Note: Descriptions are shown in the official language in which they were submitted.
7 ~
- 1 - 63293-~678
MODIFIED BLOCK COPOLYMER PROCESS
This inven-tion relates to novel selectively hydrogenated
functionalized block copolymers. More particularly, i-t relates to
a process or the production of modified thermoplastic polymers
with excellent appearance properties and mechanical properties
particularly useful in blending with o-ther polymers obtained by
modifying a block copolymer composed of a conjugated diene
compound and an aromatic vinyl compound with a functional group.
This application is related to Canadian patent applica-
tion Serial Number 513,448 which has been filed on July 10, 1986.
It is known that a block copoly.~er can be obtained by an anionic
copolymerization of a conjugated diene compound and an aromatic
vinyl compound by using an organic alkali metal initiator. These
types of block copolymers are diversified in characteristics,
depending on the content of the aromatic vinyl compound.
When the content of the aromatic vinyl compound issmall, the produced block copolymer is a so-called thermoplastic
rubber. It is a very useful polymer which shows rubber elasticity
in the unvulcani~ed state and is applicable for various uses such
as mouldings of shoe sole, etc.; impact modifier for polystyrene
resins; adhesive; binder; etc.
The block copolymers with a high aromatic vinyl compound
content, such as more than 70~ by weight , provide a resin
possessing both excellent impact resistance and transparency, and
such a resin is widely used in the field of packaging. Many
proposals have been made on processes for the preparation of these
types of block copolymers (V.S. 3,639,517)~
73
The elastomeric properties of certain aromatic vlnyl polymers
also appear to be due in part to their degree of branching. While
the aromatic vinyl polymers have a basic straight carbon chain
backbone, those with elastomeric properties always have pendent
alkyl radicals. For example, EPR (ethylene-propylene rubber) has a
structure of pendent methyl radicals which appear to provide
elas~icity and other elastomeric properties. When an essentially
unbranched straight chain polymer is formed, such as some psly-
ethylenes, the resulting polymer is essentially non-elastomeric or
in other words relatively rigid, and behaves like a typical
thermoplastic without yield, low set or other properties charac-
teristic of desirable elastomers.
Block copolymers have been produced, see U.S. Patent Xe
279145 which comprlse primarily those having a general structure
A--B--A
wherein the two terminal polymer blocks A comprise thermoplastic
polymer blocks of vinylarenes such as polystyrene, while block B
is a polymer block of a selectively hydrogenated conjugated diene.
The proportion of the thermoplastic terminal blocks to the centre
elastomeric polymer block and the relative molecular weights of
each of these blocks is balanced to obtain a rubber having an
optimum combination of properties such that it behaves as a
vulcanized rubber without requlring the actual step of vulca-
nization. Moreover, these block copolymers can be deslgned not
only with this important advantage but also so as to be handled in
thermoplastic forming equipment and are soluble in a variety of
relatively low cost solvents.
While these block copolymers have a number of outs~anding
technical advantages, one of their principal limitations lies in
their sensitivity to oxidation. Thls was due to their unsaturated
character which can be minimized by hydrogenating the copolymer,
especially ln the centre section comprising the polymeric diene
block. Hydrogenation ~ay be effected selectively as disclosed in
U.S. Patent Re 27,145. These polymers are hydrogenated block
-- 3 --
copolymers having a configuration, prior to hydrogenation, of
A-B-A wherein each of the A's is an alkenyl-substituted aromatic
hydrocarbon polymer block and B is a butadiene polymer block
wherein 35-55 mol per cent of the condensed butadiene units ln the
butadiene polymer block have 1,2 configuration.
Due to their hydrocarbon nature, these selectively hydrogenated
ABA block copolymers are deficient in many applications in which
adhes4on to a polar surface ls required. E~amples include the
toughening and compatibilization of polar polymers such as the
engineerln~ thermoplastics, the adhesion to high energy substrates
by hydrogenated block copolymer elastomer based adhesives,
sealants and coatings, and the use of hydrogenated elastomer in
reinforced polymer systems. However, the placement onto the block
copolymer of functional groups which can provide interactions not
possible with hydrocarbon polymers solves the adhesion problem and
extends the range of applicability of this material.
Beyond th very dramatic improvement in interface adhesion in
polymer blends, a functionalized styrene ethylene/butylene-styrene
(S-EB-S) component can also contribute substantially to the
external adhesion characteristics often needed in polymer systems.
These include adhesion to fibres and fillers which reinforce the
polymer system; adhesion to substrates in adhesives, sealants, and
coatings based on functionalized S-EB-S polymers, adhesion of
decorations such as printing inks, paints, primers, and metals of
systems based on S-EB-S polymers; participation in chemical
reactions such as binding proteins as heparin for blood compati-
bility; surfactants in polar-nonpolar aqueous or non-aqueous
dispersions.
Functionalized S-EB-S polymer can be described as basically
3~ commerc~ally produced S-EB-S poly~ers which are produced by
hydrogenatlon of S-B-S polymer to which is chemically attached to
either the styrene or the ethylene-butylene block, chemically
functional moieties.
~;i~Ei;6D~L'73
Many attempts have been made or the purpose of improving
adhesiveness, green strength and other properties by functiona-
lizing block copolymers, and various methods have been proposed
for functionalizing synthetic conjugated diene rubbers.
Saito et al in U.S. 4,292,414 and U.S. 4J308~353 describe a
monovinyl aryl/conjugated diene block copolymer with low 1,2
content grafted with a maleic acld compound. However, the process
is limited to reaction conditions wherein the generation of free
radicals is substantially inhibited by using free radical inhibitors
or conventional stabilizers for example phenol type phosphorous
type or amine type stabilizers. The processes are limited to
thermal additlon reactions or the so-called 'tENE" reaction. This
reaction scheme depends on unsaturation ln the base polymer for
reaction sites. A reasonable amount of residual unsaturation must
be present in order to obtain an advantageous degree of function-
ality or grating onto the base polymer. A substantially
completely hydrogenated base polymer would not react appreciably
in the Saito et al process.
Hergenrother et al in U.S. 4,427,828 describe a similar
modified block copolymer with high 1,2 content ho~ever, again
produced by the 'ENE' reaction.
Tbe 'EME' process as described in the prior art results in a
modified polymer product which i6 substi~uted at a position on the
polymer backbone which is allylic to the double bond. The reaction
can be shown for maleic anhydride as ollows:
a) to main chain unsaturation
H H 3h H H H H H
- C - C = C~C- C ~ C - C = C- Allylic position
H ~ H
' ~0/ \0/
:
~'
7~31
_ 5 63293-2678
b) to vinyl unsaturation
H ~H H
-C~ C -C~) Allylic position
H ¦ ¦ H ¦~
C-H \ C-H
pl -
+ ~ ~-C~
O=C C=O O=C C=O
~O / 0/
wherein a) represents addition across a double bond in the main
chain of the base polymer and b) represents addition across a
double bond occurring in a side chain. After addition and iso-
merization the substitution is positioned on a carbon allylic to
the double bond.
The allylically substituted polymers are prone to thermal
degradation due to their thermal instability. It is known in the
art that allylic substituents can undergo what has been referred
to as a retro ENE reaction, see B.C. Trivedi9 B.M. Culbertson,
Maleic Anhydride, (Plenum Press, New York, 1982) pp. 172-173.
Further, because the ENE reaction requires a reasonable
amount of unsaturation in the precursor base polymer, as discussed
previously, the resulting functionalized copolymer product will
have a significant amount of residual unsaturation and will be
inherently unstable to oxidation.
According to the present invention, there is provided a
process for the produceion of a thermally stable, modified,
selectively hydrogenated, high 1,2 content block copolymer to
which a functional group has been grafted primarily in the vinyl-
arene block.
More preferably there is provided a process for producing
graft copolymers comprisingn~tallatinghydrogenated block copo-
lymers of conjugated dienes and monovinyl-substituted aromatic
compounds with an alkyllithium compound, and a polar compound
l ~ . ' '
~26~31173
- 6 - 63293-2678
selected from the group consisting of tertiary amines and low
molecular weight hydrocarbon ethers, to form a backbone polymer
having active lithium atoms along the polymer chain, and therea~ter
reacting said backbone polymer and at least one electrophile or graft-
able m~lecule hav.ing electrophillc functional gr~ups to forn backkone
polymers with grafted molecules attached wherein substantially all
of said graftable molecules which have been grafted are grafted to
the block copolymer in the vinylarene block.
The feature of this invention lies not only in providing a
process for the industrial production of modified blo~k copolymers
but also providing the modified block copolymers which are thermally
stable; have a low residual unsaturation, are excellent in
appearance characteristics, melt-flow characteristics, and
mechanical properties such as tensile strength and impact
resistance; etc.
The modified block copolymers produced according to the process of
the present invention are substituted in the vinylarene block as
shown in the exemplary reactions given below:
H RLi Amine ~ C02 H
--(CH2-C)n - (CH -C ~ para
... 'bl ~
~:02Li
H
(CH2 I~~n meta
: in which: RLi = Alkyl-Lithium
C2Li
-tCH2 C ~ benzylic
b` (minor product)
The structure of the substituted block copolymer specifically
determined by the location of the functionality on the polymer
~2~a~ 7~
- 7 - 63293~2678
backbone in the vinylarene block gives the block copolymer a
substantially greater degree of thermal stability.
Selectively Hydrogenated Block Copoly~er Base Polymer
Block copolymers of conjugated dienes and vinyl aromatic
hydrocarbons which may be utilized include any of those which
exhibit elastomeric properties and those which have l,2-micro-
structure contents prior to hydrogenation suitably in the range of
~rom about 7% to about 100% and preferably of from 35% to 50%.
Such block copolymers may be multiblock copolymers of varying
structures containing various ratios of conjugated dienes to vinyl
aromatic hydrocarbons including those containing up to 60 per cent
by weight of vinyl-aromatic hydrocarbon. Thus, multiblock copolymers
may be utilized which are linear or radial symmetric or asymmetric
and which have structures represented by the formulae A-B, A-B-A,
A-B-~-B, B-A. B-A-B, B-A-B-A, (AB)o 1 2 BA and the like wherein
A is a polymer biock of a vinyl aromatic hydrocarbon or a conjugated
diene/vinyl aromatic hydrocarbon tapered copolymer block and B is
a polymer block of a conjugated diene.
Block A preferably has an average molecular weight in the
range of from 500 to 60,000 and block B preferably has an average
molecular weight in the range of from 35,000 to 150,000.
The block copolymers may be produced by any well known block
polymerization or copolymerization procedures including the well
known sequential addition of monomer techniques, incremental
addition of monomer technique or coupling technique as illustrated
in, for example, UOS. Patent Nos. 3,251,905; 3,390,207; 3,598,887
and 4,219,627. As is well known in the block copolymer art,
tapered copolymer blocks can be incorporated in the multiblock
copolymer by copolymerizing a mixture of conjugated diene and
vinyl aromatic hydrocarbon monomers utilizing the difference in
their copolymerization reactivity rates. Various-patents describe
the prepara~ion of multiblock copolymers containing tapered
copolymer blocks including U.S. Patent Nos. 3,251,905; 3,265,765;
3,639,521 and 4,208,356
~2~
~ 8 - 63293-2678
Conjugated dienes which may be utilized to prepare the
polymers and copolymers are those having from 4 to 8 carbon atoms
per molecule and include 1,3-butadiene, 2-methyl-1,3-butadiene
(isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-
hexadiene, and the like. Mixtures of such conjugated dienes may
also be used. The preferred conjugated diene is 1,3-butadiene.
The polymer blocks A are prior to hydrogenation preferably polymer
blocks of a monoalkenyl-aromatic hydrocarbon,more pre~erably of a
vinyl-aromatic hydrocarbon.
Vinyl aromatic hydrocarbons which may be utilized to
prepare copolymers include styrene, o-methylstyrene,
p-methylstyrene, p-tert-butylstyrene, 1,3-dimethylstyrene,
alpha-methylstyrene, vinylnaphthalene,vinylanthracene and the
like. The preferred vinyl aromatic hydrocarbon is styrene. The
block copolymer is preferably a styrene-ethylene/butylene styrene
block copolymer.
It should be observed that the above-described polymers
and copolymers may, if desired, be readily prepared by the methods
set forth hereinbefore.However, since many of these polymers and
copolymers are commercially available, it is usually preferred to
employ the commercially available polymer as this serves to reduce
the number of processing steps involved in the overall process.
The hydrogenation of these polymers and copolymers may be carried
out by a variety of well established processes including hydro-
genation in the presence of such catalysts as Raney
B'~.
- 8a - 63293-2678
~ickel,noble metals such as platinum, palladium and the like and
soluble transition metal catalys-ts. Suitable hydrogenation
processes which can be used are ones wherein the diene-containing
polymer or copolymer is dissolved is an inert hydrocarbon diluent
such as cyclohexane and hydrogenated by reaction with hydrogen in
the presence of a soluble hydrogenation catalyst. Such processes
are disclosed in U.S. Patent Nos. 3,113,986 and 4,226,952. The
polymers and copolymers are hydrogenated in such a manner as to
produce hydrogenated polymers and copolymers having a residual
unsaturation content in the polydiene block of from 0.5 to 20
`^`` ~6~ 3
and more preferably from 0.5 to 10 per cent of their orlginal
unsaturation content prior to hydrogenation. Most preferably the
unsaturation of block B has been reduced to a value of less than 5
per cent of its original value.
In general, any materials having the ability to react with
the lithiated base polymer, are operable for the purposes of this
invention.
In order to incorporate functional groups into the base
polymer9 reactants capable of reacting with the lithiated base
polymer are necessary. These reactants may be polymerizable or
nonpolymeriæable, however, preferred reactants are nonpolymerizable
or slowly polymerizing.
The graft reaction involves nucleophilic attack of a polymer
bound lithium alkyl on an electrophile.
The class of preferred electrophiles which will form graft
polymers within the scope of the present invention include
reactants from the following groups: carbon dioxide, ethylene
oxide, aldehydes, ketones, carboxylic acid salts, their esters and
halides, epoxides, sulphur, boron alkoxides, isocyanates and
various silicon compounds.
These electrophiles may contain appended functional groups as
in the case of N,N-dimethyl-p-aminobenzaldehyde where the amine is
an appended functional group and the aldehyde is the reactive
electrophile. Alternati~ely, the electrophile may react to become
the functional site itself; as an example, carbon dioxide ~electro-
phile) reacts with the metalated polymer to form a carboxylate
functional group. By these routes, polymers could be prepared
containing grafted sites sele&ted from one or more of the following
groups of functionality type carboxylic acids, their salts and
esters, ketones, alcohols and alkoxides, amines, amides, thiols,
borates, and functional groups containing a silicon atom.
These ~unctionalities can be subsequently reacted with other
; modifying materials to produce new functional groups. For example,
7:31
-- 10 --
the grafted c~rboxylic acid described hereinbefore could be
suitably modified by esterifying the resulting acid groups in the
graft by appropriate reaction with hydroxy-containing compounds of
varying carbon atoms lengths. In some cases, the reaction could
take place simultaneously with the grafting process but in most
examples it would be practised in subsequent post modification
reaction.
The grafted polymer will usually contain in the range from
0.02 to 20, preferably 0.1 to 1b, and most preferably 0.2 to 5
~eight per cent of grafted portion.
The block copolymers, as modified, can still be used for any
purpose for which an unmodified material (base polymer) was
formerly used. That is, they can be used for adhesives and sealants,
or compounded and extruded and moulded in any convenient manner.
An example of a method to incorporate functional groups into
the base polymer primarily in the vinylarene block is metalation.
Metalation is conveniently carried out by means of a complex
formed by the combination of a lithium component which can be
represented by R'(Li) with a polar metalation promoter. The polar
compound and the lithium component can be added separately or can
be premixed or pre-reacted to form an adduct prior to addition to
the solution of the hydrogenated copolymer. In the compounds
represented by R'(Li) , the R' is usually a saturated hydrocarbon
radical of any length whatsoever, but ordinarily containing up to
20 carbon atoms, and can be a saturated cyclic hydrocarbon radical
of e.g. 5 to 7 carbon atoms. In the formula, R'(~i) x is an
integer of 1 to 3. Representative species include, for example:
methyllithium, isopropyll~thium, sec-butyllithium, n-butyllithium,
t-butyllithium, n-dodecyllithium, 1,4-dilithiobutane, 1,3,5,-tri-
lithiopentane, and the like. The lithium alkyls must be more basic
than the product metalated alkyl. Of course, other alkali metal or
alkaline earth metal alXyls could be used but the
~6~ 73
lithium alkyls are preferred due to their ready commercial availa-
bility. In a similar way, metal hydrides could be employed as the
metalation reagent but the hydrides have only limited solubility
in the appropriate solvents. The metal alkyls are preferred for
their greater solubility which makes them easier to process.
Lit~ium compounds alone usually metalate copolymers containing
aromatic and olefinic functional groups with considerable difficulty
and under high temperatures ~hich may tend to degrade the copolymer.
~owever, in the presence of tertiary diamines and bridgehead
monoamines~ metalation proceeds rapidly and smoothly. Some lithium
compounds can be used alone effectively, notably the methyllithium
types.
It has been shown that the metalation occurs at a carbon to
which an aromatic group is attached, or on an aromatic group, or
in more than one of these positions. In any event, it has been
shown that a very large number of lithium atoms are positioned
variously along the polymer chain, attached to internal carbon
atoms away from the polymer terminal carbon atoms, either along
the backbone of the polymer or on groups pendant therefrom, or
both, in a manner depending upon the distribution of reactive or
lithiatable positions. This distinguishes the lithiated copolymer
from simple terminally reactive polymers prepared by usin~ a
lithium or even a polylithium initiator in polymerizat~on thus
limiting the number and the location of the positions avallable
for subsequent attachment. With the metalation procedure described
herein, the extent of the lithiation will depend upon the amount
of metalating agent used and/or the groups available for metalation.
The use of a more basic lithium alkyl such as tert-butyllithium
may not require the use of a polar metalation promoter.
The polar compound promoters include a variety of tertiary
amines, bridgehead amine~, ethers, and metal alko~ides.
~21Ei~7~
- 12 -
The tertiary amines useful in the metalation step have three
saturated aliphatic hydrocarbon groups attached to each nitrogen
and include, for example:
(a) Chelating tertiary diamines, preferably those of the formula
(R )2N-C H2y~~N(R )2 in which each R2 can be the same or
different straight- or branched-chain alkyl group of any
chain length containing up to 20 carbon atoms or more all of
which are included herein and y can be any whole number from
2 to 10, and particularly the ethylene diamines in which all
alkyl substituents are the same. These include, for example:
tetramethylethylenediamine (which is preferred~, tetraethyl-
ethylenediamine, tetradecylenediamine, tetraoctylhexylenedi-
amine, tetra-(mixed alkyl) ethylenediamines, and the like.
(b) Cyclic diamines can be used, such as, for example, the
N,N,~',N'-tetraalkyl 1,2-diamino cyclohexanes, the N,~,N',N',-
tetraalkyl 1~4 diamino cyclohexanes, ~,N'-dimethylpiperazine,
and the like.
(c) The useful bridgehead diamines include, for example, sparteine,
triethylenediamine, and the like.
Tertiary monoamiDes such as triethylenediamine are generally
not as effective in the lithiation react-lon. However, bridgehead
monoamines such as l-azabicyclo~2.2.2~ octane and its substituted
homologs are effective.
Ethers and the alkali metal alkoxides are presently less
preferred than the chelating amines as activators for the me~alation
reaction due to somewhat lower levels of incorporation of functional
group containing compounds onto the copolymer backbone in the
subsequent grafting reaction.
Polar metalation promoters may be present ln an amount
sufficient to enable metalation to occur, e.g. amounts between
0,01 and 100 or more preferably between 0.1 and 10 and most
preferably between 1 and 3 equivalents per equivalent of lithium
alkyl.
7~
The equivalenes of lithlum employed for the desired amount of
lithiation generally range from such as 0.001 to 3 per vinyl-arene
unit in the copolymer, presently preferably 0.01 to 1.0 equivalents
per vinyl-arene unit in the copolymer to be modified. The molar
ratio of active lithium to the polar promoter can vary from such
as 0.01 to 10Ø A preferred ratio is 0.5.
The amount of alkyl lithium employed can be expressed in
terms of the Li/vinylarene molar ratio. This ratio may range from
a value of 1 (one lithium alkyl per vinylarene unit) to as low as
1 x 1~ 3 (1 lithium alkyl per 1000 vinylarene units).
In general, it is most desirable to carry out the lithiation
reaction in an inert solvent such as saturated hydrocarbons.
Aromatic solverlts such as benzene are lithiatable and may interfere
with the desired lithiation of the hydrogenated copolymer. The
solvent/copolymer weight ratio which is convenient generally is in
the range of about 5:1 to 20:1. Solvents such as chlorinated
hydrocarbons, ketones, and alcohols, should not be used because
they destroy the lithiating compound.
The process of lithiation can be carried out at temperatures
in the range of such as about -70 C to ~150 C, presently
preferably in the range of about 25 C to 80 C, the upper
temperatures being limited by the thermal stability of the lithium
compounds~ The lower temperatures are limited by considerations of
production cost, the cost of cooling these reactants becoming
high at low temperatures. The length of time necessary to complete
the lithiation and subsequent reactions is largely dependent upon
the mixing conditions and the temperature. Generally the time can
range from a few seconds to about 72 hours, presently preferably
from about 1 minute to 1 hour.
The next step in the process of preparing the modified block
copolymer is the treatment of the lithiated hydrogenated
copolymer, in solution, without quenching in any manner which
would destroy the lithium sites, with a species capable of reacting
w~th a lithium anion. These reactive species are selected
q3
- 14 -
from the class of molecules called electrophiles. The most preferred
electrophiles have been listed above in the section hereinbefore.
These electrophiles either contain or form upon reaction with the
polymer bound lithium anion the desired functional groups~ such
functional groups include but are not limited to
01
-C-O- carboxyl C-~R2 Amine
C-OH hydroxyl ~-NR2 Amide
C-OR ether C-SH Thiol
o
-C-R ~etone C-B(OR)2 Borane^containing
-C-H aldehyde C-Si- Silicone-containing
The process also includes further chemistry on the modified
block copolymer. For example, converting of a carboxylic acid salt
containing modified block copolymer to the carboxylic acid form
can be easily accomplished.
EXAMPLES
Example 1
The base polymer used in this example was an S-E¦B-S type
block copolymer (herein referred to as reactant polymer A).
Reactant polymer A had a molecular weight of about 50,000 and
contained 30% polystyrene.
In a typical experiment, 45.36 kg of a polymer cement
containing Polymer A in cyclohexane (5~ solids) was lithlated at
60 ~C using a diamine (eetramethylethylenediamine, TMEDA) promoted
sec-butyl-Li reagent (1.1 mol base, 1.8 mol promoter). A rapid
metalation reaction afford~d a thixotropic, semlsolid cement which
immobllized the reactor's stirring mechanism (auger type) within
3-4 minutes. An aliquot of the lithiated-polymer cement was
quenched with D20. The remainder was transferred through a 3.8 cm
diameter line to a vessel containing an excess of C02 (1.36 kg) in
g~ 73
- 15 -
tetrahydrofuran (THF). The carboxylated product was treated with
acetic acid (85 g, 1.4 mol) and finished by steam coagulation
affording over 1.81 kg of white, functionalized polymer crumb.
Analyses of the carboxylated product found 0.84% wt - C02H and
0.29% wt ~ CO2 - for a total polymer bound carboxylate content of
1.13% wt.
A deuterium (D) NMR analysis of the D20 treated aliquot found
the D resided primarily at aromatic sites, at meta and para
positions on the ring, ~90% of total D), with the remainder of the
tag or label being at either benzylic or allylic positions (10% of
total D~. The technique cannot discern between allylic and benzylic
locations. Thus, the label resided principally, at least 90%, and
most likely entirely in the polystyrene block of the polymer. We
infer Erom this labelling experiment that essentially all of the
lithiation reaction, at least 90%, occurred in the polystyrene
~lock. Therefore, essentially all of the carboxylation must occur
at these sites as well.
Eor this experiment, 50% of the reactant sec-butyl Li was
converted into polymer bound carboxylate as found in the product
(lithiation efficiency). The product, as finlshed, contained 7
parts of acid (-CO2H) to every 26 parts of salt (-CO2-).
Examples 2-14
Examples 2-14 were conducted as outlined in Example 1. Some
modifications were used as outlined in Table 1.
Reactant polymer B was similar to polymer A with the molecular
weight being about 67,000. Reactant polymer C was similar to
polymer A ~ith the ~olecular weight ~eing ahout 181,000 and a
polystyrene content of 33%. Reactant polymer D was an S-E/P type
of block copolymer with a total molecular weight of about 98,000
and a polystyrene content of 37%.
The lithiation of polymers A, B and C proceeded with a rapid
rise in viscosity in all examples. In some examples, the lithiated
product was allowed to digest for longer periods without stirring.
The lithiation of polymer D proceeded with no observable increase
in cement viscosity.
IL73
As found in Example 1, deuterium NMR analyses of D20 quenched
aliquots of the various products found the label to be
predominantly in the polystyrene block of the polymer. These
results are summari7ed in Table 2.
Each of the deuterated samples was analyzed by Gel Permeation
Chromatography. The resulting molecular weight information did not
differ significantly from that for the starting unmetalated
polymer. This indicates that the metalation technique did not
induce any degradation, for example, chain scission or crosslinking
in these polymers.
Control experiments using the reaction technique of Example 1
and S-rubber-S block copolymers where the rubber is substantially
unsaturated showed that these reactants were lithiated indiscri-
minately in both the styrene block (about 50%) and the rubber
block (about 50%). These randomly functionalized products were not
preferred.
~L2~09
,,
a~ ~ o r~ ~ o
1~- ~ O~ 00 ~ ~ ~ ~D
~~ ~ ~ ~ o ~ O ~ ~ 3
~ ~~ oo ~ u~ ~ ~ cn o~ ~D O~ CO G~ CO
E~ ~'4
E~ ~ .~ ~ ~ c~l O ~ ~ ~ 5
,,
o
b~ ~ ~ ~ ~ O O~ O ~ C~
~ ~ _~ o _~ o _l o o o o ~ o _
C~
V
C~
V ~ _I ~ ~D i ~ ~ ~ ~ C~ ~ ~ Ul
Z ;~ _ -I O O I O O O O O O O ~ O
,_1 H ~ a~ ¢
.5
~_ ~ ~
~i ~ '` '` '`
~ ~ ~ ~ O O O ~ C`l O O ~ O O O O O
a~z t~ ~ ~3 ~O ~O ~
E~
~ ~ O ~
zi g ;q ~3 ~ ~ 1 0 0 0 0
H ~ t~ ¦
~u ~ ~ ~ ~: ~C ~ m
td O E~
P~
~ ~ ~ ~ U~ O
- 18 -
TABLE II
Location of Deuterated Site
Example Location of Deuterium Label (Carboxylate)
Number Aromatic Benzylic, Allylic
(%) (%)
2 91 9
3 93 7
4 92 8
Example 15
The modified block copolymer in Example 14 was converted to
the carboxylic acid salt formed by the following procedure: 50 g of
polymer was dissolved in 500 g of a 90:10 mixture of cyclohexane:THF.
Next, 4.3 g of a 1 molar aqueous LiOH solution was added. The
mixture was allowed to stand 24 hours. The polymer was then recovered
by precipitztion with methanol and dried at sub-atmospheric pressure.
By IR analysis, the sample showed complete conversion of acid
functionality to lithium salt functionality. The absorbance band of
the salt occurs at 1560-1600 cm 1, while that of the acid occurs at
16~0 ~
Example 16
In this example, hydroxyl functionality was placed on the base
polymer. The base polymer used was Reactant Polymer B.
Base polymer (100 g) was dissolved in 100 ml of cyclohexane in
a glass reactor under an argon purge. 1.02 meq TMEDA per g of
polymer was then added. Impurities in the mixture were then removed
by titration with sec-butyllithium. The reactor contents were
heated to 50 C, and 0.51 meq of additional sec-butyllithium per g
of polymer were added. 1000 ml of distilled THF was added and this
solution was stirred at 25 ~C for 16 hours. This mixture was
maintained at 40-45 C for 70 minutes. Next, ethylene oxide was
bubbled into the vessel and the mixture was stirred for 10 minutes
at 45 ~C. Finally, 1 meq of HCl (in methanol) per g of polymer was
~6~ l73
- 19 -
added to the reactor. The polymer WAS recovered by coagulation into
2-propanol and washed with methanol. A portion of the polymer was
dried at sub-atmospheric pressure at 40 C.
In order to analy~e this hydroxylated polymer, thP OH func-
tionality was converted to acid by reaction with maleic anhydride
at 150-160 ~C in diisopropylbenzeneO The reaction product was
precipitated into me~hanol and washed with 70 C water to remove
unreacted maleic anhydride. IR measurement showed carbonyl bands at
1730 cm 1 characteristic of a maleic ester.
The polymer was then dried at sub-atmospheric pressure at 50
C. Titration for the half maleic acid ester using potassium
methoxide in methanol together with a phenolphthalein indicator
gave 0.18 meq acid per g polymer, showing that the original modified
block copolymer contained 0.18 meq OH groups per g polymer.
