U.S. patent number RE34,640 [Application Number 07/875,082] was granted by the patent office on 1994-06-14 for thermoplastic elastomers of isobutylene and process of preparation.
This patent grant is currently assigned to University of Akron. Invention is credited to William G. Hager, Gabor Kaszas, Joseph P. Kennedy, Judit E. Puskas.
United States Patent |
RE34,640 |
Kennedy , et al. |
June 14, 1994 |
Thermoplastic elastomers of isobutylene and process of
preparation
Abstract
Block copolymers compose a polyisobutylene rubbery soft segment
of M.sub.n of about 5,000 to above 500,000 and glassy hard segments
of M.sub.n of about 5,000 or higher and usually about 10,000 to
35,000 or more, are made by preparing a living polymer block of the
polyisobutylene and then polymerizing on said living
polyisobutylene block the glassy hard segments by adding thereto an
electron donor having a donor number of 15 to 50 and then adding
and polymerizing the monomers for the glassy hard segments. The
monomers for the glassy hard segments are styrene and its
derivatives and indene and its derivatives and mixtures
thereof.
Inventors: |
Kennedy; Joseph P. (Akron,
OH), Puskas; Judit E. (Corunna, CA), Kaszas;
Gabor (Corunna, CA), Hager; William G.
(Reynoldsburg, OH) |
Assignee: |
University of Akron (Akron,
OH)
|
Family
ID: |
23093233 |
Appl.
No.: |
07/875,082 |
Filed: |
April 28, 1992 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
285207 |
Dec 16, 1988 |
04946899 |
Aug 7, 1990 |
|
|
Current U.S.
Class: |
525/244; 525/219;
525/245; 525/249; 525/257; 525/262; 525/266; 525/268; 525/313;
525/314; 525/316 |
Current CPC
Class: |
C08F
297/06 (20130101); C08F 297/00 (20130101) |
Current International
Class: |
C08F
297/00 (20060101); C08F 297/06 (20060101); C08F
255/10 () |
Field of
Search: |
;525/244,245,251,255,258,259,261,262,268,319,249,266,313,314,316 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Seidleck; James J.
Assistant Examiner: Clark; W. R. H.
Attorney, Agent or Firm: Oldham, Oldham & Wilson Co.
Claims
What is claimed is:
1. A living polymerization process for preparing linear or
star-shaped block copolymers of isobutylene and another monomer
comprising .[.polymerization isobutylene alone or with monomer at a
temperature of about -10.degree. C. to -90.degree. C. in an
anhydrous system of said isobutylene or another monomer, a mixed
solvent, imitator and a metal halide selected from the metals of
tin, titanium, aluminum, boron, said polymerization system being
capable of producing an electron pair donor initiator having the
formula.].:
(.Iadd.a) forming a reaction mixture at a temperature of about
-10.degree. C. to -90.degree. C. in an anhydrous system of
isobutylene, a mixed solvent comprising a mixture of a
non-halogenated hydrocarbon solvent and a halogenated solvent, and
an initiator having the formula .Iaddend. ##STR3## in which
R.sub.1, R.sub.2 and R.sub.3 are alkyl, aryl, or aralkyl groups and
can be the same or different and .[.x.]. .Iadd.X .Iaddend.is
.Iadd.selected from the group consisting of .Iaddend.a carboxyl,
.Iadd.an .Iaddend.alkoxyl, .Iadd.an .Iaddend.hydroxyl .[.or.].
.Iadd.and a .Iaddend.halogen group, and i is a positive whole
number.[., said mixed solvent being formed of at least one
hydrocarbon or halohydrocarbon with or without an electron donor
pair solvent having a donor number of about 15 to 50, when x is
carboxyl or alkoxy; the mixed solvent being a mixture of
hydrocarbon and halohydrocarbon with or without said electron donor
pair solvent with said hydrocarbon or halohydrocarbon and when x is
hydroxyl or halogen, the mixed solvent must contain an electron
pair donor solvent of 15 to 50 donor number when said
polymerization of another monomer occurs in the presence of the
electron pair donor solvent, the mixed solvent and living
polyisobutylene, said another monomer being selected from at least
one of styrene, and its halo or alkyl styrenes, indene and
alkylated indenes..]..Iadd.;
(b) adding a metal halide wherein the metal in the metal halide is
selected from the group consisting of tin, titanium, aluminum, and
boron to initiate the isobutylene polymerization forming a living
polymer, except when X is the hydroxyl group or the halogen group
and the initiator does not form an in-situ electron pair donor by
an interaction with the metal halide, the reaction mixture is
formed by combining the mixed solvent, initiator, isobutylene and
an electron pair donor having a donor number, DN, from about 15 to
about 50, and then adding the metal halide;
(c) adding the electron pair donor, except when X is the hydroxyl
group or the halogen group, to form an electron pair donor with the
metal halide, the electron pair donor having a donor number, DN,
from about 15 to about 50, to obtain high blocking efficiency by
preventing side reactions involving splitting of protons from the
living polymer;
(d) adding at least one other monomer selected from the class
consisting of styrene, derivatives of styrene, indene, derivatives
of indene, and mixtures thereof, to the reaction mixture; and
(e) polymerizing the other monomer or mixture of other monomers to
form a block copolymer in which the polyisobutylene polymer
comprises the soft segment and the polymerized other monomer or
mixture of other monomers form the glassy blocks of the block
copolymer. .Iaddend.
2. The process according to claim 1 wherein said initiator forming
in situ electron pair donor is selected from the group consisting
of
2, methoxy-2-phenylpropane; 2-acetyl-2-phenylpropane;
1,4-di(2-methoxy-2-propyl)benzene;
1,4-di(2-acetyl-2-propyl)benzene;
1,3,5-tri(2-acetyl-2-propyl)benzene;
1,3,5-tri(2-methoxy-2-propyl)benzene;
3-tert.butyl-1,5-di(2-methoxy-2-propyl)benzene;
2-methoxy-2,4,4-trimethylpentane;
2-acetyl-2,4,4-trimethylpentane;
2,6-dimethoxy-2,4,4,6-tetramethylheptane and
2,6-diacetyl-2,4,4,6-tetramethylheptane; and wherein said initiator
not forming in situ electron pair donors is selected from the group
consisting of
2-chloro-2-phenylpropane;
1,4-di(2-chloro-2-propyl)benzene;
1,3,5-tri(2-chloro-2-propyl)benzene;
2-hydroxy-2-phenylpropane;
1,4-di(2-hydroxy-2-propyl)benzene;
1,3,5-tri(2-hydroxy-2-propyl)benzene;
2-chloro-2,4,4-trimethyl-pentane;
2,6-dichloro-2,4,4,6-tetramethylheptane;
2-hydroxy-2,4,4-trimethyl-pentane and
2,6-dihydroxy-2,4,4,6-tetramethylheptane.
3. The process according to claim 2 wherein said metal halide is
titanium tetrachloride or boron trichloride.
4. The process according to claim 3 wherein said electron pair
donor is selected from the class consisting of dimethyl sulfoxide,
dimethyl acetamide and hexamethyl phosphoramide.
5. The process according to claim 4 wherein the ratio of said metal
halide to said initiator on a molar basis, is from about 2 to 1 to
about 50 to 1; the ratio of said electron pair donor to said
initiator on a molar basis, is from about 1 to 10 to about 1 to 1;
the ratio of said electron pair donor to said metal halide is at
least 1 to 2; or the ratio of said electron pair donor plus said
initiator forming in situ electron pair donors combined with said
metal halide is at least 1 to 2; and the ratio of non-halogenated
hydrocarbon solvent, on a volume basis, is from about 4 to 1 to
about 1 to 1.
6. The process according to claim 5 wherein said hydrocarbon
solvent is a cycloalkane, and said halogenated hydrocarbon solvent
is a halogenated alkane.
7. The process according to claim 6 wherein said cycloalkane is
cyclohexane or methylcyclohexane or mixtures thereof, and said
halogenated alkane is selected from the group consisting of methyl
chloride, methylene chloride, and mixtures thereof.
8. The polymerization process according to claim 1 said other
monomer or mixture of other monomers is selected from the group
consisting of styrene and its derivatives consisting of normal or
branched alkyl or halogen substituents on the aromatic ring and
indene and its derivatives consisting of normal or branched alkyl
or halogen substituents on the aromatic ring.
9. The polymerization process according to claim 1 said other
monomer or mixture of other monomers is selected from the group
consisting of styrene, p-tert.-butylstyrene, p-methylstyrene,
p-chlorostyrene, indene and mixtures thereof.
10. The polymerization process according to claim 1 wherein a
proton scavenger is selected from the group consisting
2,6-di-tert.-butylpyridine, 4-methyl-2,6-di-tert.-butylpyridine,
1,8-bis(dimethylamino)-naphthalene and diisopropylethylamine and is
added to the polymerization mixture in the beginning of the
polymerization reaction.
11. The polymerization process according to claim 10 wherein said
proton scavenger is 2,6-di-tert.-butylpyridine.
12. The process according to claim 11 wherein the concentration of
said proton scavenger is at least equal to, or up to 1.5 times
higher than the concentration of moisture in the polymerization
system.
Description
Technical Field
This invention relates to block copolymers. More particularly, this
invention relates to thermoplastic elastomeric polymers (TPE)
having a central portion which exhibits rubbery properties and end
portions which possess a glassy character. Specifically, this
invention relates to block copolymers, and especially to
thermoplastic elastomeric products prepared by carbocationic
polymerization involving an initial homopolymerization of a monomer
to form a polymer capable of conferring elastomeric properties on
an ultimate product without curing. The homopolymerization is
followed by the subsequent addition of a monomer or a mixture of
monomers capable of forming endblock polymer or copolymer segments
which confer glassy properties on the ultimate block copolymer
product and the copolymerization of the latter monomer with the
homopolymer to form an ultimate product exhibiting both elastomeric
and thermoplastic properties.
Background of the Invention
Polymeric materials exhibiting both thermoplastic as well as
elastomeric characteristics have a variety of unique properties
which makes such materials valuable articles of commerce. Such
thermoplastic elastomers are block copolymers having the general
structure of ABA (linear triblock). A(BA).sub.n (linear alternating
block), or (AB).sub.n -X (radial block) where A is a thermoplastic
glassy block with a high glass transition temperature, while B is
an elastomeric block, and n is a positive whole number and X is the
initiator core or residue. The copolymers behave like vulcanized
rubbers at room temperature and like thermoplastic polymers at
higher temperatures. Thus, the materials can be melt extruded like
plastics, while retaining their beneficial rubbery features upon
cooling. This ability is not only of advantage during processing of
the polymers, but allows the materials to be reprocessed.
Furthermore, not only are such products fundamentally elastomeric
but they exhibit physical behavior similar to elastomers which have
been reinforced with reinforcing agents. In other words, the
products behave substantially in the same manner as vulcanized
rubbers, but without the need to subject them to vulcanization,
which is often impractical because of the nature of the product
being produced, for example, adhesives, coatings and elastic
threads.
Polymers having such dual nature have been known for some time but
have the product deficiencies indicated below in this section. One
such family of products, for example, being that prepared by
copolymerizing polystyrene with polybutadiene, is sold under the
trade name "Kraton" by Shell Oil Company. While the latter products
possess the desirable fundamental quality of properties described,
they also possess certain undesirable characteristics. For example,
their glass transition temperatures are undesirably low, in the
neighborhood of 90.degree. C., limiting the temperature environment
in which they can be used. In addition, the products possess an
undesirably high degree of unsaturation in their central polymer
block portion which makes them vulnerable to oxidative degradation
through exposure to air. While such degradation may be avoided by
subjecting the products to techniques which saturate their double
bonds, the additional processing is expensive. In a copending
application, Ser. No. 208,374, filed on 06/17/88 of the inventors
herein, a block copolymer is disclosed containing polyisobutylene
elastomeric midsegment and post-cyclized polyisoprene outer hard
segments having a glass transition temperature around 150.degree.
C. Though this latter copolymer is superior to Kraton in oxidative
stability and in regard to the higher glass transition temperature
of the outer blocks, the post cyclized outer segments still contain
unsaturation. Furthermore, the post-cyclization of the uncyclized
prepolymer entails undesirable expense and the post-cyclized
products reach desirable physical strength only after an extended
period of time.
Attempts have previously been made to synthesize fully saturated
polystyrene-polyisobutylene-polystyrene (Zs. Fodor, J. P. Kennedy,
T. Kelen and F. Tudos: J. Macromol.Sci.-Chem. (A24(7), 735 (1987))
and poly(.alpha.)
methylstyrene-polyisobutylene-poly(.alpha.)methylstyrene (J. P.
Kennedy, R. A. Smith; J.Polymer Sci., Polym.Chem.Ed., 18, 1539
(1980)) linear triblock copolymers. The final products, however,
were not pure but inhomogeneous, and exhibited very poor physical
properties, even after laborious separation procedures, due to the
nonuniform distribution of polystyrene in the final product. These
products cast as a film were so weak as to exhibit no tensile, much
less than 100 psi.
SUMMARY OF THE INVENTION
A first aspect of the invention, therefore, is to provide a process
by sequential monomer addition techniques for preparing block
copolymers which exhibit both thermoplastic and elastomeric
properties.
The second aspect of the invention is to prepare the elastomeric
section of thermoplastic elastomeric copolymers by living
polymerizations employing multifunctional polymerization initiator
systems.
A further aspect of this invention is to prepare new thermoplastic
elastomeric copolymers whose elastomeric section is saturated, and
thus is less susceptible to oxidation.
Yet another aspect of the invention is to prepare thermoplastic
elastomers whose outer glassy blocks exhibit relatively high glass
transition temperatures.
Another aspect of the invention is to prepare thermoplastic
elastomers whose outer glassy blocks are copolymers of two or more
monomers containing aromatic groups, thus the T.sub.g of the outer
blocks may be adjusted by varying the composition of the outer
glassy copolymer blocks.
Another aspect of this invention is to provide block copolymers in
which the elastomeric portion has a relatively narrow molecular
weight distribution.
The foregoing and other aspects of the invention, as it will become
apparent in the following disclosure of the invention, are provided
by a polymerization process for preparing block copolymers
comprising the following steps carried out at a temperature below
-40.degree. C. in the first phase, forming a living polyisobutylene
block of the desired molecular weight, functionally, and relatively
narrow molecular weight distribution (as disclosed in our
co-pending patent applications Ser. No. 07/189,774 filed 05/03/88;
and Ser. No. 208,374 filed 06/17/88) and in the second phase
polymerizing another monomer or mixtures of monomers on said living
polyisobutylene block to form end groups having aromatic groups by
adding an electron pair donor having a donor number from about 15
to about 50, sometimes hereinafter called an inherent electron
donor and the other monomer or mixtures of monomers to the reaction
mixture. Addition of the inherent electron pair donor is thought to
avoid undesirable side reactions and to assure complete blocking
from said living polyisobutylene midsection in the subsequent end
block polymerization step. The second or other monomer or mixture
of monomers consists of styrene, alkylated styrene, halostyrene,
indene and alkylated indene and like derivatives. Polymerizing said
second monomer or mixture of monomers according to our process
forms a diblock, triblock or a star-shaped block copolymers in
which said first polymer comprises the midblock and said second
monomer or mixture of monomers having ethylenically unsaturated
aromatic groups form the endblock or endblocks of said block
copolymer.
The foregoing and additional aspects of the invention are provided
by a triblock or a star-shaped block copolymer comprising a
polyisobutylene midblock and endblocks of polymerized styrene or
styrene derivative viz. ring alkylated styrene or ring halogenated
styrene or indene or indene derivative viz. alkylated indene or
their copolymers, wherein the ratio of weight average molecular
weight to number average molecular weight of said midblock is from
about 1.01 to about 1.5 wherein the ratio of average molecular
weight to number average molecular weight of said block copolymer
is from about 1.05 to about 2.0 and no more than about 3.0 with a
tensile of greater than 100 to 500 or 1000 or more.
DETAILED DESCRIPTION OF THE INVENTION
Thermoplastic elastomers containing elastomeric polyisobutylene
blocks are extremely useful materials due in part to the saturated
nature of their midblock segments. They exhibit a unique
combination of properties including a high degree of resistance to
penetration by either moisture or gases, together with a high
degree of thermal and oxidative stability. The products also
exhibit a self-reinforcing characteristic as a result of the fact
that the glassy blocks and the elastomeric blocks show phase
separation.
In preparing the thermoplastic elastomers of the invention the
polymerization reaction is conducted under conditions which would
avoid chain transfer and termination of the growing polymer chains.
Anhydrous conditions are essential and reactive impurities, such as
components containing active hydrogen atoms (water, alcohol and the
like) must be removed from both the monomer and solvents by the
well-known techniques. The temperature for the polymerization is
usually between -10.degree. and -90.degree. C., the preferred range
being between -40.degree. and -80.degree. C., although lower
temperatures may be employed if desired. In order to avoid moisture
condensation the reaction should be carried out under a dry inert
gas atmosphere, preferably nitrogen gas.
The midblock portion of the thermoplastic elastomers of the
invention is prepared by procedures disclosed in our co-pending
patent applications Ser. No. 07/189,774 filed 05/03/88 and
07/208,374 filed 06/17/88. Our two co-pending applications are
incorporated herein by reference. The functionality of the
initiators used for the preparation of the living polyisobutylene
midblock depends on the desired structure of the final product, for
example, for the preparation of a linear triblock copolymer
difunctional initiators, while for the preparation of a radial
block copolymers initiators having a functionality of three or more
should be used. As used herein "functionality" is meant to refer to
the number of active sites of the initiator capable of initiating
living isobutylene polymerization upon the addition of the
coinitiator of the general formula of MX.sub.n in which M is
titanium, aluminum, boron or tin; X is a halogen; and n is a
positive whole number. Any of the above Lewis acids of the formula
MX.sub.n may be used as coinitiators, however, some compounds are
preferred over others. For example, the aluminum and tin chlorides
function less efficiently in the process of the invention, while
titanium tetrachloride produces exceptional results and the latter
compound is, therefore, especially preferred.
The initiator components of the invention have the formula ##STR1##
in which R.sub.1, R.sub.2 and R.sub.3 are alkyl, aryl, or aralkyl
groups usually of 1 to about 20 and preferably 1 to 8 carbon atoms
and can be the same or different and X is a carboxyl, an alkoxyl, a
hydroxyl group, or a halogen, and i is a positive whole number, and
is used in conjunction with a Lewis acid component of the formula
MX.sub.n.
As previously indicated, the initiator of the type contemplated by
the invention may be tert-esters or tert-ethers producing in situ
electron pair donors upon the addition of the MX.sub.n, or
tert-hydroxyl or tert-halogen containing compounds that require the
purposeful addition of inherent electron pair donors so as to give
living polymerization systems. Suitable initiators are cumyl esters
of hydrocarbon acids, and alkyl cumyl ethers. Representative
initiators, for example, comprise compounds such as
2-acetyl-2-phenylpropane, i.e., cumyl acetate;
2-propionyl-2-phenylpropane, i.e., cumylmethyl-ether;
1,4-di(2-methoxy-2-propyl)benzene, i.e., di(cumylmethyl ether); the
cumyl halides, particularly the chlorides, i.e.,
2-chloro-2-phenylpropane, i.e., cumyl chloride;
1,4-di(2-chloro-2-propyl)benzene, i.e., di(cumylchloride);
1,3,5-tri(2-chloro-2-propyl)benzene, i.e., tri(cumylchloride); the
aliphatic halides, particularly the chlorides, i.e.,
2-chloro-2,4,4-trimethylpentane,
2,6-dichloro-2,4,4,6-tetramethylheptane; cumyl and aliphatic
hydroxyls such as 1,4-di(2-hydroxyl-2-propylbenzene) and
2,6-dihydroxyl-2,4,4,6-tetramethyl-heptane and similar compounds.
Among the preceeding, the polyfunctional compounds are particularly
preferred.
In selection of the solvent or solvent mixture the following
aspects, should be considered: (1) The selected solvent or solvent
mixture should preferably keep the polyisobutylene and the final
block copolymer in solution and (2) should provide a solvent medium
having some degree of polarity in order for the polymerization to
proceed at a reasonable rate. To fulfill this complex requirement a
mixture of nonpolar and polar solvent is preferred. Suitable
nonpolar solvent will include hydrocarbons and preferably aromatic
or cyclic hydrocarbons or mixtures thereof. Such compounds include,
for instance, methylcyclohexane, cyclohexane, toluene, carbon
disulfide and others. Appropriate polar solvents include
halogenated hydrocarbons, normal, branched chain or cyclic
hydrocarbons. Specific compounds include the preferred liquid ones
such as ethyl chloride, methylene chloride, methyl-chloride,
n-butyl chloride, chlorobenzene, and other chlorinated
hydrocarbons. Any of the above solvents may be used, however, some
compounds are preferred over others. For example, a mixture of
methylcyclohexane or cyclohexane with methylene chloride or methyl
chloride produces exceptional results and therefore, are especially
preferred. To achieve suitable polarity and solubility, it has been
found, for example, that the ratio of the nonpolar solvent to the
polar solvent, on a volume basis, should be from about 80/20 to
about 50/50. However, the use of a ratio of about 60/40 has been
found to provide particularly good results and the use of this
ratio is preferred.
Inasmuch as chain transfer or irreversible termination does not
occur during the synthesis of the living polyisobutylene midblock,
molecular weight control can be accomplished merely by adjusting
the relative amount of isobutylene and initiator present in the
reaction mixture. The polymer will continue to grow as long as
monomer is available for reaction.
After obtaining the living polyisobutylene midblock of desired
molecular weight and functionality, a suitable inherent electron
pair donor having a donor number from about 15 to about 50, such as
dimethyl acetamide or dimethyl sulfoxide is added to the reaction
mixture in about 1/1-1/10 molar ratio to the chain end
functionality to obtain high blocking efficiency, and to prevent
side reactions (such as intra- or intermolecular alkylation) in the
subsequent polymerization of the second monomer.
While not wishing to be bound by the theory, it is postulated that
when electron pair donors are added to the system, such donors
share their electron with the carbocations, thereby reducing their
reactivity. This in turn reduces the growing chains, latent
tendency to split off protons which can lead to chain transfer to
monomer, to react internally with themselves, or to react with
other chains, or to accept reaction-terminating halogen ions from
the counterions.
A further advantage of moderating the reactivity of the growing
chains by the addition of the electron donor is that the rate of
polymerization is reduced relative to the rate of crossover from
the di- or multifunctional polyisobutylene cation to the second
monomer added, favoring the formation of uniform block copolymers.
It is important therefore that the electron pair donor be selected
so that it has a sufficient donor number to produce the action
described.
The tendency of, or "strength" of the electron pair donor to share
its electrons with the growing cation has been referred to as its
"donor number", DN. The DN has been defined by Gutmann in the
article cited hereinafter and defined as the molar enthalpy value
for the interaction of the donor with SbCl.sub.5 as a reference
acceptor in a 10.sup.-3 M solution of dichloroethane. It has been
found that the DN of the electron pair donor should be at least 15
if the undesirable reactions referred to are to be avoided and the
advantageous preferred effect is to be achieved; while it should
not exceed a value of about 50 in order that practical reaction
rates can be achieved.
Among the numerous electron pair donors suitable for use with this
invention may be mentioned the following liquid ones such as ethyl
acetate, dimethyl acetamide, dimethyl formamide, dimethyl
sulfoxide, hexamethyl phosphoric triamide,
N-methyl-2-pyrrolidinone, pyridine, acetone, methylethyl ketone and
many others. Some typical electron pair donors and their donor
numbers are listed by Viktor Gutmann in the "Donor-Acceptor
Approach to Molecular Interactions", Plenum Press, New York
(1978).
The ratio of the electron pair donors to the growing active center
is normally in the range of 1/10 to 1/1--preferably 1/1, but the
ratio of growing center plus electron pair donors to the Lewis acid
should be at least 1/1 or preferably smaller (1/8) in order to main
a practical polymerization rate. In determination of the proper
ratios it should also be considered that certain initiators, such
as the ester or ether type, do form an in situ electron pair donor
in the first stage of polymerization, i.e., in the synthesis of the
polyisobutylene macrocation, and therefore its amount should be
taken into account. Furthermore, when initiators not forming an in
situ electron pair donor, such as the hydroxyl or halogen type
initiators are employed, inherent electron pair donors must be used
in the first stage of polymerization, i.e., in the synthesis of the
polyisobutylene macrocation, and therefore their amount should be
taken into account.
The addition of electron pair donors is followed by the addition of
the second monomer such as styrene or styrene derivative or indene
or indene derivative, or their mixtures. Among the numerous
monomers suitable for use with the invention may be mentioned the
following representative members: p-methylstyrene,
p-tert.-butylstyrene, p-chlorostyrene, indene, 6-methylindene,
5,7-dimethylindene, 4,6,7-trimethylindene and many others, or the
mixture of above monomers. For high temperature applications
monomers forming higher T.sub.g polymers such as polyindene
(T.sub.g =240.degree.-260.degree. C.) or polyindene derivatives are
preferred. The application of high T.sub.g polymers is also
desirable if the ultimate product should exhibit low tensile set.
In order to improve the processability of the ultimate block
copolymers alkylated derivatives of styrene or indene, such as
p-tert.-butylstyrene or p-methylstyrene or 5,7-dimethylindene are
preferred. Thermoplastic elastomers containing copolymer glassy
endblocks are new to the art and provide the end-users with
versatility. For instance, the T.sub.g of the endblocks can be
regulated by the compositions of the copolymer endblocks;
incorporation of halogen monomers provides improved flame
resistance; and processability can be improved by the incorporation
of monomers containing alkyl-substituted aromatic groups. Also,
relative high to high T.sub.g 's can be obtained such as
140.degree. to 260.degree. C.
Formation of the endblocks at the polyisobutylene ends commences
immediately upon addition of the aromatic monomer such as styrene
or indene or their derivatives, or their mixtures, to the reaction
mixture containing the mono-, di- or multifunctional
polyisobutylene cations. A slight amount of homopolymer may form
from the second monomer by initiation induced by protic impurities
(traces of moisture) present in the system but this may be
advantageous as it will act as a reinforcing filler. This
homopolymerization, however, my be prevented by the addition of
well-known proton scavengers such as 2,6-di-tert.-butylpyridine.
4-methyl-2,6-di-tert.-butylpyridine,
1,8-bis(dimethylamino)-naphtalene and diisopropylethyl amine.
The nature of proton scavengers are well known and described in the
Journal of Macromolecular Science Chemistry, vol. A 18, No. 1,
1982, pp. 1-152 or Carbocationic Polymerization by Joseph P.
Kennedy and Ernest Marechal at pgs. 32, 199, 449, 452 460 and 461
and incorporated by references herein. Proton scavengers should be
added to the reaction mixture before the addition of said second
monomer or mixture of monomers, or preferably before the addition
of said MX.sub.n. When the product desired has been achieved, the
reaction can be terminated, for example, by adding a nucleophilic
terminating agent such as methanol, ethanol, pyridine, ammonia, an
alkyl amine or water.
As is normally the case, product molecular weights are determined
by reaction time, temperature, concentration, the nature of the
reactants, and similar factors. Consequently, different reaction
conditions will produce different products. Synthesis of the
desired reaction product will be achieved, therefore, through
monitoring the course of the reaction by the examination of samples
taken periodically during the reaction, a technique widely employed
in the art and shown in the examples.
The properties of the block copolymers contemplated by the
invention will depend upon the relative lengths of the
polyisobutylene mid block portion as well as the amount and nature
of the second monomer, or mixtures of monomers, viz., the endblocks
(polystyrene or polyindene or their copolymers, or polymers and
copolymers formed from their derivatives). The elastomeric
properties of the ultimate block copolymer will depend on the
length of the midblock chain, with a molecular weight of from about
2,000 to about 30,000 tending to produce rather inelastic products.
On the other hand, when the midblock portion approaches a molecular
weight of M.sub.n =40,000 or above, the product will exhibit more
rubbery characteristics. The hard segments of the block copolymers
described will exhibit glass transition temperatures characteristic
for the given monomer, i.e., 95.degree. C. for polystyrene,
130.degree. C. for poly(p-tert.-butylstyrene) and
240.degree.-260.degree. C. for polyindene. Thus products suitable
for high temperature applications can be produced with polyindene
or polymers of indene derivatives. Furthermore, by the use of the
mixture of the appropriate monomers, copolymer hard segments can be
prepared. Thus the desired properties of the ultimate product can
be tailor made in a manner such as combining p-tert.-butylstyrene
with indene to provide high T.sub.g and good processability.
Moreover, the saturated nature of said block copolymers provide
oxidative stability and reprocessability in the absence of
stabilizers without deterioration of physical properties and are
useful as molding compositions alone or with other polymers or
modifiers of other polymers analogous to the uses of the Kraton
block copolymers. It should be noted that our block copolymers are
more stable than the Kraton block copolymers and where they contain
indene or its derivative blocks, have substantially higher glass
transition temperatures.
The block copolymers described in the preceding may be recovered
from the reaction mixtures by any of the usual techniques including
hot water coagulation in a stirred vessel, or by precipitation with
a non-solvent such as an alcohol or alcohol/acetone mixture,
followed by drying.
While not intended to be limiting in nature, the following examples
are illustrative and representative of the invention.
Example I
Production of the Living Polyisobutylene block:
A 250 ml round bottom flask equipped with a stirrer was charged
with 90 mls of methylcyclohexane, 60 mls of methyl chloride and
0.089 gm (4.times.10.sup.-4 mole) of dicumyl ether and 0.05 ml of
dimethyl sulfoxide. After cooling to -80.degree. C., 6 mls of
prechilled isobutylene were added, followed by the addition of 0.66
ml (6.times.10.sup.-3 mole) titanium tetrachloride. The
polymerization thus initiated was allowed to continue for 15
minutes. Thereafter, at 15 minute intervals, four additional
portions of 6 mls each of isobutylene were added. At this point, a
sample was withdrawn for GPC measurement which showed M.sub.n
=57,800 and M.sub.w /M.sub.n =1.18, I.sub.eff =95%.
Production of the Endblocks:
To the above living polyisobutylene mixture 0.05 ml of dimethyl
sulfoxide was introduced, followed by the addition of 20 mls of
styrene dissolved in 15 mls of methylcyclohexane and 10 mls of
methyl chloride, all prechilled to -80.degree. C. The
polymerization was allowed to proceed for 30 minutes before being
terminated by the addition of prechilled methanol. The product was
precipitated in methanol and the precipitate was dried to obtain
the ultimate block copolymers. Thus 37.5 gms of the copolymer was
formed with 95% conversion: 21.6 g of which was the PIB block and
15.9 gm was the polystyrene blocks, the polystyrene content being
28.4 mole % (42.4 wt%). .sup.1 H NMR spectroscopy showed 31 mole %
(45.5 wt %) polystyrene content. Subsequent examination by GPC
analysis showed the incorporation of styrene and distinctive
increase of the molecular weight relative to that of the PIB
dication while the molecular weight distribution remained
comparatively narrow (M.sub.w /M.sub.n =1.39 by PIB calibration)
indicating uniform distribution of styrene units in the product.
Thus, this block polymer can be either cast or compressed to form
films which are transparent and have tensile greater than 550, in
fact greater than 1000 psi and with elongation greater than 100%
and usually greater than 200%. Thus, these block copolymers are
truly elastomeric. The size of the polystyrene endblocks calculated
from yield data was about M.sub.n .congruent.21,000 on each side of
the PIB block.
The polymer sample then was compression molded at 150.degree.
C./50,000 psi and the transparent homogeneous film showed a tensile
strength at break, .delta.=1920 psi and elongation .epsilon.=540%.
The sample then was repeatedly molded without deterioration of the
above tensile data. Thus, these data demonstrate that this block
copolymer could be used to mold an article and the scrap could be
reused to mold a further article.
Example II
With the equipment and a procedure like that of the preceding
example, 90 mls of methylcyclohexane, 60 mls of methyl chloride and
0.089 gm (4.times.10.sup.-4 mole) of dicumyl ether and 0.05 ml of
dimethyl acetamide were combined and cooled to -80.degree. C. Six
mls of prechilled isobutylene were added followed by the addition
of 0.66 ml (6.times.10.sup.-3 mole) titanium tetrachloride,
polymerization was continued for 15 minutes at which time an
additional 6 mls of isobutylene were added. The polymerization was
continued for 15 minutes and a sample was withdrawn for GPC
measurement which showed M.sub.n =23,000 and M.sub.w /M.sub.n
=1.15, I.sub.eff =93%. Then 0.05 ml of dimethyl acetamide was
introduced, followed by the addition of 8 mls of styrene dissolved
in a mixture of 15 mls of methylcyclohexane and 10 mls of methyl
chloride, all prechilled to -80.degree. C. The polymerization was
allowed to proceed for 20 minutes before being terminated by the
addition of prechilled methanol. The product was then precipitated
in methanol and the precipitate dried. Thus, 17.9 gms of polymer
were recovered which represent 100% conversion, 8.6 g of which was
PIB and 9.3 gm was polystyrene, the polystyrene content being 36.8
mole % (51.9 wt %). .sup.1 H NMR spectroscopy showed 38 mole % (53
wt %) polystyrene content. Subsequent examination by GPC showed the
incorporation of styrene and distinctive increase of the molecular
weight relative to that of the PIB dication, while the molecular
weight distribution remained comparatively narrow (M.sub.w /M.sub.n
=1.43 by PIB calibration) indicating uniform distribution of
polystyrene in the block copolymer as distinguishing from the non
uniform and non homogeneous ones of the prior art. The size of the
polystyrene endblocks calculated from yield data was about M.sub.n
.congruent.10,000 one each side of the PIB block segment.
The polymer sample then was compression molded at 150.degree.
C./50,000 psi and showed a tensile strength at break, .delta.=1360
psi and elongation .epsilon.=310%. The sample then was repeatedly
molded without deterioration of the above tensile data. Thus, the
data demonstrate that this block copolymer could be used to mold an
article and that the scrap could be reused to mold a further
article.
Example III
With equipment and a procedure like that of the preceding example,
90 mls of methylcyclohexane, 60 mls of methyl chloride and 0.045 gm
(2.times.10.sup.-4 mole) of dicumyl ether and 0.025 ml of dimethyl
acetamide were combined and cooled to -80.degree. C. Six mls of
prechilled isobutylene were added, followed by the addition of 0.33
ml 3.times.10.sup.-3 mole) titanium tetrachloride and
polymerization was continued for 15 minutes, and thereafter at 15
minute intervals four additional portions of 6 mls of isobutylene
were added. A sample was withdrawn for GPC measurement which showed
M.sub.n =78,900 and M.sub.w /M.sub.n =31, I.sub.eff =130%. Then
0.025 ml of dimethyl acetamide was introduced, followed by the
addition of 20 mls of styrene dissolved in a mixture of 15 mls of
methylcyclohexane and 10 mls of methyl chloride, all prechilled to
-80.degree. C. The polymerization was allowed to proceed for 30
minutes before being terminated by the addition of prechilled
methanol. The product was then precipitated in methanol and the
precipitate was dried. Thus 38.4 gms of polymer were formed with
100% conversion, 21.6 g of which was PIB and 16.8 gm was
polystyrene, the polystyrene content being 29.6 mole % (43.8 wt %).
.sup.1 H NMR spectroscopy showed 19 mole % (30.3 wt %) polystyrene
content. Subsequent examination by GPC showed the incorporation of
styrene and a distinctive increase of the molecular weight relative
to that of the PIB dication, while the molecular weight
distribution remained comparatively narrow (M.sub.w /M.sub.n =1.43
by PIB calibration) indicating uniform distribution of styrene
units in the final product. The size of the polystyrene endblocks
calculated from yield data was about M.sub.n =30,000 on each side
of the PIB midblock.
The polymer sample then was compression molded at 150.degree.
C./50,000 psi and the homogeneous transparent film showed a tensile
strength at break, .delta.=1920 psi and elongation .epsilon.=720%.
The sample repeatedly was molded without deterioration of the above
tensile data. Thus, these data demonstrate that this block
copolymer could be used to mold an article and that the scrap could
be reused to mold a further article.
Example IV
With the equipment and a procedure like that of the preceding
example, 90 mls of methylcyclohexane, 60 mls of methyl chloride and
0.118 gm (4.times.10.sup.-4 mole) of tricumyl ether and 0.05 ml of
dimethyl acetamide were combined and cooled to -80.degree. C. Six
mls of prechilled isobutylene were added, followed by the addition
of 1 ml (1.times.10.sup.-2 mole) titanium tetrachloride and the
polymerization was continued for 15 minutes, and thereafter at 15
minute intervals, four additional portions of 6 mls of isobutylene
were added. A sample was withdrawn for GPC measurement which showed
M.sub.n =61,300 and M.sub.w /M.sub.n =1.33, I.sub.eff =88%. Then
0.05 ml of dimethyl acetamide was introduced, followed by the
addition of 20 mls of styrene dissolved in a mixture of 15 mls of
methylcyclohexane and 10 mls of methyl chloride, all prechilled to
-80.degree. C., and then the polymerization was allowed to proceed
for 30 minutes before being terminated by the addition of
prechilled methanol. The product was then precipitated in methanol
and the precipitate was dried. Thus, 37.5 gms of polymer was formed
with 100% conversion, 21.6 g of which was PIB and 15.9 gm is
polystyrene, the polystyrene content being 28.4 mole % (42.4 wt %).
.sup.1 H NMR analysis showed 25 mole % (38 wt %) polystyrene
content.
The product was a star-shaped block copolymer of the structure
shown: ##STR2## where X is the residue from the initiator, tricumyl
chloride. Subsequent examination by GPC analysis showed the
incorporation of styrene and a distinctive increase of the
molecular weight relative to that of the PIB trication, while the
molecular weight distribution remained comparatively narrow
(M.sub.w /M.sub.n =1.43 by PIB calibration) indicating uniform
distribution of polystyrene in the final product. The molecular
weight of the polystyrene endblocks calculated from yield data was
about M.sub.n .congruent.15,000 on the three arms of the PIB
midblock and essentially of equivalent length in each branch or end
block.
The polymer sample then was compression molded at 150.degree.
C./50,000 psi and showed a tensile strength at break, .delta.=1990
psi and elongation .epsilon.=390%. The sample repeatedly was molded
without deterioration of the above tensile data. Thus, these data
demonstrate that this block copolymer could be used to mold an
article and that the scrap would be reused to mold a further
article.
The next three examples (V-VII) demonstrate the advantageous
effects of 2,6-di-tert.-butylpyridine and related Proton scavengers
on the preparation of block copolymers.
Example V
With equipment and a procedure like that of the preceding example,
90 mls of methylcyclohexane, 60 mls of methyl chloride and 0.097 gm
(6.times.10.sup.-4 mole) of cumyl methyl ether were combined and
cooled to -80.degree. C. Six mls of prechilled isobutylene were
added, followed by the addition of 0.92 ml (8.times.10.sup.-3 mole)
titanium tetrachloride and the polymerization was continued for 15
minutes, and thereafter at 15 minute intervals five additional
portions of 6 mls of isobutylene were added. A sample was withdrawn
for GPC measurement showed M.sub.n =50,500 and M.sub.w /M.sub.n
=1.21, I.sub.eff =85%. Then 0.06 ml of dimethyl acetamide was
introduced, followed by the addition of 12 mls of styrene dissolved
in a mixture of 12 mls of methylcyclohexane and 12 mls of methyl
chloride, all prechilled to -80.degree. C. The polymerization was
allowed to proceed for 30 minutes before being terminated by the
addition of prechilled methanol. The product was then precipitated
in methanol and the precipitate was dried. Thus 36.8 gms of diblock
copolymer were formed with 100% conversion, 25.9 gms of diblock
copolymer were thus formed with 100% conversion, 25.9 g of which
was PIB and 10.9 gm was polystyrene, the polystyrene content being
18.5 mole % (30 wt %). After extraction of the homopolystyrene by
methyl-ethyl ketone .sup.1 H NMR spectroscopy showed 11.8 mole %
(19.9 wt %) polystyrene content. Subsequent examination by GPC
analysis showed the incorporation of styrene and a distinctive
increase of the molecular weight (M.sub.n =57,600; by PIB
calibration) relative to that of the PIB cation; the molecular
weight distribution remained comparatively narrow M.sub.w /M.sub.n
=1.57 by PIB calibration. The size of the polystyrene block
calculated from 1H NMR spectroscopy data was about M.sub.n
.congruent.12,500. The sample was compression molded at 150.degree.
C./15,000 psi for 30 minutes. It possessed low tensile strength as
expected. However, the diblock nature of the material renders it
useful as a compatabilizing agent for blends of polystyrene and
polyisobutylene, for example.
Example VI
With equipment and a procedure like that of the preceding example,
90 mls of methlcyclohexane, 60 mls of methyl chloride and 0.097 gm
(6.times.10.sup.-4) of cumyl methyl ether were combined and cooled
to -80.degree. C. Six mls of prechilled isobutylene were added,
followed by the addition of 0.92 ml (8.times.10.sup.-3) titanium
tetrachloride and polymerization was continued for 15 minutes, and
thereafter at 15 minute intervals five additional portions of 6 mls
of isobutylene were added. A sample was withdrawn for GPC
measurement which showed M.sub.n =50,300 and M.sub.w /M.sub.n
=1.17, I.sub.eff =86%. Then 0.06 ml of dimethyl acetamide and 0.20
ml of 2,6-di-tert.-butylpyridine (a proton trap) were introduced,
followed by the addition of 12 mls of styrene dissolved in a
mixture of 12 mls of methylcyclohexane and 12 mls of methyl
chloride, all prechilled to -80.degree. C. The polymerization was
allowed to proceed for 30 minutes before being terminated by the
addition of prechilled methanol. The product was then precipitated
in methanol and the precipitate was dried. Thus 36.8 gms of diblock
copolymer were formed with 100% conversion, 25.9 g of which was PIB
and 10.9 gm was polystyrene, the polystyrene content being 18.5
mole % (30 wt %). After extraction with methylethyl ketone, .sup.1
H NMR spectroscopy showed 17.7 mole % (28.5 wt. %) polystyrene
content. Subsequent examination by GPC analysis showed the
incorporation of styrene and a distinctive increase of the
molecular weight (M.sub.n =65,600; by PIB calibration) relative to
that of the PIB cation; the molecular weight distribution remained
comparatively narrow (M.sub.w /M.sub.n =1.57 by PIB calibration).
The size of the polystyrene block calculated from .sup.1 H NMR
spectroscopy data was about M.sub.n .congruent.20,100. These data
show that in the presence of the proton trap virtually all of the
styrene incorporated into the copolymer block, yielding higher
molecular weight polystyrene segment and negligible amount of
homopolystyrene.
The sample was compression molded at 150.degree. C./15,000 psi for
30 minutes. It possessed low tensile strength as expected. However,
the diblock nature of the material renders it useful as a
compatabilizing agent for blends of polystyrene and
polyisobutylene, for example.
Example VII
With equipment and a procedure like that of the preceding example,
90 mls of methylcyclohexane, 60 mls of methyl chloride and 0.088 gm
(4.times.10.sup.-4 mole) of dicumyl ether were combined and cooled
to -80.degree. C. Six mls of prechilled isobutylene were added,
followed by the addition of 0.7 ml (6.4.times.10.sup.-3 mole)
titanium tetrachloride and polymerization was continued for 15
minutes, and thereafter at 15 minute intervals four additional
portions of 6 mls of isobutylene were added. A sample was withdrawn
for GPC measurement which showed M.sub.n =61,900 and M.sub.w
M.sub.n =1.24, I.sub.eff =87%. Then 0.05 ml of dimethyl acetamide
and 0.20 ml of 2,6-di-tert.-butylpyridine (a proton trap) were
introduced, followed by the addition of 18 mls of styrene dissolved
in a mixture of 20 mls of methylcyclohexane and 20 mls of methyl
chloride, all prechilled to -80.degree. C. The polymerization was
allowed to proceed for 30 minutes before being terminated by the
addition of prechilled methanol. The product was then precipitated
in methanol and the precipitate was dried. Thus 36.1 gms of polymer
were formed with 95% conversion, 21.6 g of which was PIB and 14.5
gm was polystyrene, the polystyrene content being 26 mole % (40 wt
%). .sup.1 H NMR spectroscopy showed 22.5 mole % (35.0 wt %)
polystyrene content. Subsequent examination by GPC analysis showed
the incorporation of styrene and a distinctive increase of the
molecular weight relative to that of the PIB dication, while the
molecular weight distribution remained comparatively narrow
(M.sub.w /M.sub.n =1.43 by PIB calibration) indicating the uniform
distribution of styrene units in the block copolymer with the
styrene blocks on each end being essentially the same length. The
size of the polystyrene endblocks calculated from yield data was
about M.sub.n .congruent.18,100 on each side of the PIB
midblock.
The polymer sample then was compression molded at 150.degree.
C./50,000 psi and the transparent homogenous film showed a tensile
strength at break, .delta.=2720 psi and elongation .epsilon.=380%.
The compression molded film was transparent, indicating the absence
of homopolystyrene, in contrast to the haziness of the films made
from block copolymers prepared in the absence of the proton trap
2,6-di-tert.-butylpyridine. The sample repeatedly was molded
without deterioration of the above tensile data. Thus, these data
demonstrate that this block copolymer could be used to mold an
article and that the scrap could be reused to mold a further
article. It should be noted that the tensile strength of this film
is comparative to that of butadiene of styrene reinforced sulfur
cured film.
Example VIII
With the equipment and procedure like that of Example I, employing
exactly the same conditions (temperature, concentration, etc.) a
block copolymer was prepared, the only difference being that
p-tert.-butylstyrene was used to make the endblocks.
A sample withdrawn after the preparation of the PIB midblock showed
M.sub.n =57,200 and M.sub.w /M.sub.n =1.13 with 95% I.sub.eff. Thus
37.2 gms of polymer were recovered 21.6 gm of which was PIB and
15.6 gm was poly(p-tert.-butylstyrene), the
poly(p-tert.-butylstyrene) content being 20.2 mole % (42 wt %).
.sup.1 H NMR spectroscopy showed 15 mole % (33.5 wt %)
poly(p-tert.-butylstyrene) content. Subsequent examination by GPC
analysis showed the incorporation of p-tert.-butylstyrene and
distinctive increase of the molecular weight relative to that of
the PIB dication, while the molecular weight distribution remained
comparatively narrow (M.sub.w /M.sub.n =1.43 by PIB calibration).
The size of the poly(p-tert.-butylstyrene) endblocks calculated
from yield data is about M.sub.n .congruent.20,500 on each side of
the PIB midblock.
The polymer sample then was compression molded at 150.degree.
C./50,000 psi and showed a tensile strength at break, .delta.=1750
psi and elongation .epsilon.=470%. The sample repeatedly was molded
without deterioration of the above tensile data. The same sample
compression molded repeatedly at 170.degree. C./50,000 psi showed a
tensile strength at break, .delta.=1690 psi and elongation
.epsilon.=570%. Thus, these data demonstrate that this block
copolymer could be used to mold an article and that the scrap could
be reused to mold a further article.
Example IX
With the equipment and procedure like that of Example I, employing
exactly the same conditions (temperature, concentration, etc.) a
block copolymer was prepared, the only difference being that
altogether four 6 ml portions of isobutylene were used to prepare
the PIB midblock and that p-methylstyrene was used to make the
endblocks.
A sample withdrawn after the preparation of the PIB midblock showed
M.sub.n =42,100 and M.sub.w /M.sub.n= 1.23 with 95% I.sub.eff.
Thus, 32 gms of polymer were recovered 17.3 gm of which is PIB and
14.7 gm is poly(p-methylstyrene), the poly(p-methylstyrene) content
being 29 mole % (46.0 wt %). .sup.1 H NMR spectroscopy showed 32.9
mole % (51 wt %) poly(p-methylstyrene) content. Subsequent
examination by GPC analysis showed the incorporation of
p-methylstyrene and a distinctive increase of the molecular weight
relative to that of the PIB dication, while the molecular weight
distribution remained comparatively narrow (M.sub.w /M.sub.n =1.43
by PIB calibration). The size of the poly(p-methylstrene) endblocks
calculated from yield data was about M.sub.n .congruent.13,000 on
each side of the PIB midblock.
The polymer sample was then compression molded at 150.degree.
C./psi and showed a tensile strength at break, .delta.=1470 psi and
elongation .epsilon.=300%. The sample repeatedly was molded without
deterioration of the above tensile data. Thus, these data
demonstrate that this block copolymer could be used to mold an
article and that the scrap could be reused to mold a further
article.
Example X
With the equipment and procedure like that of Example I, employing
exactly the same conditions (temperature, concentration, etc.) a
block copolymer is prepared, the only difference being that
p-chlorostyrene is used to make the endblocks.
A sample withdrawn after the preparation of the PIB midblock shows
M.sub.n =57,200 and M.sub.w /M.sub.n =1.13 with 95%. I.sub.eff.
Examination by GPC analysis shows the incorporation of
p-chloro-styrene and a distinctive increase of the molecular weight
relative to that of the PIB dication, while the molecular weight
distribution remains comparatively narrow.
Incorporation of halogen substituents on the glassy outer blocks
confers improved flame resistance to the final product.
Example XI
With the equipment and procedure like that of Example I, employing
exactly the same conditions (temperature, concentration, etc.) a
block copolymer was prepared, the only difference being that
altogether four 6 ml portions of isobutylene were used to prepare
the PIB midblock and that 12 mls of indene were used to make the
endblocks.
A sample withdrawn after the preparation of the PIB midblock shows
M.sub.n =42,600 and M.sub.w /M.sub.n =1.24 with 95% I.sub.eff. Thus
22.7 gms of polymer are recovered 17.2 gm of which was PIB and 5.5
gm was polyindene, the polyindene content being 13.2 mole % (23.9
wt %). .sup.1 H NMR spectroscopy showed 17.4 mole % (29 wt %)
polyindene content. Subsequent examination by GPC showed the
incorporation of indene and a distinctive increase of the molecular
weight relative to that of the PIB dication, while the molecular
weight distribution remained comparatively narrow (M.sub.w /M.sub.n
=1.50 by PIB calibration). The size of the polyindene endblocks
calculated from yield data is about M.sub.n .congruent.6900 on each
side of the PIB midblock.
Tensile tests were performed on specimens prepared from films cast
from carbontetrachloride, dried at room temperature for 24 hours at
50.degree. C. in a vacuum oven for 12 hours, showing a tensile
strength at break .delta.=1800 psi and ultimate elongation
.epsilon.=540%.
Example XII
With the equipment and procedure like that of Example I, employing
exactly the same conditions (temperature, concentration, etc.) a
block copolymer was prepared, the only difference being that the
mixture of 8.3 gms indene and 11.7 gms p-tert.-butylstyrene
dissolved in 10 mls of methycyclohexane and 10 mls of
methylchloride, combined with 0.2 ml 2,6-di-tert.-butylpyrinide,
all prechilled, were used to make the endblocks.
A sample withdrawn after the preparation of the PIB midblock showed
M.sub.n =57,400 and M.sub.w / n=1.34 with 88% I.sub.eff. Thus 38.8
gms of polymer were recovered with 93% conversion, 21.6 gm of which
was PIB and 18.6 gm was poly(indene-co-p-tert.-butylstyrene), the
hard block content being 15.7 mole % (48 wt %). Subsequent
examination by GPC showed the incorporation of glassy copolymer and
distinctive increase of the molecular weight relative to that of
the PIB dication, while the molecular weight distribution remained
comparatively narrow (M.sub.w /M.sub.n =1.46 by PIB calibration).
The size of the glassy copolymer endblocks calculated from yield
data is about M.sub.n .congruent.25,000 on each side of the PIB
midblock.
Differential Scanning Calorimetry (DSC) gave a single T.sub.g
=170.degree. C. for the copolymer endblocks, in between the T.sub.g
s of the polymers of the individual aromatic monomers, polyindene
and poly(p-tert.-butylstyrene) (T.sub.g -240.degree.-260.degree. C.
and 130.degree. C., respectively). A film cast from CCl.sub.4
solution and subsequently dried in vacuum showed a tensile strength
at break .delta.=2850 psi and ultimate elongation .epsilon.=390%.
Thus, these data demonstrate that a block copolymer can be designed
for a wide variety of end use temperatures, while maintaining the
valuable characteristics of the previous examples such as a T.sub.g
of about 130.degree.-260.degree. C. to greater than 130.degree. C.
and preferably 150.degree. to 260.degree. C.
Example XIII
With the equipment and procedure like that of Example I, employing
exactly the same conditions (temperature, concentration, etc.) a
block copolymer is prepared, the only difference being that the
mixture of 8.3 gms p-chlorostyrene and 11.7 gms p-methylstyrene
dissolved in 10 mls of methylcyclohexane and 10 mls of
methylchloride, combined with 0.2 ml 2,6-di-tert.-butylpyridine,
all prechilled, are used to make the endblocks.
A sample withdrawn after the preparation of the PIB midblock shows
M.sub.n =57,400 and M.sub.w /M.sub.n =1.34 with 88% I.sub.eff.
Examination of the final product by GPC shows the incorporation of
glassy copolymer and a distinctive increase of the molecular weight
relative to that of the PIB dication, while the molecular weight
distribution remains comparatively narrow confirming the formation
of block copolymers. .sup.1 H NMR spectroscopy shows the
incorporation of p-chlorostyrene and p-methylstyrene into the final
product. The incorporation of halogen substituents onto the glassy
endblocks confers improved flame resistance of the final
product.
Example XIV
A 500 ml round bottom flask equipped with a stirrer and cooled to
-40.degree. C. was charged with 200 ml methyl chloride, 1.872 g
(0.01 mole) 2,6-dihydroxy-2,4,4,6-tetramethylheptane, 1.8 ml
dimethylacetamide, 34 ml isobutylene and the polymerization was
started by the addition of 12 ml BCl.sub.3. The polymerization was
allowed to continue for 2.5 hrs. At this point, a sample was
withdrawn for GPC measurement which showed M.sub.n =2420 and
M.sub.w /M.sub.n= 1.16, I.sub.eff =95%. To the above mixture 20 mls
of styrene dissolved in 20 mls of CH.sub.3 Cl and prechilled to
-40.degree. C. are added and the polymerization is allowed to
continue for 1 more hour before being terminated by the addition of
prechilled methanol. The product is precipitated in methanol and
the precipitate is dried in vacuo at room temperature to obtain the
ultimate block copolymers. Examination by GPC analysis shows
styrene incorporation and a distinctive increase of the molecular
weight, confirming the formation of block copolymer.
Example XV
A 500 ml round bottom flask equipped with a stirrer and cooled to
-60.degree. C. was charged with 200 ml methyl chloride, 1.16
(5.times.10.sup.-3 mole) 1,4-di(2-chloro-2-propyl) benzene, 0.7 ml
dimethyl sulfoxide, 15 ml isobutylene and polymerization was
started by the addition of 8 ml BCl.sub.3. The polymerization was
allowed to continue for 2.5 hrs. At this point, a sample was
withdrawn for GPC measurement which showed M.sub.n =2570 and
Mw/Mn=1.14, Ieff=97%. To the above mixture 20 mls of styrene
dissolved in 20 mls of CH.sub.3 Cl and prechilled to -60.degree. C.
are added and the polymerization is allowed to continue for 1 more
hour before being terminated by the addition of prechilled
methanol. The product is precipitated in methanol and the
precipitate is dried in vacuo at room temperature to obtain the
ultimate block copolymer. Subsequent examination by GPC analysis
shows styrene incorporation and a distinctive increase of the
molecular weight, confirming the formation of block copolymer.
Example XVI
A 250 ml round bottom flask equipped with a stirrer and cooled to
-80.degree. C. was charged with 90 ml methylcyclohexane, 60 ml
CH.sub.3 Cl, 0.35 ml (2.1.times.10.sup.-3 mole)
2-chloro-2,4,4-trimethylpentane, 0.15 ml dimethyl acetamide and
1.75 ml TiCl.sub.4, followed by the addition of 10 ml isobutylene.
The polymerization thus initiated was allowed to continue for 10
minutes. Thereafter, at 10 min. intervals, three additional
portions of 10 mls each of isobutylene were added. At this point, a
sample was withdrawn for GPC measurement which showed Mn=15740 and
Mw/Mn=1.09 Ieff=98%. At this point 20 mls of styrene dissolved in
20 mls of methylcyclohexane and prechilled to -80.degree. C. are
added and the polymerization is allowed to continue for 1 more hour
before being terminated by the addition of prechilled methanol. The
product is precipitated in methanol and the precipitate is dried in
vacuo at room temperature to obtain the ultimate block copolymers.
Examination by GPC analysis shows styrene incorporation and a
distinctive increase of the molecular weight, confirming the
formation of block copolymer.
Example XVII
A 250 ml round bottom flask equipped with a stirrer and cooled to
-80.degree. C. is charged with 90 ml methylcyclohexane, 60 ml
CH.sub.3 Cl, 0.43 ml (2.45.times.10.sup.-3 mole)
2-acetyl-2-phenylpropane and 14 ml isobutylene, followed by the
addition of 1.1 ml TiCl.sub.4. The polymerization thus initiated is
allowed to continue for 15 minutes. Thereafter, at 15 min.
intervals, two additional portions of 14 mls each of isobutylene
are added. At this point, 0.36 ml (2.times.10.sup.-3 mole)
hexamethylphosphoramide of DN=50 is added followed by the addition
of 20 mls of styrene dissolved in 20 mls of methylcyclohexane
prechilled to -80.degree. C. The polymerization is allowed to
continue for 1 more hour before being terminated by the addition of
prechilled methanol. The product is precipitated in methanol and
the precipitate is dried in vacuo at room temperature to obtain the
ultimate block copolymers. Subsequent examination by GPC analysis
shows the styrene incorporation and a distinctive increase of the
molecular weight, confirming the formation of block copolymer.
Table I shows further physical properties of films made from block
copolymers of Examples I to IV and VII, VIII, VIII**, IX, XI and
XII. All the films were made by compression molding at 150.degree.
C. and 50,000 psi for 30 minutes except the ones designated VIII**
and XI. VIII** was made from a sample of the copolymer Example VIII
by compression molding at 170.degree. C. and 50,000 psi for 30
minutes, and XI and XII were made by casting from carbon
tetrachloride as described in Example XI.
The indene in examples XI and XII may be replaced with
5,7-dimethylidene or related indene derivative and the methods of
examples XI and XII repeated to give a block copolymer having a
midblock of polyisobutylene and end blocks derived from
polymerization of 5,7-dimethylindene (example XI) or
copolymerization of 5,7-dimethylidene and a styrene derivative
(Example XII) or indene derivative.
TABLE I
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Physical Properties of Film Formed from the Polymers Tear Melt Flow
Polymers Strength Shore index Tensile Set Modulus of Die C Hardness
200.degree. C. 5 kg % 100% 200% 300% Tensile Values Type of Example
lb/in A-2 g/10 min 250% 130% psi psi psi (pm) (%) end
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segment I 40 0.3 7 130 160 270 1920 540 St II 199 80 13.3 -- 33 510
870 1280 1340 310 St III 76 33 0.0 8 -- 100 125 190 1920 720 St IV
130 54 0.4 16 -- 270 530 1240 1990 390 St (radial) VII* 280 990 --
1470 300 p-Me-St VIII 120 52 27.0 14 -- 180 270 630 1730 470
p-t-Bu-St VIII** 53 -- -- -- 240 310 540 1690 540 p-t-Bu-St IX 9
140 190 370 1800 540 Indent XI 3 230 720 1740 2720 380 St XII 610
1110 2080 2830 390 Indent/p-t-Bu-St copolymer
__________________________________________________________________________
*Is the presence of 3octyl-butylpyridine **After repeated remolding
at 170.degree./30,000 pm
The block copolymers of this invention are characterized by their
uniformity and homogeneity in the matrix of the polymer with the
M.sub.w /M.sub.n being essentially 1.05 to 2.5 and preferably 1.5
so the film and molded products in uncured state will exhibit a
tensile of at least about 500 to 2500 and elongation greater than
100 and preferably 300 to 500%. Analysis indicates the end blocks
are essentially equal and preferably greater than 5-10,000 for
(heat) results.
While in accordance with the patent statues only the best mode and
preferred embodiment of the invention has been illustrated and
described in detail, it is to be understood that the invention is
not limited thereto or thereby, but that the scope of the invention
is defined by the appended claims.
* * * * *