Note: Descriptions are shown in the official language in which they were submitted.
WO 00/52061 PCT/GB00/00695
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USE OF AN INITIATOR FOR CONTROLLED POLYMERISATION REACTIONS
The present invention relates to use of an initiator
for controlled polymerisation reactions, in particular use
of an initiator for controlled polymerisation of vinyl
containing monomers to produce a polymer or copolymer.
Controlled polymerisation systems are of considerable
importance in macromolecular chemistry since they allow for
controlled preparation of polymers having a specific desired
morphology. For example, by controlling the_ratio of
monomer to initiator concentration the molecular weight,
molecular weight distribution, functionality, topology
and/or dimensional structure of the resulting polymer can be
controlled.
For many years free radical polymerisation has been a
commercially important process for the preparation of high
molecular weight polymers. A wide variety of monomers may
be polymerised or copolymerised by free radical
polymerisation under relatively simple conditions in bulk,
solution, emulsion, suspension or dispersion. However, a
drawback of conventional free radical polymerisation is the
lack of control of the morphology of the resulting polymer.
Processes for controlled radical polymerisation have
been proposed. For example, WO 96/30421, WO 97/18247 and WO
98/01480 disclose polymerisation processes based on atom
transfer radical polymerisation (ATRP) which provide for
controlled radical polymerisation of styrene,
(meth)acrylates, and other radically polymerisable monomers.
The processes disclosed comprise the use of (i) an
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initiating system which comprises an initiator having a
radically transferable atom or group, for example a
1-phenylethyl halide, alkyl 2-halopropionate,
p-halomethylstyrene, or a,a,'-dihaloxylene,(ii) a transition
metal compound, for example Cu ( I ) Cl , Cu ( I ) Br, Ni ( 0 ) , FeCl2,
or RuCl2, and (iii) a C-, N-, O-, S-, or P-containing ligand
which can co-ordinate with the transition metal, for example
bipyridine or (alkoxy)3P. In Chem. Commun., 1999 99-100
Haddleton et al disclose solid supported copper catalysts,
which are alleged to be easy to remove from polymer products
for reuse, and their use in atom transfer polymerisation of
methyl methacrylate using ethyl-2-bromoisobutyrate as an
initiator.
WO 98/01480 further discloses the preparation and use
of polydimethylsiloxane (PDMS) based macroinitiators; for
example, benzyl chloride end groups are introduced to PDMS
having silicon bonded hydrogen atoms by a platinum catalysed
hydrosilylation reaction with vinylbenzylchloride. However,
this route produces two isomers, a, and (3, having different
activities. The (3 isomer which represents 650 of the
product is totally inactive towards initiation of controlled
polymerisation reactions of vinyl monomers, and use of the a,
isomer results in polymers or copolymers containing
unacceptably high amounts of unreacted siloxane which is
difficult to remove due to slow initiation of the reaction.
We have prepared an alternative PDMS based
macroinitiator by a condensation reaction which is capable
of initiating a controlled polymerisation reaction of vinyl
monomer and yielding a well defined polymer or copolymer,
and which is more reactive than the aforementioned prior art
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PDMS based macroinitiator and leaves little or no unreacted
siloxane remaining in the product.
The word "comprises" where used herein is used in its
widest sense to mean and to encompass the notions of
"includes", "comprehends" and "consists of".
According to the present invention there is provided
use of an initiator for initiating controlled polymerisation
reactions, the initiator having at least one group -D-CRBZX'
and comprising units of the formulae (R'3Si01~2) , (R'2Si02~2) ,
(R'Si03~2) , and/or (Si04~2) , wherein D is a divalent straight
chain or branched alkylene group containing an oxygen or
nitrogen heteroatom and/or substituted by a carbonyl group,
each R8 is independently an alkyl group or a hydrogen atom,
X' is a halogen atom, and each R' is independently a group -
D-CRgZX' or an optionally substituted hydrocarbon group.
The initiator may be a linear, branched, cyclic or
resinous siloxane.
R' may be an alkyl group, (e. g. a methyl, ethyl, propyl
or butyl, pentyl or hexyl group), a substituted alkyl group,
(e. g. a fluoropropyl group), an alkenyl group, (e. g. a vinyl
or hexenyl group), an aryl group (e.g. a phenyl group), an
aralkyl group (e. g. a benzyl group) or an alkaryl group
(e. g. a tolyl group), and is preferably a C1-C6 alkyl group.
Preferably, at least one group R8 in each group -D-
CR82X' is an alkyl group, i.e. X' is preferably a secondary
or tertiary halogen atom, more preferably both groups R8 in
each group -D-CR82X' are alkyl groups, i.e. X' is more
preferably a tertiary halogen atom. In a particularly
preferred embodiment each RB is a methyl group.
X is preferably a bromine atom.
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Preferred examples of divalent group D include
O O
~N,R~o
OR~° ) r
R9
wherein R9 is an alkyl group, for example a methyl group, or
a hydrogen atom, each R1° is independently a straight chain
or branched alkylene group, and r is an integer of from 1 to
4.
Preferred initiators used in the present invention have
the formula R'3Si0 (SiR'20) qSiR'3 wherein R' is as defined above
and q is 0 or a positive integer, for example from 10 to
100.
Particularly preferred initiators have the general
formula (VI I I )
R' R' R'
X'R82C-D-Si-O-f -Si-O~Si-D-CR$ZX'
R' R' R'
(VIII)
wherein R', R8, D, X' and q are as defined above.
Examples of initiators of formula (VIII) are:
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O H3 i H3 ~H3 O
Br i ~ Si-O-~-~Si-O~-Si N Br
~I I I ~I
CH3 CH3 CH3 CH3 CH3
O ~H3 i H3 ~H3 O
Br N Si-O~Si-O--~-Si N Br
CH3 CH3 CH3
O H3 ~ Hs Hs O
Br O~--~O~ ~-~O t O Br
Si-O-~-Si-O~-Si
I I I
CH3 CH3 CH3
and
O i H3 i H3 ~H3 O
Br O Si-O~Si-O~SI i O Br
I I I
CH3 CH3 CH3
wherein s is 0 or a positive integer, for example from 1 to
100, and t is a positive integer, for example from 1 to 10.
The initiator used in the present invention may be made
by a method which comprises performing a condensation
reaction between (i) a siloxane having at least one group R11
and comprising units of the formulae (R113S1O1~2) , (R112S1O2~2) .
(R11S1O3~2) , and/or (S1O4~2) wherein at least one group Rll is
an amino-, hydroxy- or alkoxy- group, or an amino-, hydroxy-
or alkoxy-substituted alkyl group and the remaining groups
R11 are each independently a group R' as previously defined,
and (ii) a compound X'CRez-E wherein E is a group capable of
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participating in a condensation reaction with the amino-,
hydroxy- or alkoxy- group, or an amino-, hydroxy- or alkoxy-
substituted alkyl group to form a divalent straight chain or
branched alkylene group containing an oxygen or nitrogen
heteroatom and/or substituted by a carbonyl group, and Re
and X' are as previously defined.
The particular reagants (i) and (ii) defined above to
be used in the method of making the initiator will of course
depend upon the particular initiator to be made. For
example, to make an initiator in which divalent group D
previously defined comprises a peptide linkage, the
condensation reaction may be performed between an aminoalkyl
substituted siloxane and an acyl halide:
R11 R11
2 Br Br + H2N~Si-O--~Si-O-~-Si NH2
R11 R11 R11
-2 HBr O R11 R11 R11 O
Br IV~Si-O--~--Si-O-~--Si~N Br
R11 R11 R11 H
By way of further example, if divalent group D is to
comprise a carboxy linkage then the condensation reaction
may be performed between a hydroxyalkyl substituted siloxane
and an aryl halide:
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- 7 _
R11 R11
2 Br Br + HO S~-O~Si-O~Si OH
R11 R11
-2 HBr ~ R11 R11 R11
-' Br O Si-O--~-Si-O-~Si O Br
R11 R11
The condensation reaction may be performed at room
temperature or above, for example from 50 to 100°C.
According to the present invention the initiator is
used for initiating controlled polymerisation reactions,
especially controlled polymerisation of vinyl containing
monomers, such as those described in WO 96/30421, WO
97/18247, WO 98/01480 and Chem. Commun., 1999 99-100
(Haddleton et al). The present initiator is capable of
initiating a controlled polymerisation reaction of vinyl
monomer to yield a well defined polymer or copolymer. It is
more reactive than the aforementioned prior art PDMS based
macroinitiators and leaves little or no unreacted siloxane
remaining in the product.
We have found that the initiator is particularly
effective for controlled polymerisation of vinyl monomers
when used together with a particular catalyst composition
which is solid at room temperature and comprises a
transition metal or transition metal compound having on
average more than one ligand co-ordinated thereto, each
ligand being supported by a support via a divalent group R,
wherein R is an optionally substituted C1-CZO straight chain,
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branched, or cyclic alkylene group, arylene, alkarylene or
aralkylene group.
The transition metal may, for example, be selected from
copper, iron, ruthenium, chromium, molybdenum, tungsten,
rhodium, cobalt, rhenium, nickel, manganese, vanadium, zinc,
gold and silver. Suitable transition metal compounds
include those having the formula MY wherein M is a
transition metal ration and Y is a counter anion. M is
preferably selected from Cu (I) , Fe (II) , Co (II) , Ru (II) and
Ni (II) , and is most preferably Cu (I) . Y may be, for
example, Cl, Br, F, I, N03, PF6, BF4, 504, CN, SPh, SCN, SePh
or triflate (CF3S03) , and is most preferably C1 or Br.
The catalyst composition comprises on average greater
than one ligand co-ordinated with the transition metal or
transition metal compound, and preferably has at least two
co-ordinated ligands. Suitable ligands include C-, N-, O-,
P-, and S- containing ligands which can co-ordinate with the
transition metal or transition metal compound. WO 97/47661,
WO 96/30421, WO 97/18247 and WO 98/01480 disclose many
examples of suitable ligands. Preferred ligands are those
which contain an organodiimine group, in particular a
1,4-diaza-1,3-butadiene of formula (I),
R2
RAN
R2
(I)
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a 2,2'-bipyridine of formula (II),
2
R R2 R2
R2
~N ~N \
(II)
a pyridine-2-Carboxaldehyde imine of formula (III),
R2
(III)
an oxazolidone of formula (IV),
O O
R ~N N
(IV)
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or a quinoline carbaldehyde of formula (V),
R2
/ . \
N ~Rz
R2 N ~
(V)
wherein each R1 is independently a hydrogen atom, an
optionally substituted C1-CZO straight chain, branched, or
cyclic alkyl group, aryl, alkaryl, aralkyl group or halogen
atom. Preferably, R1 is a hydrogen atom or an unsubstituted
C1-C12 alkyl group. Each R2 is independently an R1 group, a
Cl-C2o alkoxy group, NOZ- , CN- , or a carbonyl group .
One or more adjacent Rl and Rz groups, and RZ and R2
groups, may form CS-C8 cycloalkyl, cycloalkenyl,
polycycloalkyl, polycycloalkenyl or cyclic aryl groups, for
example cyclohexyl, cyclohexenyl or norbornyl groups. The
2-pyridinecarbaldehyde imine compounds of formula (III) may
comprise fused rings on the pyridine group.
A preferred organodiimine containing group is of
formula (III) wherein each R2 is a hydrogen atom.
Divalent group R is preferably a C1-C6 unsubstituted
straight chain or branched alkylene group, for example a
propylene group, or an aralkylene or alkarylene group, for
example a benzylene or tolylene group.
The support may be an inorganic or organic network or
polymer. Suitable inorganic networks or polymers consist of
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oxides of Si, Zr, Al or Ti, including mixed oxides thereof,
for example a zeolite. A preferred inorganic support is a
siloxane polymer or network having units of the formula
(R33S1O1~2) a (R32S1O2~2) b (R3Si03~2) ~ (Si04~z) a wherein each R3 is
independently an alkyl group, preferably a methyl group, a
hydroxyl group or alkoxy group, a, b, c and d are each
independently 0 or a positive integer, and a+b+c+d is an
integer of at least 10. The siloxane polymers and networks
may be formed by polymerisation or cross-linking of silicon-
containing monomers or oligomers, for example
organofunctional silanes, silicas, and organocyclosiloxanes
having the formula (R42Si0)e wherein R4 is an alkyl group,
for example a C1-C6 alkyl group, most preferably a methyl
group.
Suitable organic network or polymer supports may
comprise any organic material which will render the catalyst
composition solid at room temperature and will not hinder
any polymerisation reaction which the catalyst composition
is to catalyse. Examples of suitable organic networks or
polymers include polyolefins, polyolefin halides,
oxides and glycols, polymethacrylates, polyarylenes and
polyesters.
The ligands may be physically or chemically attached to
the support via divalent group R; however, chemical bonding
of the ligands to the support via divalent group R is
preferred.
Particularly preferred catalyst compositions for
catalysing controlled polymerisation reactions which are
initiated according to the present invention are according
to formula (VI) and (VII),
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I ~ ~ I I
i~ ~Nw i~ ~Nw
\ ~ Cu~ \ Cu~
N I N~ ~ I N/
\ Br / / Br
siloxane polymer or network
~ organic polymer or network
(VI) (VII)
wherein the siloxane polymer or network has units of the
formula (R33S1O1~2) a (R32SZO2~2) b (R3Si03~2) ~ (Si04~2) di R3i a, b, c and
d are as defined above and n is a positive integer.
The catalyst composition may be made by conventional
methods known to those persons skilled in the art. The
molar ratios of reagents to be used to make the catalyst
composition must be such that in the catalyst composition
the transition metal or transition metal compound has on
average more than one ligand co-ordinated thereto.
By way of example, organodiimine containing groups
which are diazabutadienes may be prepared by reaction of
glyoxal with aniline derivatives:
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-N ~ ~ X
-O
+ H2N ~ ~ X ---> N
O
X
wherein X is a leaving group, for example a hydroxy or
alkoxy group or a halogen atom, which diazabutadienes may
then react with a suitable support material and transition
metal compound to form the catalyst composition, for
example:
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OH OH
X O O
+ MY +
N
organic polymer or network
X
organic polymer or network
O O
/ \
NON
~ M ~
Y
Nw ,N
wherein n is as defined above.
By way of further example, organodiimine containing
groups which are pyridine-2-carboxaldehyde imines of formula
(III) above may be made by reaction of ethanolamine with
pyridine-2-carboxaldehyde:
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OH N ~
+ / ~ N /
HZN p H N i
HO
The pyridine-2-carboxaldehyde imine may then be reacted
with a suitable support material Z and transition metal
compound to form the catalyst composition, as illustrated
above.
The catalyst composition hereinabove described in
detail has an advantage over the aforementioned prior art
controlled polymerisation methods in that the catalyst
composition is a solid at room temperature and is thus
recoverable from the polymer product and is reusable, and
allows for a high degree of control over the polymerisation
reaction. Particularly advantageous catalyst compositions
are those which are a solid at room temperature but which
have a melting point at a temperature lower than the
temperature at which the polymerisation reaction occurs.
Particularly effective polymerisation reactions may be
performed in this way when the catalyst composition is a
fluid in the reaction mixture at the reaction temperature
and thus the transition metal compound may more easily blend
into the reaction mixture to effect catalysis of the
reaction. As the temperature of the product cools after the
reaction has occurred to below the melting point of the
catalyst composition the catalyst may solidify and be
recovered from the reaction mixture.
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The vinyl containing monomer to be polymerised may be a
methacrylate, an acrylate, a styrene, methacrylonitrile or
dime. Examples of vinyl containing monomers include methyl
methacrylate, ethyl methacrylate, propyl methacrylate, butyl
methacrylate, and other alkyl methacrylates, and the
corresponding acrylates, including organofunctional
methacrylates and acrylates, including glycidyl
methacrylate, trimethoxysilyl propyl methacrylate, allyl
methacrylate, hydroxyethyl methacrylate, hydroxypropyl
methacrylate, dialkylaminoalkyl methacrylates, and
fluoroalkyl (meth)acrylates. Other suitable vinyl
containing monomers include methacrylic acid, acrylic acid,
fumaric acid and esters, itaconic acid (and esters), malefic
anhydride, styrene, a-methylstyrene, vinyl halides, for
example vinyl chloride and vinyl fluoride, acrylonitrile,
methacrylonitrile, vinylidene halides of the formula
CHZ=C(halogen)2 wherein the halogen may be C1 or F,
optionally substituted butadienes of the formula
CHZ=CRS-CRS=CHZ wherein each RS is independently H, a C1-Clo
alkyl group, C1 or F, acrylamide or derivatives thereof of
the formula CHZ=CHCONR62 and methacrylamide or derivatives
thereof of the formula CHz=C (CH3) CONR62 wherein R6 is H, a
Cl-Clo alkyl group or C1. Mixtures of different monomers may
also be used.
Polymerisation may take place under an inert
atmosphere, for example under argon or nitrogen.
The catalyst composition may be used in an amount of
from 1 to 50%, preferably from 1 to 200, more preferably
from 5 to loo by weight of the monomer.
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A variety of polymers and copolymers can be produced by
controlled polymerisation reactions initiated according to
the present invention. A large variety of monomers may be
polymerised to afford homopolymers, random or gradient
copolymers, periodic copolymers, block copolymers,
functionalised polymers, hyperbranched and branched
polymers, graft or comb polymers, and polysiloxane-organic
copolymers. Polysiloxane-organic copolymers have a number
of potential applications; for example, polysiloxane-
polyhydroxyalkyl acrylate block and graft copolymers are
used in soft contact lens applications, polysiloxane-
aminoacrylate copolymers are usable as antifoam and anti-dye
transfer agents, and polysiloxane-aminoacrylate copolymers
having a short aminoacrylate block are usable as textile
treating agents, polyalkoxysilylalkylacrylate-polysiloxane
and polyepoxyglycidylacrylate-polysiloxane copolymers are
usable as additives for epoxy resins, curable powder
coatings and sealants, long alkyl methacrylate or acrylate-
polysiloxane copolymers are usable as surface modifiers or
additives for polyolefins and polyester-polyacrylate
copolymers, and the ABA methacrylate or acrylate-
polysiloxane block copolymer may be usable as a plasma
crosslinkable oxygen barrier coating, and phosphobetaine or
sulphobetaine-polysiloxane ionomers are biocompatible, for
example for use in shampoos and other hair treating agents.
The present invention will now be illustrated by way of
example.
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Reference Example 1 - preparation of bromoisobutyrylamide
end-capped polydimeth~rlsiloxane (PDMS) macroinitiator
To a solution of 9.Og (62.9mmo1) of tetramethylazasila-
cyclopentane in 40m1 of toluene under NZ in a 250 ml flask
equipped with a magnetic stirrer, condenser and addition
funnel was added dropwise 100.Og of hydroxy terminated PDMS
(degree of polymerisation (Dp) - 45) in 40m1 toluene at room
temperature. After heating for 2 hours at 50°C volatile
materials were removed under vacuum to afford 93.Og of
colourless liquid. Analysis by 13C, Z9Si NMR and FTIR
confirmed the liquid to be amine end-capped PDMS (Dp=45).
Then, to 30g of the amine end-capped PDMS in 50m1
triethylamine in a 100m1 flask equipped with a magnetic
stirrer, condenser and addition funnel was added dropwise
under NZ 4.25g (18.5mmo1) of bromoisobutyrylbromide in 20m1
toluene at room temperature. The mixture was kept at 90°C
for 1 hour with stirring prior to filtration of salts and
evaporation of solvents under vacuum. The polymer was
washed with toluene and water. The organic phase was dried
with magnesium sulphate, filtered and volatiles removed to
afford 27.88 (86o yield) of a pale yellow liquid. 1H, 13C
and 29Si NMR characterisation of the liquid confirmed the
formation of N-bromoisobutyryl, N-methylamino, 2-methyl
2 5 propyl endblocked PDMS ( Br ( CH3 ) zCCON ( CH3 ) CHZCH ( CH3 ) CH2 ) - )
.
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Reference Example 2 - preparation of first solid supported
copper catalyst
20.Og (186.7mmol) of 2-pyridine carboxyaldehyde and
10.78 (74.6mmo1) of CuBr were mixed in 62m1 of
tetrahydrofuran in a 100m1 flask equipped with a magnetic
stirrer and a condenser. Insoluble material was dissolved
by addition of 33.58 (186.8mmo1) of 3-aminopropyltrimethoxy-
silane. The reaction was exothermic forming a deep red
solution, which was allowed to cool to room temperature
prior to the addition of 0.078 (l.9mmol) of NH4F diluted in
1.7m1 water. The solution was then heated under stirring at
60°C for 24 hours. Volatile materials were evaporated under
vacuum and the resulting solid was ground, washed with ether
and dried in vacuo at 80°C to afford 45.5g of brown-red
powder (Cu(%m/m)=8.92%, insoluble in toluene, xylene and
acetone).
Example1-polymerisation of methvlmethacrvlate
5.398 (53.9mmo1) of methylmethacrylate (MMA) in 11.5m1
of anhydrous p-xylene was added to 0.66g of the catalyst
prepared in Reference Example 2 above in a schlenk tube.
The mixture was deoxygenated by a single freeze-pump-thaw
cycle prior to addition of,l.Og of the macroinitiator
prepared in Reference Example 1 above at room temperature.
The solution was heated at 90°C for 6 hours under NZ and
samples were taken against time for 1H NMR analysis. The
final polymer and catalyst were separated by simple
filtration on paper. The polymer was dried under vacuum to
afford 3.9g of a pale yellow solid. The degree of
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conversion of the monomer observed by 1H NMR was 590. The
catalyst was washed with toluene and ether and dried in
vacuo to afford 0.518 of active copper catalyst, reusable
for further polymerisations. The results are given in Table
1 below and show a very good correlation between theoretical
and experimental molecular weight and hence controlled
polymerisation:
Table 1
Time (hours) Conversion o Mnth (g/mole) Mn (g/mole) PDMS
0 0 3710 3710 100
2 10 5710 5480 68
3 27 9110 8590 43
4 42 12160 11470 32
5 52 14130 14090 26
6 59 15450 15200 24
Mn = number average molecular weight
Mnt,, = theoretical number average molecular weight
Example 2 - polymerisation of MMA using recycled catalyst
4.018 (40.1mmo1) of MMA in 8.6m1 of anhydrous p-xylene
was added to 0.498 of copper catalyst recycled from Example
1 above in a schlenk tube. The mixture was deoxygenated by
a single freeze-pump-thaw cycle prior to addition of 0.7448
of the macroinitiator prepared in Reference Example 1 above.
The solution was heated at 90°C for 24 hours under N2 and
samples were taken against time for 1H NMR analysis. The
results are given in Table 2 below and show a good
correlation between theoretical and experimental molecular
weight and hence controlled polymerisation:
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Table 2
Time (hours) Conversion Mnth (g/mole) Mn (g/mole) PDMS
% o
0 0 3710 3710 100
4 9 5510 5350 70
6 13 6310 5990 62
24 84 20500 18700 20
Reference Example 3 - preparation ofbromoisobutvrate end-
capped PDMS macroinitiator
518 PDMS having -Si (CH3) 2- (CHZ) z-o- (CH2) 3CH20H terminal
units and a number average molecular weight of 2084 (0.049
mole of OH) and 5.438 (0.053mo1) of triethylamine were
placed into a 100m1 flask equipped with a magnetic stirrer a
condenser and an addition funnel containing 20m1 of toluene.
12.378 (0.053 mole) of bromobutyratebromide was added
dropwise at room temperature and the reaction was allowed to
react overnight at room temperature prior to filtration of
salts and evaporation of solvents. The polymer was washed
with toluene and water. The organic phase was dried with
magnesium sulphate, filtrated and volatiles removed under
reduced pressure. The 1H NMR spectrum confirms the total
disappearance of the carbinol function (8=3.56ppm) and the
appearance of -Si (CH3) 2- (CHz) 2-0- (CHz) 3CHZOCOC (CH3) ZBr at
4.19ppm.
Reference Example 4 - preparation of second solid supported
copper catalyst
100.48 (560.Ommo1) of 3-aminopropyltrimethoxysilane and
63.08 (558.2mmol) of 2-pyridine carboxyaldehyde were mixed
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in a 11 flask equipped with a magnetic stirrer and a
condenser. After stirring for 10 minutes 26.88 (186.8mmol)
of CuBr, 170.48 (1119.4mmol) tetramethoxysilane, 45.28
(2511.1mmol) water and 0.68 (16.2mmol) NH4F were
successively added to the flask. A strong exotherm was
observed affording an homogenous dark solution at room
temperature. After 48 hours the solution gelled to a soft
gel. The solids were aged for one week before removing
volatiles by evaporation under vacuum. The resulting solid
was ground, washed with ether and dried in vacuo at 80°C for
8 hours to afford 202.58 of a brown-red powder.
Example 3 - polymerisation of MMA
1908 (l.9mo1) of MMA in 300m1 of anhydrous p-xylene was
added to lOg of the catalyst prepared in Reference Example 4
above (previously extracted with p-xylene for 6 hours in a
soxhlet) in a 500m1 schlenk tube. The mixture was
deoxygenated by a single freeze-pump-thaw cycle and heated
at 90°C prior to addition of lOg of the macroinitiator
prepared in Reference Example 3 above. The reaction was
continued for 30 hours at 90°C. Samples were taken against
time for 1H NMR analysis. During polymerisation the
solution became very viscous but remained clear and the
catalyst remains visible in the polymer solution. After
polymerisation the solid catalyst was filtered out. The
degree of conversion of the monomer observed by 1H NMR was
440, and the Mn as measured by 1H NMR was 20,900. The
catalyst was extracted with p-xylene in a soxhlet for 6
hours, reusable for further polymerisations. GPC analysis
of the polymer showed a narrower molecular weight
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distribution (Mnth/Mn = 1.29) compared to the starting
polysiloxane macroinitiator (Mnt,,/Mn = 1.5).
Example 4 - polymerisation of MMA usin~ycled catalyst
30g (0.3mo1) of MMA in 30m1 of anhydrous p-xylene was
added to 2.3g of the catalyst collected from Example 3 above
(previously extracted with p-xylene for 6 hours in a
soxhlet) in a 100m1 schlenk tube. The mixture was
deoxygenated by a single freeze-pump-thaw cycle and heated
at 90°C prior to addition of 3g of the macroinitiator
prepared in Reference Example 3 above. The reaction was
continued for 44 hours at 90°C. Samples were taken against
time for 1H NMR analysis. During polymerisation the
solution becomes very viscous but remains clear and the
catalyst remains visible in the polymer solution. After
polymerisation the solid catalyst was filtered out. The
results are shown in Table 3 below and show an excellent
correlation between theoretical and experimental molecular
weight and hence controlled polymerisation.:
Table 3
Time (hours) Conversion Mnth (g/mole) Mn (g/mole) PDMS
o
0 0 2400 2400 100
28 22 7800 7800 30.7
44 33.5 10400 10400 23
Reference Example 5 - preparation of third solid supported
copper catalyst
5g (0.01 mole -NH2) of aminomethylpolystyrene and 1.2g
(0.012 mole) of pyridinecarboxyaldehyde were added to a
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100m1 flask containing 50m1 diethylether at room temperature
and allowed to react overnight under nitrogen. After the
reaction, a yellow powder was collected, washed with
dichloromethane and toluene and dried at 65°C for 2 hours.
4.5g of the powder was mixed with 1.028 of CuBr in 50m1 of
acetone and agitated until all the powder turned black. The
reaction was continued under acetone reflux for 3 hours.
After the reaction, the powder was washed with water and
extracted with methanol in a soxhlet for 7 hours. Solid
state 13C NMR confirmed the presence of imine groups and the
absence of amine groups.
Example 5 - polymerisation of MMA
20m1 of anhydrous p-xylene and lOg (l.9mole) of MMA
were added to a 100m1 schlenk tube containing 5.3g of copper
catalyst prepared according to Reference Example 5 above.
The mixture was deoxygenated by a single freeze-pump-thaw
cycle and then heated at 90°C prior to addition of l.Olg of
PDMS macroinitiator prepared in Reference Example 3 above.
The reaction was continued for 5 hours at 90°C and sampled
against time. During polymerisation the solution became
very viscous but remained clear. The catalyst particles are
visible in the polymer solution. After 5 hours of
polymerisation, 1H NMR studies measured 33o monomer
conversion and Mn=7100.
Example 6 --polymerisation of MMA
47.48 (0.47mo1) of MMA in 50m1 of anhydrous p-xylene
was added to 19.4g of copper catalyst prepared according to
Reference Example 4 above in a 250m1 schlenk tube. The
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mixture was deoxygenated by a single freeze-pump-thaw cycle
and heated at 90°C prior to addition of 5.Og of the
macroinitiator prepared according to Reference Example 3
above. The reaction was continued for 4 hours at 90°C under
N2. Samples were taken against time for H1 NMR analysis.
During polymerisation the solution becomes very viscous and
the catalyst remains visible in the polymer solution. The
results are shown in Table 4 below and show a very good
correlation between theoretical and experimental molecular
weight and hence controlled polymerisation.:
Table 4
Time (mins) Conversion Mnth (g/mole) Mn (g/mole) PDMS
o
0 0 960 960 100
32 0 960 960 100
60 21 2850 2960 32.3
123 65 6811 7760 12.6
182 84 8522 9360 10.3
237 95 9512 10760 8.9
Reference Example 6 - preparation of PDMS macroinitiator
having pendant bromoisobutyrate fps.
A 500 ml 3-neck reaction flask equipped with a dropping
funnel, a thermometer and a magnetic stirrer was charged
with 80.5 g of dimethylethoxy end-blocked
dimethylmethyl(aminopropyl)siloxane having a degree of
polymerisation of 100 and containing 0.018 mole NHZ, and 100
ml of p-xylene. After homogenisation, 3.35 ml (0.024 mole)
of triethylamine was added and 5.53 g (0.024 mole) of bromo-
isobutyryl bromide were injected slowly at room temperature.
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The reaction was allowed to proceed for 3 hours at 50°C
under agitation. After reaction, p-xylene was evaporated
prior the addition of 300 ml of n-hexane to precipitate the
triethylammonium salt. This step was followed by filtration
and evaporation of hexane. The product was a clear yellow
and very viscous polymer. The disappearance of amine
functionality was confirmed by 1H NMR spectroscopy, the peak
of CHZCHZNHZ shifts from 3.99 ppm to 3.30 ppm and a new
signal corresponding to -NH-COC(CH3)ZBr appears at 6.99 ppm.
The bromination yield =100 % although some terminal ethoxy
groups are hydrolysed.
Reference Example 7 - preparation of fourth solid supported
copper catalyst
A 2000 ml 3-neck reaction flask equipped with a
dropping funnel, a thermometer and a reflux condenser was
charged with 246 g (1.37 mole) of aminopropyltrimethoxy-
silane and 300 ml of p-xylene. Then, 75 g (4.16 mole) of
water was added over 60 minutes whilst distilling off
methanol. After methanol removal, p-xylene is stripped off
under reduced pressure to yield a white brittle solid. 84 g
of the solid and 300 ml of p-xylene were then charged into a
1000 ml reaction flask and 70 g (1.0 mole) of 2-pyridine
carboxyaldehyde was added slowly with cooling. After
addition of the 2-pyridine carboxyaldehyde, 57 g of CuBr was
added under strong agitation keeping the temperature below
30°C. The agitation was maintained until the total
disappearance of the green colour characteristic of free
Cu(I). After the reaction, the solid was separated from the
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solvent, washed with toluene and used without further
extraction. Theoretical CuBr w/w o - 29.
Example 7 - polymerisation of MMA
A 250 ml Schlenk reaction flask was charged with 2.65 g
(0.76 mole) of catalyst prepared in Reference Example 7
above and 4.85 g(1.2 mmole)of the macroinitiator prepared in
Reference Example 6 above. The contents of the flask were
vacuum dried at 80°C to remove oxygen and then covered by a
nitrogen blanket. 28 g of MMA was then added under
nitrogen. The mixture was deoxygenated by three freeze-thaw
pump cycles in liquid nitrogen. The flask was then rapidly
heated in an oil bath to the reaction temperature of 90°C.
During the polymerisation reaction the viscosity increases
and the solid particles of the catalyst remain in the
polymer solution as a suspension. After polymerisation, the
polymer solution is filtered, the residual monomer
evaporated and the polymer analysed by 1H NMR and/or by SEC
to determine the average number molecular weight and the
polydispersity. Based on a 1000 monomer conversion and a
total macroinitiator conversion, the theoretical degree of
polymerisation is 233. From 1H NMR calculation, the
experimental degree of polymerisation is 113 after 4 hours.
Reference Example 8 - preparation of bromoisobutyrvlamide
functional MT resin macroinitiator
To a solution of 100.Og (1.45 mol) of MeSi03~2 resin
containing 3.6 wt% of OH functionality in 200 ml of toluene
under NZ in a 500 ml flask equipped with a magnetic stirrer,
condenser and addition funnel, was added dropwise 32.28
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(225.2 mmol, in excess) of tetramethylazasilacyclopentane in
50 ml toluene at room temperature. After heating for 1 hour
at 60°C volatile materials were removed under vacuum to
afford 114.08 of colourless liquid. Analysis by 13C, 29Si
NMR and FTIR confirmed the liquid to be an amine functional
MT resin containing 4.75 wto of -NMeH functionality.
Then, to 112.78 of the amine functional MT resin in
200m1 triethylamine in a 500m1 flask equipped with a
magnetic stirrer, condenser and addition funnel was added
dropwise under NZ 50.08 (217.5 mmol, in excess) of
bromoisobutyrylbromide in 150m1 toluene at room temperature.
The mixture was kept at 60°C for 2 hours with stirring prior
to filtration of salts and evaporation of solvents under
vacuum. The functionalised MT resin was washed with toluene
and water. The organic phase was dried with magnesium
sulphate, filtered and volatiles were removed to afford
108.28 of a yellow viscous liquid. 1H, 13C and 2951 NMR
characterisation of the liquid confirmed the formation of N-
bromoisobutyryl, N-methylamino, 2-methylpropyl functional MT
resin (Br (CH3) zCCON (CH3) CHZCH (CH3) CHZ) -) containing 9 . 89 wt o
of Br.
Reference Example 9 - preparation of fifth solid supported
copper catalyst
A 500 ml 3-neck reaction flask equipped with a dropping
funnel, a thermometer and a reflux condenser was charged
with 508 (279.3 mmole) of aminopropyltrimethoxy silane and
200 ml of p-xylene. 188 (1.25 moles) of water was added
over a period of 60 minutes whilst distilling off methanol.
After methanol removal, p-xylene was removed under reduced
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pressure to yield a white solid. 200m1 of toluene was then
added to the solid, and the flask equipped with Dean & Stark
apparatus. Water was azeotropically distilled from the
reaction by heating at 120°C for 4 hours. Toluene was
removed under reduced pressure to yield a white brittle
solid, which was extracted for 4 hours with p-xylene in a
Soxhlet extractor, followed by drying in a vacuum oven for 4
hours at 12 0°C .
lOg of the white solid and 50 ml of p-xylene were
charged into a 250m1 reaction flask and 8.6g (69.9 mmole) of
2-pyridine carboxyaldehyde was added slowly and left
overnight to react. An orange solid was recovered by
filtration and washed with p-xylene.
8.6g of the orange solid, 3.5g CuBr (24.5 mmole), and
30m1 of p-xylene were added to a 100m1 flask and heated at
80°C for 4 hours. After cooling, the solvent was
colourless, and absent of green colour characteristic of
free CuBr. The reaction product was filtered to obtain a
black solid which was extracted for 4 hours with p-xylene in
a Soxhlet extractor and dried in a vacuum oven at 50°C for 6
hours. (Theoretical CuBr% (w/w)= 35).
Example 8 - polymerisation of MMA
2.7g (1.17 mmole) of macroinitiator prepared in
Reference Example 8 and 3.55g of catalyst prepared in
Reference Example 9 were weighed into a Schlenk vessel and
deoxygenated by exposure to a vacuum for 30 minutes. 23.6g
(0.236 mole) of distilled methymethacrylate was added under
nitrogen and degassed by three freeze-pump-thaw cycles. The
solution was heated at 90°C for 195 minutes and samples
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removed. During polymerisation the solution became highly
viscous, which prevented the removal of samples. After 195
minutes of polymerisation, 77o monomer conversion was
measured by 1H NMR.
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