Ring-opening polymerization methods and recyclable biorenewable polyesters
The invention provides polymers of Formulas I-III, such as polyesters and unsaturated polyesters, and crosslinked and copolymerized polymers thereof. The invention also provides methods to catalytically ring-open five-membered rings such lactones, lactams, and thiolactones, as via ring-opening polymerization. The polymerization products are recyclable and can be depolymerized back to their monomer form via thermolysis and acid or base catalysis.
1. A polymer of Formula II:
wherein
X is O, S, or NR a wherein R a is H, alkyl, or aryl;
R 1 is H, alkyl, aryl, methylene (═CH 2 ), or substituted methylene (═CR 2 where each R is independently H, alkyl, aryl, substituted alkyl, or substituted aryl);
R 2 is H, alkyl, or aryl;
R 3 is H, alkyl, or aryl; and
n is about 5 to about 1,000.
2. The polymer of claim 1 wherein n is about 50 to about 300.
3. The polymer of claim 1 wherein X is O.
4. The polymer of claim 1 wherein R 1 is methyl.
5. The polymer of claim 1 wherein R 2 is methyl.
6. The polymer of claim 1 wherein R 3 is methyl.
7. The polymer of claim 1 wherein two of R 1 -R 3 are H.
8. The polymer of claim 1 wherein R 1 is methylene or substituted methylene.
9. The polymer of claim 1 wherein R 1 is methylene and one or more moieties of the polymer are crosslinked by photocuring or functionalized by thiol-ene reaction.
10. The polymer of claim 1 wherein the polymer is a polymer of Formula III:
wherein n is about 10 to about 300.
11. A polymer comprising Formula V:
wherein
X is O, S, or NR a wherein R a is H, alkyl, or aryl;
R 1 is H, alkyl, aryl, methylene (═CH 2 ), or substituted methylene (═CR 2 where each R is independently H, alkyl, aryl, substituted alkyl, or substituted aryl);
R 2 is H, alkyl, or aryl;
R 3 is H, alkyl, or aryl; and
n is about 50 to about 1,000.
12. The polymer of claim 11 wherein the polymer is a polymer of Formula VI:
wherein
R 2 is H and R 3 is Me;
R 2 is Me and R 3 is H; or
R 2 and R 3 are both H;
wherein
the polymer may be crosslinked by photocuring or functionalized by a thiol-ene reaction.
13. A random copolymer prepared by ring opening copolymerization of a lactone and a compound of Formula X:
wherein
X is O, S, or NR a wherein R a is H, alkyl, or aryl;
R 1 is H, alkyl, aryl, methylene (═CH 2 ), or substituted methylene (═CR 2 where each R is independently H, alkyl, aryl, substituted alkyl, or substituted aryl);
R 2 is H, alkyl, or aryl;
R 3 is H, alkyl, or aryl;
in the presence of a ring-opening catalyst to provide the resulting random copolymer having a number average molecular weight of at least 10 kDa.
14. The copolymer of claim 13 wherein X is O.
15. The copolymer of claim 13 wherein the compound of Formula X is selected from the group consisting of:
16. A method comprising polymerizing a compound of Formula X by ring-opening polymerization:
wherein
X is O, S, or NR a wherein R a is H, alkyl, or aryl;
R 1 is H, Me, methylene (═CH 2 ), or substituted methylene (═CR 2 where each R is independently H, alkyl, aryl, substituted alkyl, or substituted aryl);
R 2 is H or Me;
R 3 is H or Me;
wherein the polymerization is carried out at about 1 atm and at less than about 25° C. in the presence of a ring-opening catalyst, wherein the ring opening catalyst is a lanthanide homoleptic complex; a yttrium heteroleptic complex; an organometallic catalyst comprising Li, Mg, or Zn; a strong organic base; or an inorganic base;
to provide the resulting ring opened polymer in the form of a linear polymer or cyclic polymer.
17. The method of claim 16 wherein the ring-opening polymerization is carried out under conditions that cause the polymerization product to crystallize or precipitate out of solution during the polymerization.
18. The method of claim 16 wherein the ring-opening catalyst is a lanthanide complex of Formula A:
wherein Ln is La, Y, or Sm, or
a yttrium complex of Formula B:
wherein X is N(SiHMe) 2 or CH 2 SiMe 3 .
19. The method of claim 16 wherein the reaction conditions further comprise a protic initiator.
20. The method of claim 16 wherein the ring-opening catalyst is an organometallic catalyst comprising Li, Mg, or Zn selected from RLi, MgR 2 , LM-X wherein M is Mg or Zn, L is an anionic ligand, and X is R, OR, SR, or NR 2 , Al(OR) 3 , and L 2 AlOR wherein L is an anionic ligand, wherein R is alkyl, aryl, substituted alkyl, or substituted aryl.
21. The method of claim 16 wherein the ring-opening polymerization is carried out below 0° C.
22. The method of claim 16 wherein:
R 1 is H, Me, or methylene (═CH 2 );
R 2 is H or Me; and
R 3 is H or Me.
23. The method of claim 16 wherein the compound of Formula X is selected from the group consisting of: