Process for preparation of polyolefins via degenerative transfer polymerization
Disclosed is a method of producing a polyolefin composition comprising contacting a metallocene pre-catalyst with a substoichiometric amount of a co-catalyst; adding a first olefin monomer; and polymerizing the first monomer for a time sufficient to form the polyolefin. The method allows for the use of a minimum amount of activating co-catalyst, and allows for the production of stereoregular and non-stereoregular polyolefins. The use of configurationally stable metallocene pre-catalysts allows for the production of monomodal isotactic polyolefins having narrow polydispersity. The use of configurationally unstable metallocene pre-catalysts allows for the production of monomodal atactic polyolefins having narrow polydispersity. The method of the present invention optionally further comprises contacting the polyolefin with a second amount of said co-catalyst; adding a second olefin monomer; polymerizing said second olefin monomer to form a block-polyolefin composition. Also disclosed are monomodal diblock copolymer compositions made according to the present invention.
1. A method of producing a polyolefin composition comprising contacting a metallocene pre-catalyst with a substoichiometric amount of a co-catalyst; adding a first olefin monomer; and polymerizing by degenerative transfer said first monomer for a time sufficient to form said polyolefin.
2. The method of claim 1 , wherein said metallocene pre-catalyst has the formula:
wherein the dotted lines indicate a delocalized bond;
M is Ti, Zr or Hf;
each R 1 is independently hydrogen or alkyl or two adjacent R 1 form an aromatic ring;
each R 2 , R 3 and R 4 is independently alkyl, cycloalkyl, Si(alkyl) 3 , Si(aryl) 3 , phenyl, optionally substituted phenyl, or alkylphenyl; and
each R 5 is halo, alkyl, cycloalkyl, aryl or arylalkyl.
3. The method of claim 2 , wherein:
said optional substituents on phenyl are amino, hydroxy, alkoxy, amide, aryl, alkyl, halo, ketone, ester, —SO 3 H, aldehyde, carboxylic acid, cyano, nitro and ammomium.
4. The method of claim 2 , wherein said metallocene pre-catalyst is 1,2,3,4,5-pentamethylcyclopentadienyl dimethyl zirconium (N-ethyl-N- t butyl-2-methyl)amidinate or 1,2,3,4,5-pentamethylcyclopentadienyl chloro isobutyl zirconium (N-ethyl-N- t butyl-2-methyl)amidinate.
5. The method of claim 1 , wherein said co-catalyst has one of the formulae:
[A] ⊕[BR 6 4 ] ⊖ or BR 6 3
wherein A ⊕ is Si(R 7 ) 3 , a cationic Lewis acid or a cationic BrØnsted acid;
B is the element boron;
R 6 is phenyl or a phenyl optionally substituted by alkoxy, amide, aryl, alkyl, halo, ketone, ester, —SO 3 H, aldehyde, carboxylic acid, cyano, nitro and ammonium;
each R 7 is independently selected from alkyl and optionally substituted phenyl.
6. The method of claim 5 , wherein said co-catalyst is [PhNMe 2 H][B(C 6 F 5 ) 4 ] or Si(CH 2 CH 3 ) 3 [B(C 6 F 5 ) 4 ].
7. The method of claim 1 , wherein said metallocene pre-catalyst and said co-catalyst are contacted in a metallocene pre-catalyst:co-catalyst ratio of 1.1:1–100:1.
8. The method of claim 7 , wherein said metallocene pre-catalyst and said co-catalyst are contacted in a metallocene pre-catalyst:co-catalyst ratio of about 2:1.
9. The method of claim 1 , wherein said co-catalyst is added in an amount of about 1–5 mole % of said metallocene pre-catalyst.
10. The method of claim 1 , wherein said metallocene pre-catalyst is contacted with a substoichiometric amount of a co-catalyst in an inert solvent.
11. The method of claim 10 , wherein said solvent is chlorobenzene, dichlorobenzene, isopentane, hexane, cyclohexane, heptane, benzene, toluene, trifluorotoluene, pentane, octane, isooctane or dichloromethane.
12. The method of claim 1 , wherein said metallocene pre-catalyst and said co-catalyst are contacted at a temperature of about −20° C. to about 10° C.
13. The method of claim 1 , wherein said first olefin monomer is ethene, propene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, styrene, alpha-methyl styrene, butadiene, isoprene, acrylonitrile, methyl acrylate, methyl methacrylate, vinyl acetate, vinyl chloride, vinyl fluoride, vinylidene chloride, N-vinyl pyrrolidone, 3-methylbutene, 3-methyl-1-pentene, vinylcyclohexane, vinylcyclobutane, vinylcyclopentane, vinylcyclooctane, 1-decene, enantiomerically pure β-citronellene, 3,5,5-trimethyl-1-hexene or 4-methyl-1-pentene.
14. The method of claim 1 , wherein said first olefin monomer is a non-conjugated diene having the formula:
wherein X=CH 2 , CO, N(R 13 ), O or S;
R 11 , R 12 and R 13 are each independently H, alkyl or phenyl; and
n and m are each independently an integer from 0–5.
15. The method of claim 1 , wherein said first olefin monomer is 1,4-pentadiene, 1,5-hexadiene, 5-vinyl-2-norbornene, 1,7-octadiene, vinylcyclohexene, dicyclopentadiene, butadiene, isobutylene, isoprene or ethylidene norbornene.
16. The method of claim 1 , wherein said metallocene pre-catalyst and said first olefin monomer are added in a metallocene pre-catalyst:first monomer ratio of about 1:10–1:10,000.
17. The method of claim 16 , wherein said ratio is about 1:10.
18. The method of claim 16 , wherein said ratio is about 1:100.
19. The method of claim 16 , wherein said ratio is about 1:1000.
20. The method of claim 1 , further comprising contacting said polyolefin with a second amount of said co-catalyst; adding a second olefin monomer; and polymerizing said second olefin monomer to form a block-polyolefin composition.
21. The method of claim 20 , wherein said second amount of co-catalyst is about a stoichiometric amount or more of said metallocene pre-catalyst.
22. The method of claim 20 , wherein said second amount is a metallocene pre-catalyst: co-catalyst ratio of about 0.5:1–2:1.
23. The method of claim 20 , wherein said metallocene pre-catalyst and said second olefin monomer are added in a metallocene pre-catalyst:second monomer ratio of about 1:10–1:10,000.
24. The method of claim 23 , wherein said ratio is about 1:10.
25. The method of claim 23 , wherein said ratio is about 1:100.
26. The method of claim 23 , wherein said ratio is about 1:1000.
27. The method of claim 20 , wherein said first olefin and second olefin are independently ethene, propene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, styrene, alpha-methyl styrene, butadiene, isoprene, acrylonitrile, methyl acrylate, methyl methacrylate, vinyl acetate, vinyl chloride, vinyl fluoride, vinylidene chloride, N-vinyl pyrrolidone, 3-methylbutene, 3-methyl-1-pentene, vinylcyclohexane, vinylcyclobutane, vinylcyclopentane, vinylcyclooctane, 1-decene, enantiomerically pure β-citronellene, 3,5,5-trimethyl-1-hexene or 4-methyl-1-pentene.
28. The method of claim 20 , wherein said first olefin monomer and said second olefin monomer are independently non-conjugated dienes having the formula:
wherein X=CH 2 , CO, N(R 13 ), O or S
R 11 , R 12 and R 13 are each independently H, alkyl or phenyl; and
n and m are each independently an integer 0–5.
29. The method of claim 27 , wherein said first olefin and said second olefin are the same.
30. The method of claim 20 , wherein said polyolefin is an atactic living polyolefin.
31. The method of claim 20 , wherein said block-polyolefin composition comprises a diblock copolymer having the formula: atactic-poly(first olefin)-b-isotactic-poly(second olefin).
32. The method of claim 31 , wherein said atactic-poly(first olefin) block has degree of polymerization about equal to said isotactic-poly(second olefin) block.
33. The method of claim 31 , wherein said diblock copolymer composition has polydispersity about 1.02–1.1.
34. The method of claim 33 , wherein said polydispersity is about 1.05.
35. The method of claim 31 , wherein said diblock copolymer is monomodal.
36. The method of claim 1 , wherein said polyolefin is an isotactic polyolefin having polydispersity index of about 1.02–1.1.
37. The method of claim 1 , wherein said contacting said metallocene pre-catalyst with said substoichiometric amount of said co-catalyst comprises forming an active metallocene catalyst; and said polymerizing by degenerative transfer comprises reacting said first monomer with said active metallocene catalyst to form a propagating polyolefin center.
38. The method of claim 37 , wherein said polymerizing by degenerative transfer further comprises reacting said propagating polyolefin center with said metallocene pre-catalyst to form a dormant polyolefin chain and an active metallocene catalyst.
39. The method of claim 38 , wherein said reacting comprises transferring a methyl group or a chloride group from said metallocene pre-catalyst to said propagating polyolefin center to form said active metallocene catalyst and said dormant polyolefin chain.
40. The method of claim 38 , wherein said polymerizing by degenerative transfer further comprises transferring a methyl group or a chloride group between said propagating polyolefin center and said dormant polyolefin chain.
41. A method of producing a polyolefin composition, comprising contacting a metallocene pre-catalyst with a co-catalyst and an olefin; and polymerizing said olefin by degenerative transfer Ziegler-Natta polymerization.
42. The method of claim 41 , wherein said polymerizing said olefin comprises exchanging a ligand between said metallocene pre-catalyst and a propagating polyolefin center.
43. The method of claim 42 , wherein said exchanging comprises forming an active Ziegler-Natta catalyst from said metallocene pre-catalyst and forming a dormant polyolefin chain from said propagating polyolefin center.
44. The method of claim 41 , wherein said polymerizing said olefin by degenerative transfer polymerization further comprises exchanging a ligand between a propagating polyolefin center and a dormant polyolefin chain.
45. The method of claims 42 or 44 , wherein said ligand is a methyl group or chloride group.
46. The method of claim 42 , wherein said exchanging said ligand between said metallocene pre-catalyst and said propagating polyolefin center is fast relative to said polymerization.
47. The method of claim 44 , wherein said exchanging said ligand between said propagating polyolefin center and a dormant polyolefin chain is fast relative to said polymerization.
48. The method of claim 47 , wherein said exchanging a ligand between said metallocene pre-catalyst and said propagating polyolefin center, and said exchanging a ligand between said propagating polyolefin center and a dormant polyolefin chain are fast relative to said polymerization and said polyolefin has polydispersity of about 1.02–1.1.
49. The method of claim 41 , wherein the number average molecular weight of said polyolefin composition is inversely linearly proportional to the initial concentration of said metallocene pre-catalyst and the polydispersity of said polyolefin composition is about 1.02–1.1.
50. The method of claim 49 , wherein the number average molecular weight of said polyolefin composition is inversely linearly proportional to the initial concentration of said metallocene pre-catalyst at constant initial monomer and initial co-catalyst concentrations.
51. The method of claim 1 , wherein said substoichiometric amount of said co-catalyst is less than 0.9 equivalents of said metallocene pre-catalyst.
52. The method of claim 1 , wherein said substoichiometric amount of said co-catalyst is in the range of about 0.1 to about 0.8 equivalents of said metallocene pre-catalyst.