Polymerization catalyst and process

Details Polymerization catalyst and process Polymerization catalyst and process

1999-02-01

2001-10-30

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...

C526S172000, C502S104000, C502S162000, C556S032000, C556S110000, C556S138000

Reexamination Certificate

active

06310149

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a process for the atom transfer polymerization of olefinically unsaturated monomers in which molecular weight control is achieved by the presence of certain transition metals, especially copper, and diimine 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 catalyzed addition polymerization, in particular of vinylic monomers. Hitherto, this has been achieved by polymerizing via ionic processes typically in the presence of organometallics such as alkyl lithiums that are sensitive when reacted with water and other protic species. Therefore, monomers containing functional groups are not readily polymerized. The use of ionic systems also precludes the use of solvents that contain protic groups and/or impurities resulting in very stringent reaction conditions and reagent purity being employed.
More recently, radical polymerization systems based on the combination of a transition metal halide and an alkyl halide have been used. For example, Matyjasewski (Macromolecules (1995), vol. 28, pages 7901-7910 and W096/30421) describes 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 only partially soluble in the system and thus a heterogeneous polymerization ensues. The level of catalyst that is active in solution is thus difficult to determine. Percec (Macromolecules, (1995), vol. 28, page 1995) has extended Matyjasewski's work by using arenesulphonyl chlorides to replace alkyl chlorides, again this results in heterogeneous polymerization. Sawamoto (Macromolecules, (1995), vol. 28, page 1721 and Macromolecules, (1997), vol. 30, page 2244) has also used a ruthenium based system for similar polymerization of methacrylates. This system requires activation of monomer by aluminum alkyl, itself sensitive to reaction with protic species which is an inherent disadvantage. These systems have been described as proceeding via a free radical mechanism that suffers from the problem that the rate of termination is >0 due to normal radical-radical combination and disproportionation.
SUMMARY OF THE INVENTION
Surprisingly, the inventors of the present invention 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 polymerization and thus the level of active catalyst can be accurately controlled. 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.
A further advantage of the system of the present invention is that the presence of free-radical inhibitors traditionally used to inhibit polymerization of commercial monomers in storage, such as 2, 6-di-tert-butyl-4-methylphenol (topanol), increases the rate of reaction of the present invention. This means that lengthy purification of commercial monomers to remove such radical inhibitors is not required. Furthermore, this indicates that the system of the invention is not a free-radical process. This is contrary to the Matajaszewski and Sawamoto who show free-radical based systems.
Accordingly a first aspect of the invention provides a catalyst for addition polymerization of olefinically unsaturated monomers, especially vinylic monomers, comprising:
a) a first compound of formula 1
MY
 where M is a transition metal in a low valency state or a transition metal in a low valency state coordinated to at least one coordinating non-charged ligand and Y is a monovalent or polyvalent counterion;
b) an initiator compound comprising a homolytically cleavable bond with a halogen atom.
A “homolytically cleavable bond” means a bond that breaks without integral charge formation on either atom by homolytic fission Conventionally, this produces a radical on the compound and a halogen atom radical. For example:
However, the increase in the rate of reaction observed by the inventors with free-radical inhibitors indicates that true free-radicals do not appear to be formed using the catalysts of the present invention. It is believed that this occurs in a concerted fashion whereby the monomer is inserted into the bond without formation of a discrete free radical species in the system. That is, during propagation this results in the formation of a new carbon-carbon bond and a new carbon-halogen bond without free-radical formation. The mechanism involves bridging halogen atoms such as:
where:
 ML is a transition metal-diimine complex as defined below. A “free-radical” is defined as an atom or group of atoms having an unpaired valence electron and which is a separate entity without other interactions.
c) an organodiimine, where one of the nitrogens of the diimine is not part of an aromatic ring.
Transitional metals may have different valencies, for example Fe(II) and Fe(III), Cu(I) and Cu(II), a low valency state is the lower of the commonly occurring valencies, i.e. Fe(II) or Cu(I). Hence M in Formula I is preferably Cu(I), Fe(II), Co(II), Ru(II) or Ni(II), most preferably Cu(I). Preferably, the coordinating ligand is (CH
3
CN)
4
. Y may be chosen from Cl, Br, F, I, NO
3
, PF
6
, BF
4
, SO
4
, CN, SPh, SCN, SePh or triflate (CF
3
SO
3
). Copper (I) triflate may be in the form of a commercially available benzene complex (CF
3
SO
3
Cu)
2
C
6
H
6
. The most preferred compound is CuBr. Preferably, the second component (b) is selected from
where R is independently selectable and is selected from straight, branched or cyclic alkyl, hydrogen, substituted alkyl, hydroxyalkyl, carboxyalkyl or substituted benzyl. Preferably the or each alkyl, hydroxyalkyl or carboxyalkyl contains 1 to 20, especially 1 to 5 carbon atoms.
X is a halide, especially I, Br, F or Cl.
The second component (b) may especially be selected from Formulae 13 to 23:
where:
X=Br, I or Cl, preferably Br
R′=—H,
—(CH
2
)
p
R″ (where m is a whole number, preferably p=1 to 20, more preferably 1 to 10, most preferably 1 to 5, R″=H, OH, COOH, halide, NH
2
, SO
3
, COX—where x is Br, I or C) or:
R
111
=—COOH, —COX (where X is Br, I, F or Cl), —OH, —NH
2
or —SO
3
H, especially 2-hydroxyethyl-2′-methyl-2′bromopropionate.
Especially preferred examples of Formula 16 are:
Br may be used instead at Cl in Formulae 16A and 16B.
The careful selection of functional alkyl halides allows the production of terminally functionalized polymers. For example, the selection of a hydroxy containing alkyl bromide allows the production of &agr;-hydroxy terminal polymers. This can be achieved without the need of protecting group chemistry.
Component (c) may be a 1,4-diaza-1,3-butadiene
a 2-pyridinecarbaldehyde imine
An Oxazolidone
or a Quinoline Carbaldehyde
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, tert 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 ind

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