Supported polymerisation catalyst

Details Supported polymerisation catalyst Supported polymerisation catalyst

2000-08-14

2003-12-16

Wu, David W. (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S126000, C526S130000, C526S145000, C526S146000, C526S147000, C526S171000, C526S172000, C526S904000, C526S161000, C526S169100, C502S158000, C502S159000, C502S162000, C502S165000, C502S166000, C502S167000, C502S155000, C502S152000, C502S229000

Reexamination Certificate

active

06664350

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to immobilised supported polymerisation catalysts for atom transfer polymerisation of olefinically unsaturated monomers in which molecular weight control is achieved by the presence of certain transition metal, especially copper, complexes.
2. Description of Related Art
It is desirable to be able to produce high molecular weight polymers with a low molecular weight distribution by catalysed addition polymerisation, in particular of vinylic monomers. Hitherto this has been achieved by polymerising via ionic processes typically in the presence of organometallics such as alkyl lithiums which are sensitive as regards reaction with water and other protic species. As such, monomers containing functional groups are not readily polymerised. The use of ionic systems also precludes the use of solvents which contain protic groups and/or impurities resulting in very stringent reaction conditions and reagent purity being employed.
More recently atom transfer polymerisation based on the combination of a transition metal halide and alkyl halide have been utilised. For example, Matyjasewski (Macromolecules (1995), vol. 28, pages 7901-7910 and WO96/30421) has described the use of CuX (where X=Cl, Br) in conjunction with bipyridine and an alkyl halide to give polymers of narrow molecular weight distribution and controlled molecular weight. This system suffers from the disadvantage that the copper catalyst is partially soluble in the system and thus a mixture of homogeneous and heterogeneous polymerisation ensues. The level of catalyst which is active in solution is thus difficult to determine. The catalyst residues which are soluble in the reaction medium prove difficult to remove from the product. Percec (Macromolecules, (1995), vol. 28, page 1995) has extended Matyjasewski's work by utilising arenesulphonyl chlorides to replace alkyl chlorides, again this results in a mixture of homogeneous and heterogeneous polymerisation and catalyst residues are difficult to remove from the product. Sawamoto (Macromolecules, (1995), vol. 28, page 1721 and Macromolecules, (1997), vol. 30, page 2244) has also utilised a ruthenium based system for similar polymerisation of methacrylates. This system requires activation of monomer by an aluminum alkyl in order to achieve the best results, itself sensitive to reaction with protic species which is an inherent disadvantage. These systems have been described as proceeding via a free radical mechanism which suffers from the problem that the rate of termination is >0 due to normal radical-radical combination and disproportionation reactions.
The inventors have found that the use of diimines such as 1,4-diaza-1,3-butadienes and 2-pyridinecarbaldehyde imines may be used in place of bipyridines. These ligands offer the advantage of homogeneous polymerisation and thus the level of active catalyst can be accurately controlled and only one polymerisation process ensues. This class of ligand also enables the control of the relative stability of the transition metal valencies, for example, Cu(I) and Cu(II), by altering ancillary substituents and thus gives control over the nature of the products through control over the appropriate chemical equilibrium. Such a system is tolerant to trace impurities, trace levels of O
2
and functional monomers, and may even be conducted in aqueous media. This system is the subject of copending patent application number PCT/GB97/01587.
A further advantage of this system is that the presence of free-radical inhibitors traditionally used to inhibit polymerisation of commercial monomers in storage, such as 2,6-di-tert-butyl-4-methylphenol (topanol), increases the rate of reaction of the invention. This means that lengthy purification of commercial monomers to remove such radical inhibitors is not required. Furthermore, this indicates that the system is not a free-radical process. This is contrary to Matajaszewski and Sawamoto who show free-radical based systems.
A difficulty identified by the inventors for the commercialisation of the radical polymerisation system of Matajazewski and Sawamoto, and the diimine-based system described above is that high levels of catalysts are required for acceptable rates of polymerisation. This means that catalyst is relatively expensive as it is not recycled/reused and it must be removed by lengthy procedures to prevent contamination of the final product and to keep production costs down.
SUMMARY OF THE INVENTION
The inventors have therefore identified a process for attaching the catalyst to supports which allows the catalyst to be easily recovered and produces products with substantially less contamination than previously described systems.
Such supported catalysts were expected by the inventors to clump together since each metal ion can coordinate with two-ligands, each of which is attached to a support. This would reduce the effectiveness of such supported systems. However, this has not been observed by the inventors. Furthermore, the metal ion is tightly bound to the ligands and does not leach off into the surrounding solution or product, allowing it to be reused.
A first aspect of the invention provides a supported ligand for use in catalysts for polymerisation of olefinically unsaturated monomers, especially vinylic monomers, said ligand being one or more compounds attached to a support.
Such a ligand has general formula:
S(D)
n
  FORMULA 1
where:
S is the support,
D is a compound attached to the support, said compound being capable of complexing with a transition metal, and
n is an integer of one or more.
Preferably, the support is inorganic, such as silica, especially silica gel. Alternatively the support may be organic, especially an organic polymer, especially a cross-linked organic polymer, such as poly(styrene-w-divinylbenzone). Preferably the support is in the form of beads. This latter form is particularly advantageous because it has a high surface area which allows the attachment of a large number of compounds, whilst presenting a large surface area to the medium to be catalysed.
The compound (D) may be adsorbed onto the support or covalently attached to the support.
Preferably the compound is an organic compound comprising Schiff base, amine, hydroxyl, phosphine or diimine capable of complexing with a transition metal ion. Each Schiff base, amine, hydroxyl, phosphine or diimine is preferably separated from the support by a branched or straight alkyl chain, especially a chain containing 1 to 20 carbon atoms. The chain may comprise one or more aromatic groups as part of the alkyl chain.
One preferred ligand is the use of a support attached to two or more alkyl-amines, such as aminopropyl-, aminobutyl-, aminopentyl-, aminohexyl-, aminoheptyl- or aminooctyl-functionalised support. The amine groups are capable of forming a complex with one or more transition metal ions.
Especially preferred compounds are diimines.
Preferably one of the nitrogens of the diimine is not part of an aromatic ring.
Preferably the diimine is a 1,4-diaza-1,3-butadiene
where R
1
, R
2
, R
10
, R
11
, R
12
and R
13
may be varied independently and R
1
, R
2
, R
10
, R
11
, R
12
and R
13
may be H, straight chain, branched chain or cyclic saturated alkyl, hydroxyalkyl, carboxyalkyl, aryl (such as phenyl or phenyl substituted where substitution is as described for R
4
to R
9
), CH
2
Ar (where Ar=aryl or substituted aryl) or a halogen. Preferably R
1
, R
2
, R
10
, R
11
, R
12
and R
13
may be a C
1
to C
20
alkyl, hydroxyalkyl or carboxyalkyl, in particular C
1
to C
4
alkyl, especially methyl or ethyl, n-propylisopropyl, n-butyl, sec-butyl, tent-butyl, cyclohexyl, 2-ethylhexyl, octyl, decyl or lauryl. R
1
, R
2
, R
10
, R
11
, R
12
and R
13
may especially be methyl.
R
3
to R
9
may independently be selected from the group described for R
1
, R
2
, R
10
, R
11
, R
12
and R
13
or additionally OC
n
H
2n+1
, (where n is an integer from 1 to 20), NO
2
, CN or O═CR (where R=alkyl, benzyl PhCH
2

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