonate linkages. The compositions are further characterized in that they contain polymer chains having an embedded polyfunctional moiety linked to a plurality of individual polycarbonate chains.
1. A polycarbonate polyol composition comprising an epoxide CO 2 copolymer characterized in that the copolymer has:
an Mn between 400 and 20,000 g/mol,
greater than 90% carbonate linkages, and
wherein the composition comprises:
polymer chains denoted P 1 having the formula T-Y-A-(Y-T) n , derived from a chain transfer agent having a formula Y-A-(Y) n , wherein:
each -T is a polycarbonate chain having a formula independently selected from the group consisting of:
wherein:
each E is independently an optionally substituted C 2 unit derived from an epoxide or a mixture of two or more epoxides;
p ranges from 5 to 10,000; and
each chain transfer agent of formula Y-A-(Y) n comprises two or more sites capable of initiating chain growth in the co-polymerization of an epoxide and carbon dioxide;
—Y group is independently a functional group capable of initiating chain growth of epoxide CO 2 copolymers and each Y group is the same or different,
-A- is a covalent bond or a multivalent moiety; and
n is an integer between 1 and 10 inclusive;
wherein the composition is characterized in that more than 97% of the epoxide CO 2 copolymer chains are of type P 1 .
2. The polycarbonate polyol composition of claim 1 , comprising greater than 95% carbonate linkages.
3. The polycarbonate polyol composition of claim 1 , comprising greater than 99% carbonate linkages.
4. The polycarbonate polyol composition of claim 1 , having an Mn between about 500 and about 5,000 g/mol.
5. The polycarbonate polyol composition of claim 1 , having an Mn between about 1,000 and about 3,000 g/mol.
6. The polycarbonate polyol composition of claim 1 , further comprising polymer chains denoted P 2 having a formula selected from the group consisting of:
wherein
X is a bound form of an anion capable of initiating only one polymer chain;
wherein the ratio of P 1 polymer chains to P 2 polymer chains is greater than 40:1.
7. The polycarbonate polyol composition of claim 6 , wherein the ratio of P 1 polymer chains to P 2 polymer chains is greater than 100:1.
8. The polycarbonate polyol composition of claim 1 , further comprising polymer chains denoted P 1a having a formula:
9. The polycarbonate polyol composition of claim 1 , wherein each E is
where, R 21 , R 22 , R 23 , and R 24 , are each independently selected from the group consisting of: —H; and an optionally substituted group selected from C 1-30 aliphatic; C 6-14 aryl; 3- to 12-membered heterocycle, and 5- to 12-membered heteroaryl, where any two or more of R 21 , R 22 , R 23 , and R 24 can be taken together with intervening atoms to form one or more optionally substituted 3- to 12-membered rings, optionally containing one or more heteroatoms.
10. The polycarbonate polyol composition of claim 9 , wherein -E- is selected from the group consisting of:
and mixtures of any two or more of these,
wherein R x is selected from optionally substituted aliphatic, fluorinated aliphatic, optionally substituted heteroaliphatic, optionally substituted aryl, fluorinated aryl, or optionally substituted heteroaryl.
11. The polycarbonate polyol composition of claim 9 , wherein -E- comprises predominantly —CH 2 CH 2 — units derived from ethylene oxide.
12. The polycarbonate polyol composition of claim 9 , wherein -E- comprises predominantly —CH 2 CH(CH 3 )— units derived from propylene oxide.
13. The polycarbonate polyol composition of claim 1 , where chains of type P 1 have the formula:
14. The polycarbonate polyol composition of claim 1 , where chains of type P 1 have the formula:
15. The polycarbonate polyol composition of claim 1 , where chains of type P 1 have the formula:
16. The polycarbonate polyol composition of claim 1 , wherein chains of type P 1 have the formula:
where each z is independently 0 or 1.
17. A polyurethane composition formed by reaction of one or more isocyanates with one or more aliphatic polycarbonate polyols of claim 1 .
18. An article of manufacture comprising the polycarbonate polyol composition of claim 1 .
19. An article of manufacture comprising the polycarbonate polyol composition of claim 1 .
20. The polycarbonate polyol composition of claim 1 , wherein the composition is characterized in that more than 99% of the epoxide CO 2 copolymer chains are of type P 1 .