U.S. patent application number 10/278310 was filed with the patent office on 2003-03-13 for star-branched polymer with dendrimer core.
Invention is credited to Agarwal, Pawan Kumar, Frechet, Jean M. J., Haque, Shah A., Wang, Hsien-Chang, Wang, Yu Feng.
Application Number | 20030050433 10/278310 |
Document ID | / |
Family ID | 26728600 |
Filed Date | 2003-03-13 |
United States Patent
Application |
20030050433 |
Kind Code |
A1 |
Agarwal, Pawan Kumar ; et
al. |
March 13, 2003 |
Star-branched polymer with dendrimer core
Abstract
Polyisobutylene (PIB) functionalized with terminal reactive
unsaturation is disclosed. Carbocationically polymerized
monohalogen-terminated PIB is dehydrohalogenated in a hydrocarbon
solvent using an alkoxide of the formula RO-M wherein R is alkyl of
at least 5 carbon atoms and M is alkali metal. The PIB obtained has
terminal unsaturation which is 100% in the reactive `exo` form
which can be converted to succinic anhydride groups (PIB-SA) by the
ene reaction with maleic anhydride. The PIB-SA is reactive with
amine functional dendrimers to obtain a star-branched polymer
having a dendrimer core and PIB branches joined by succinimide
linkages. Blends of the star-branched polymer with polypropylene
have improved energy absorption properties and controllable
moisture/oxygen permeabilities useful in films.
Inventors: |
Agarwal, Pawan Kumar;
(Houston, TX) ; Wang, Hsien-Chang; (Bellaire,
TX) ; Wang, Yu Feng; (Houston, TX) ; Frechet,
Jean M. J.; (Oakland, CA) ; Haque, Shah A.;
(Houston, TX) |
Correspondence
Address: |
EXXONMOBIL CHEMICAL COMPANY
P O BOX 2149
BAYTOWN
TX
77522-2149
US
|
Family ID: |
26728600 |
Appl. No.: |
10/278310 |
Filed: |
October 23, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10278310 |
Oct 23, 2002 |
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09777398 |
Feb 6, 2001 |
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09777398 |
Feb 6, 2001 |
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09100271 |
Jun 19, 1998 |
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6228978 |
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60050727 |
Jun 25, 1997 |
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Current U.S.
Class: |
528/363 ;
524/252; 525/314; 525/387; 526/314; 526/333 |
Current CPC
Class: |
C08F 8/46 20130101; C08G
83/003 20130101; C08G 83/001 20130101; C08G 81/02 20130101; C08F
8/46 20130101; C08F 8/26 20130101; C08F 110/10 20130101; C08G
81/024 20130101; C08F 110/10 20130101; C08F 8/26 20130101; C08F
8/26 20130101; C08F 2810/40 20130101; C08G 81/00 20130101; C08F
2810/30 20130101 |
Class at
Publication: |
528/363 ;
525/387; 525/314; 524/252; 526/314; 526/333 |
International
Class: |
C08G 073/00 |
Claims
We claim:
1. A method for preparing polyisoolefins comprising the steps of:
(a) dehydrohalogenating a halogen-terminated polyisoolefin in a
hydrocarbon solvent in the presence of alkoxide of the formula RO-M
wherein R is alkyl of at least 5 carbon atoms and M is alkali
metal; and (b) recovering polyisolefin having terminal
unsaturation.
2. The method of claim 1 wherein the dehydrohalogenation step (a)
obtains polyisobutylene having a terminal double bond chain end in
`exo` form essentially free of `endo` form.
3. The method of claim 2 wherein the polyisoolefin is
monohalogen-terminated.
4. The method of claim 1 wherein the alkoxide is t-pentoxide.
5. The method of claim 4 wherein the alkoxide is potassium
t-pentoxide.
6. The method of claim 1 wherein the isoolefin has from 4 to about
12 carbon atoms.
7. The method of claim 6 wherein the isoolefin is isobutylene.
8. Polyisoolefin having a terminal double bond chain end in `exo`
form essentially free of `endo` form.
9. The polyisoolefin of claim 8 wherein the polyisoolefin comprises
polyisobutylene.
10. The polyisoolefin of claim 9 having a molecular weight from 500
to 25 500,000.
11. The polyisoolefin of claim 10 having a molecular weight of 500
to 30,000.
12. The polyisoolefin of claim 11 having a molecular weight of 500
to 20,000.
13. The polyisoolefin of claim 10 having a molecular weight of
20,000 to 500,000.
14. A method for preparing functionalized polyisoolefins comprising
the steps of: (a) dehydrohalogenating a halogen-terminated
polyisoolefin in a hydrocarbon solvent in the presence of alkoxide
of the formula RO-M wherein R is alkyl of at least 5 carbon atoms
and M is alkali metal; (b) reacting the product from step (a) with
maleic anhydride, and (c) recovering PIB-SA.
15. A method for preparing a hydrolytically stable star-branched
polymeric material having a dendrimer core and polyolefin branches,
comprising the steps of: (a) reacting a functionalized polyolefin
with a hydrolytically stable dendrimer having primary amine
functionality in an outer core, and (b) recovering star-branched
polymeric material.
16. The star-branched polymeric material prepared by the method of
claim 15.
17. A hydrolytically stable star branched polymeric material
comprising a hydrolytically stable dendrimer core with branches of
polyolefin.
18. The star branched polymeric material of claim 17 wherein the
polyolefin is a polyisoolefin.
19. The star-branched material of claim 18 wherein the
polyisoolefin is polyisobutylene.
20. The star branched polymeric material of claim 19 wherein at
least two polyisobutylene branches have different molecular
weights.
21. The star branched polymeric material of claim 19 wherein the
polyisobutylene branches have a molecular weight between 500 and
20,000.
22. The star branched polymeric material of claim 17 comprising a
mixture of dendrimer cores of at least 2 generations.
23. The star branched polymeric material of claim 19 also
comprising branches of polyethylene, polypropylene or
ethylene-propylene copolymer.
24. The star branched polymeric material of claim 17 wherein the
polyolefin is a alpha-olefin polymer.
25. A composition comprising a blend of polyalpha-olefins with a
star-branched polymer comprising a hydrolytically stable dendrimer
core with branches of a polyisoolefin, polyalpha-olefins or a
mixture of polyisoolefins and polyalpha-olefins.
26. The composition of claim 25 wherein polyalpha-olefin is
selected from polyethylene, polypropylene, ethylene-propylene
copolymers, and polyisobutylene.
27. The composition of claim 25 wherein the polyolefin is
polypropylene prepared with a metallocene based catalyst.
28. A film comprising polyolefin blended with a star branched
polymeric material comprising a hydrophilic dendrimer core with
branches comprising a polyisoolefin.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional application of U.S. Ser.
No. 09/777,398, filed Feb. 6, 2001, which is a divisional
application of of U.S. Ser. No. 5 09/100,271, filed on Jun. 19,
1998, U.S. Pat. No. 6,228,978, which is based on provisional
application U.S. Serial No. 60/050,727, filed on Jun. 25, 1997.
FIELD OF THE INVENTION
[0002] The present invention relates to a method for preparing
polyisoolefins having exclusive `exo` terminal double bond chain
ends, the polyisoolefins having exclusive `exo` terminal double
bonds, a method for preparing a star-branched polymeric material
from the polyisoolefin and a dendrimer, and the functionalized
polyisobutylenes and the star-branched polymeric materials prepared
by these methods. The present invention also relates to blends of
polyolefins and the star-branched polymer, and films and fibers
made from these blends. The present invention also relates to a
method for preparing star-branched polymeric material from a
polyolefin and a hydrolytically stable dendrimer and the star
branched material prepared by this method.
BACKGROUND OF THE INVENTION
[0003] Dendrimers are well defined globular molecules. These are
generally prepared by stepwise or reiterative reaction of
multifunctional monomers to obtain a branched structure. In U.S.
Pat. No. 5,530,092, for example, the repetition of double Michael
addition of acrylonitrile starting with a primary diamine followed
by hydrogenation obtains two primary amines for each initial amine.
This doubles the number of primary amine groups. Thus, beginning
with a diamine, the first generation dendrimer (G1) has four
primary amines; the second generation (G2) has eight primary
amines; the third generation (G3) has sixteen primary amines; the
fourth generation (G4) has thirty-two primary amines; the fifth
generation (G5) has sixty-four primary amines in the outer shell,
and so on. These polyamine dendrimers are said to be stable to
degradation through hydrolysis reactions.
[0004] Amine-terminated polyamidoamine, polyethyleneimine and
polypropyleneimine dendrimers are also known, for example, from
U.S. Pat. No. 5,393,797; 5,393,795; 5,560,929; and 5,387,617, all
to Hedstrand et al.
[0005] Polyisobutenyl succinimide-polyamidoamine dendrimer
star-branched polymers obtained by reacting second generation
polyamidoamine dendrimers with polyisobutenyl succinic anhydride
are disclosed in Migdal's U.S. Pat. No. 4,938,885 [to Migdal].
These polymers are said to have dispersancy powers in lubricating
oils and to exhibit antioxidant activity. However, these products
are not hydrolytically stable.
[0006] U.S. Pat. No. 5,316,973 discloses telechelic olefin polymers
such as telechelic diolefin polyisobutylene prepared by refluxing
dihalogen polyisobutylene in tetrahydrofuran with a strong base
such as potassium t-butoxide. This is said to produce a product
which has .sup.1H NMR spectroscopy at 60 MHz consistent with a
terminal vinylene functionality of 2.0.
[0007] Boerzel et al., U.S. Pat. No. 4,152,499, discloses
polyisobutylene said to contain a proportion of double bonds
reactive with maleic anhydride of from 60 to 90 percent of the
double bonds present in the polyisobutylene. The polyisobutylenes
are prepared using a boron trifluoride polymerization initiator
with a short polymerization time.
[0008] Bronstert et al., U.S. Pat. No. 4,599,433, discloses the
preparation of polyisobutylene-succinic anhydrides with titanium,
zirconium or vanadium alkoxides as catalysts which are said to
isomerize polyisobutylene during the reaction making it more
reactive with the maleic anhydride. The polyisobutylene-succinic
anhydride adduct is in turn reacted with a polyamine to obtain a
lubricating oil additive.
SUMMARY OF THE INVENTION
[0009] The present invention arises, in part, from a method for
preparing polyisobutylene having reactive terminal vinylidene
groups. The process involves dehydrohalogenating halogen-terminated
polyisobutylene in a hydrocarbon solvent using a metal alkoxide
soluble in the hydrocarbon solvent. This method does not require
tetrahydrofuran (THF) as a solvent. This obtains a polyisobutylene
terminated with an unsaturated end group which is in the reactive
`exo` form, and free of the corresponding `endo` form. This method
avoids the use of the undesirable tetrahydrofuran as a solvent. The
presence of tetrahydrofuran renders the dehydrohalogenation
reaction insufficiently stereospecific and introduces the
possibility of peroxide formation.
[0010] In one aspect, the present invention comprises a method for
preparing a polyisoolefin having double bond chain ends exclusively
in the `exo` form. The method includes the step of
dehydrohalogenating the halogen-terminated polyisoolefin in a
hydrocarbon solvent in the presence of hydrocarbon-soluble
alkoxide. The halogen-terminated polyisoolefin is generally
obtained by carbocationically polymerizing the isoolefin in the
presence of a halogenating initiator according to techniques well
known in the art to obtain halogen-terminated polyisoolefin. The
preferred alkoxides are represented by the formula RO-M wherein R
is alkyl of at least 5 carbon atoms and M is alkali metal. The
polyisoolefin obtained from the carbocationic polymerization
process can be telechelic, or in one embodiment is
monohalogen-terminated. The isoolefin preferably has from 4 to
about 12 carbon atoms, and more preferably is isobutylene. The
alkoxide is preferably a branched alkoxide, more preferably
tertiary-pentoxide (t-pentoxide), and the alkali metal can be one
of lithium, sodium, cesium, rubidium, preferably potassium. The
solvent should be essentially free of tetrahydrofuran. The method
thus effected in accordance with the invention obtains
polyisobutylene having a terminal double bond chain end in `exo`
form, essentially free of `endo` form.
[0011] In another aspect, the invention comprises a method for
preparing a star-branched polymeric material having a hydrophilic
dendrimer core and hydrophobic polyolefin branches. The method
includes reacting polyisoolefin-succinic anhydride with a dendrimer
having primary amine functionality. The polyisoolefin-succinic
anhydride is preferably polyisobutylene-succinic anhydride (PIBSA),
most preferably prepared by the steps of: (1) carbocationically
polymerizing isobutylene in the presence of a halogenating
initiator, such as 2,4,4-trimethylpentyl chloride, to obtain
monohalogen-terminated polyisobutylene; (2) dehydrohalogenating the
monohalogen-terminated polyisobutylene in a hydrocarbon solvent in
the presence of soluble alkoxide represented by the formula
RO-M.sub.2, R being an alkyl of at least 5 carbon atoms and M being
an alkali metal; and (3) functionalizing the dehydrohalogenated
polyisobutylene with maleic anhydride.
[0012] The star-branched polymer preparation preferably includes
preparing the dendrimer by the steps of: (1) forming the double
Michael addition product of acrylonitrile or methyacrylonitrile
with a primary polyamine; (2) hydrogenating the double Michael
addition product from step (1) to form primary polyamine
functionality; and (3) optionally, repeating steps (1) and (2)
using the product from step (2) to obtain higher generations of
dendrimers.
[0013] The primary polyamine in the initial step (1) is preferably
a diamine, such as, for example, 1,2-diaminoethane,
1,3-diaminopropane, 1,4-diaminobutane or the like.
[0014] The invention also includes terminally monomaleated
polyisobutylene essentially free of unmaleated polyisobutylene,
preferably less than 10 percent by weight of the
polyisobutylene.
[0015] The invention also embraces the star-branched polymeric
material prepared by the method described above which is
essentially free of unreacted polyisobutylene. By using a mixture
of two or more polyisobutylenes of different molecular weights the
branches on each dendrimer core can have mixed lengths.
[0016] Moreover, the present invention includes star branched
polymeric material comprising a hydrophilic dendrimer core with
mixed branches of functionalized polyolefin and the polyisoolefin.
The polyolefin branches can be a polymer or copolymer of ethylene,
propylene, butylene or the like. Preferably, the polyisoolefin is
polyisobutylene.
[0017] Moreover, the present invention includes star branched
polymeric material comprising a hydrolytically stable dendrimer
core with branches of polyolefins such as polyethylene,
polypropylene, ethylene-propylene copolymers, and the like. The
polyolefin is preferably polypropylene made with a metallocene
catalyst.
[0018] The present invention also provides a composition comprising
a blend of polyolefin, such as polyethylene, polypropylene,
ethylene-propylene copolymers and the like, with a star-branched
polymer comprising a dendrimer core and polyisoolefin branches or
the mixed branches. The polyolefin is preferably polypropylene,
more preferably polypropylene made with a metallocene catalyst. The
blend has particular utility in films with improved tear and
puncture resistance and controlled moisture/oxygen
permeability.
DESCRIPTION OF THE INVENTION
[0019] One aspect of the invention comprises a method for preparing
polyisoolefin such as polyisobutylene which has a reactive `exo`
terminal double bond chain end, and is essentially free of the
non-reactive `endo` terminal double bond chain end. The method has
particular advantage in functionalizing polyisobutylene to form
substantially exclusive `exo` reactive unsaturated groups, and to
use hydrocarbon solvents for the functionalization reactions.
Accordingly, polyisobutylene is referred to below for illustrative
purposes only and as a preferred embodiment.
[0020] Halogen-terminated polyisoolefins are conventionally
prepared by carbocationically polymerizing isoolefins having from 4
to about 12 carbon atoms in the presence of a halogenating agent
according to techniques well known in the art. Briefly, the
isoolefin is polymerized using halogenating initiators such as
2,4,4-trimethylpentyl chloride with a Friedel-Crafts acid
co-initiator such as BCl.sub.3 or TiCl.sub.4 in appropriate
halohydrocarbon solvent such as methyl chloride, methylene chloride
or the like. More detailed isoolefin polymerization techniques for
obtaining a halogen-terminated polyisoolefin are described in
Feinberg et al., Polymer Preparation, vol. 17, p. 797 (1976);
Kennedy et al., Polymer Preparation, vol. 17, p. 194 (1976);
Kennedy et al., Journal of Polymer Science, vol. 15, p. 2801
(1977); and Kennedy et al., Journal of Polymer Science, Polymer
Chemistry Edition, vol. 18, p. 1523 (1980) which are incorporated
herein by reference.
[0021] The polyisobutylene can be monohalogenated, but
di-halogenated or telechelic polyisobutylene is also known for
example, from U.S. Pat. No. 4,316,973 to Kennedy which is
incorporated herein by reference.
[0022] In accordance with this invention, dehydrohalogenation of
the halogen-terminated polyisobutylene is conducted in the presence
of a strong base represented by the formula RO-M wherein R
represents an alkyl group having at least 5 carbon atoms and M is
an alkali metal. The preferred base is potassium t-pentoxide, and
is referred to below for illustrative purposes only and as a
preferred embodiment.
[0023] The dehydrohalogenation reaction is preferably conducted in
an aliphatic solvent such as hexane, cyclohexane, heptane, octane
or the like. Solvents such as tetrahydrofuran (THF) are not
employed because of the potential for this solvent to form
peroxides and produce undesirable side reactions. The
dehydrohalogenation generally proceeds under reflux for a period of
time sufficient to substantially convert the halogen-terminated
polyisobutylene to vinylidene-terminated polyisobutylene (PIB-U),
typically a period of several hours. The reaction can be allowed to
cool to room temperature, washed with aqueous mineral acid to
remove potassium hydroxide, then with acetone/water, preferably in
a volume ratio of from 1:4 to 9:1, until neutral to remove
t-pentanol. The product can be dried with a hygroscopic material
such as CaCl.sub.2. Residual solvent can be evaporated, for
example, at elevated temperature under vacuum.
[0024] The weight average molecular weight of the PIB-U can range
from about 500 to about 500,000 and greater depending upon the
desired end use. For branches on a dendrimer core, the PIB
preferably has a molecular weight up to 50,000, more preferably
from 500 to 20,000.
[0025] According to the present invention the PIB-U is
functionalized for reactivity with amine. The PIB-U can have the
reactive terminal unsaturation converted, for example, to succinic
anhydride. Succinic anhydride groups are preferred, and thus
conversion of the PIB-U to succinic anhydride-terminated PIB
(PIB-SA) is preferred. PIB-SA is referred to below for illustrative
purposes only and as a preferred embodiment.
[0026] The PIB-U is converted to PIB-SA by heating a mixture of
PIB-U and maleic anhydride in approximately stoichiometric
proportions, typically with a slight excess of maleic anhydride,
generally to a temperature from 170.degree. to 250.degree. C.
[0027] This ene reaction can also be effected at elevated pressure
with or without a conventional ene catalyst.
[0028] The PIB-SA can be grafted to any dendrimer core having
primary amine-, terminated branches. A preferred dendrimer core is
the dendritic macromolecule described in U.S. Pat. No. 5,530,092
which is incorporated herein by reference in its entirety. Briefly,
the dendrimer core is prepared by reacting functional groups of a
primary diamine with acrylonitrile or methacrylonitrile, reducing
the incorporated nitrile groups to amine groups, and if desired,
reacting the amine groups with further acrylonitrile or
methacrylonitrile units in a reiterative fashion to prepare
succeeding generations in the branches emanating from the core.
[0029] As an example, 1,2-diaminoethane or 1,4 diaminobutane are
reacted with acrylonitrile or methacrylonitrile to form the
cyanide-terminated double Michael addition reaction product. This
product is then hydrogenated to obtain a first generation product
(G1) having 4 terminal amine groups. By reiterating the process,
second, third and fourth generation products (G2, G3, G4) can be
obtained which will respectively have 8, 16, and 32 terminal amine
groups and so on.
[0030] The PIB-SA is grafted onto the amine groups in the outer
shell of the dendrimer by condensation at elevated temperature to
form succinimide linkages, with or without a solvent. Preferably,
the PIB-SA and dendrimer are heated to the boiling point of the
solvent, such as toulene, for a sufficient length of time to obtain
a majority of succinimide linkages, but with some succinamic acid
linkages. This is preferably followed by evaporation of the solvent
and heating at 90.degree.-140.degree. C., preferably
110.degree.-120.degree. C., under high vacuum for a period of time
effective to effect complete ring closure, i.e. conversion of the
succinamic acid to succinimide.
[0031] The star-branched polymer comprising the dendrimer core and
the PIB branches via succinimide linkages has a number of uses,
including, for example, a viscosity modifier in organic liquid, as
a pour point depressant in diesel fuel, as a motor oil additive, as
a rheology modifier or processing aid in thermoplastic
compositions, as an adhesion promoter between polar and nonpolar
surfaces (especially by leaving some unreacted terminal amine
groups in the dendrimer core by using substoichrometric amounts of
the PIB), and the like. Since the star-branched polymer is
generally free of unreacted PIB, it has a greater effectiveness per
mass unit and less likely to have adverse effects otherwise due to
the presence of substantial amounts of unreacted PIB.
[0032] Using mixed-molecular weight PIB results in branches of
varying lengths. Using a mixture of hydrolytically stable dendrimer
cores results in varying core sizes and a varying number of
branches, e.g. G1 with G2 and/or G3 dendrimers. Furthermore, by
substituting some or all of the PIB branches with polyethylene,
polypropylene or ethylene-propylene copolymer branches, for
example, the properties of the star-branched polymer can be further
altered to tailor the star-branched polymer for use in a wider
range of systems, e.g. as a processing aid in polyethylene,
polypropylene and/or ethylene-polypropylene copolymer compositions.
Mixed-branch star polymers are prepared, for example, by reacting
the dendrimer core with a mixture of PIB-SA and maleated
polyethylene, polypropylene and/or ethylene-polypropylene
copolymer. The star branched polymer can also comprise the
hydrolytically stable dendrimer core and branches of
polyolefins.
[0033] The star-branched polymer is particularly effective in
blends with polyolefins as a means of controlling the transmission
of moisture and gases through films made from the blends. The
polyolefin can be polyethylene, polypropylene,
ethylene-polypropylene copolymer, polyisobutylene or the like. In a
preferred embodiment the star-branched polymer is used in a blend
with polypropylene made with a metallocene catalyst. The blend can
contain up to about 20 parts by weight of the star-branched
polymer, preferably 1 to 5 parts by weight, per 100 parts by weight
of the polypropylene. The type and amount of star-branched polymer
in the blend can be adjusted to obtain the desired balance between
physical properties on the one hand, and moisture and oxygen
permeability on the other. Generally, the use of a higher
generation star-branched polymer (e.g. PIB-G2 versus PIB-G1)
introduces more of the hydrophilic core material into the blend and
increases moisture/gas permeability. The polypropylene blends have
markedly enhanced large strain energy absorbing properties which
are important in tear and puncture resistance. The blends also have
high elongation properties suitable for polypropylene fiber
applications.
[0034] The blends can be prepared by solution or melt mixing using
conventional equipment. Melt mixing can be achieved by adding the
star-branched polymer to the polypropylene in the final
pellitization/granulation extrusion. Post-granulation blending can
also be done on conventional melt mixing equipment such as a
Banbury or Brabender mixer. The polypropylene is preferably melted
prior to addition of the star-branched polymer. The blends are
formed into films or fibers using conventional equipment and
techniques.
Example 1
Preparation of Exclusive `exo` Double Bonded
[0035] Monochlorine-terminated polyisobutylene (PIB-Cl) was
modified to obtain terminal succinic anhydride groups (PIB-SA). The
PIB-Cl had Mn of 5000 and Mw of 6050. 100% chlorine-terminated
polymer was confirmed by .sup.1H NMR. The PIB-Cl (.sup.28.5g) was
placed in a reaction flask with 200 ml of 0.35 molar potassium
t-pentoxide (t-PeOK) in cyclohexane and refluxed under nitrogen for
36 hours. The reaction product was washed with 10% HCl, water and
acetone/water (9:1) until neutral, dried under CaCl.sub.2, filtered
and dried under vacuum at 90.degree. C. for 2 days. Yield was 25g.
.sup.1H MNR at 300 MHZ showed a quantitative 100% conversion to
external unsaturated terminal groups (PIB-U).
EXAMPLE 2
[0036] Three grams of PIB-Cl was dissolved in 20 ml dry heptane.
The solution was clear. Twenty milliliters of potassium t-pentoxide
was added. The solution was still clear and contained only one
phase, indicating miscibility. The solution was refluxed for 30
hours in a 110.degree. C. bath under a nitrogen atmosphere. The
product was washed with water once and five times with 20%
acetone-water (20/80). The water wash was neutral. The organic
layer was distilled off and vacuum dried at 130.degree. C. for 6
hours. The viscous liquid was dried under vacuum at 65.degree. to
70.degree. C. for 2 days. The recovered polymer (2.8g) was analyzed
by .sup.1H NMR and had peaks at 1.75 ppm, 1.95 ppm and 4.65-4.85
ppm indicative of CH.sub.2--C(CH.sub.3).dbd.CH.sub.2 terminal
groups. There was no peak at 5.15 ppm, indicating an absence of the
undesirable `endo` double bond, --CH.dbd.C(CH.sub.3).sub.2.
Comparative Example 1
[0037] The reaction of PIB-Cl with the alkoxide of Example 3 is
repeated as above using potassium t-butoxide instead of potassium
t-pentoxide. No reaction occurs when the solvent is cyclohexane,
heptane or hexane.
Comparative Example 2
Preparation of PIB Containing Both `exo` and `endo` Double Bonds
Synthesized in Single Step
[0038] In this example, two PIB-U's were prepared. PIB-U1 of Mn
1000; PIB-U2 of Mn 2300 are prepared by carbocationic
polymerization of isobutylene using BF.sub.3-OEt.sub.2 catalyst,
which yield 85% `exo` and 15% `endo` unsaturation, in both
cases.
EXAMPLE 3
Preparation of PIB-SA
[0039] The PIB-U of Example 1 (22.5 g) and 5 g of maleic anhydride
were placed in a 2-neck flask swept with nitrogen. The flask was
heated to 190.degree.-200.degree. C. in a heating mantle with a
magnetic stirrer under nitrogen atmosphere for 36 hours, and cooled
to room temperature. Dry cyclohexane (200 ml) was added, heated
with stirring for 30 minutes, and then filtered. The filtrate was
evaporated to about 70 ml, and 300 ml acetone was added while
stirring. The mixture was warmed to 45.degree.-50.degree. C. while
stirring for 30 minutes, cooled to room temperature and acetone was
decanted off. This acetone wash procedure was repeated twice. The
polymer was dried under vacuum at about 90.degree. C. for one day.
A slightly brown clear liquid (PIB-SA) was obtained (20 g). FTIR
confirmed anhydride and .sup.1H NMR indicated quantitative
conversion to PIB-SA.
Comparative Example 3
Preparation of Partial PIB-SA
[0040] PIB-U1/2 prepared in Comparative Example 2 (1 mole
equivalent of double bond) and maleic anhydride (MA) (6 mole
equivalents of double bond) were placed in a flask filled with
argon. The flask was fitted with a condenser, and an argon bubbler
at the top. The flask was heated to 190.degree.-200.degree. C. in a
metal bath, and the reaction was continued at that temperature
while stirring with a magnetic stirrer under argon atmosphere. At
this temperature, the viscosity of the mixture (PIB-U1/2 and melted
MA) is low, and the magnetic stirrer is efficient for mixing. The
reaction was continued for 21 hours, cooled, dissolved in dry
hexane (15 gm/100 ml), and filtered to remove unreacted MA. Hexane
was evaporated out. The brown viscous mass was stirred with dry
acetone (20 gm/100ml) at 40.degree.-45.degree. C. for 30 mins,
allowed to cool, and acetone was decanted off. This was repeated
twice to be sure to remove any traces of unreacted MA. The light
brown viscous product was then dried under vacuum at 90.degree.
C.-100.degree. C. About 85% of `exo` structure was converted to the
corresponding anhydride terminal group. Thus, the products were a
mixture of PIB-SA which contained PIB-SA (63%), and unreacted
PIB-`exo` double bond (22%) and PIB-`endo` double bond (15%) as
confirmed from FTIR.
EXAMPLE 4
Preparation of Star Branched Polymer
[0041] The PIB-SA of Example 3 was reacted with dendrimer (G1)
obtained from DSM to prepare a star-branched polymer. Ten grams of
the PIB-SA was dissolved in 90 ml toluene (dried over molecular
sieve) in a 2-neck flask fitted with a gas bubbler. The solution
was clear. Then 0.145 g of the G1 dendrimer was dissolved in 5 ml
toluene in a vial and transferred to the 2-neck flask. The vial was
rinsed with an additional 5 ml toluene which was also transferred
to the 2-neck flask. The solution was gently refluxed overnight
while stirring under a nitrogen atmosphere. FTIR of the solution
indicated formation of free acid (--COOH) and amide (--CONH--). The
toluene was distilled off to obtain a light brown viscous product.
The product was heated to 110.degree.-120.degree. C. under high
vacuum for one day to complete the ring closure reaction, i.e.
conversion of succinamic acid to succinimide. FTIR analysis
indicated quantitative succinimide derivitization of the dendrimer
and was supported by .sup.1H NMR.
EXAMPLE 5
Preparation of Star Branched Polymer
[0042] The PIB-SA (6 g) of Example 3 was dissolved in 60 ml dry
toluene, and 0.12 g of G2 dendrimer obtained from DSM was added.
The solution was refluxed for 16 hours under a nitrogen atmosphere.
The solvent was distilled off. FTIR analysis indicated complete
amine-anhydride reaction with a majority of ring closure with some
succinamic acid. The product was dissolved in 60 ml cyclohexane,
washed twice with water and the cyclohexane was distilled off. The
slight brown product was washed twice with hot 60 ml acetone. The
product was transferred to a vial and heated to
110.degree.-120.degree. C. under high vacuum for 24 hours to effect
complete ring closure by conversion of succinamic acid to
succinimide. The oven was cooled to room temperature and filled
with nitrogen to take out the samples. The product was a slightly
brown viscous liquid.
EXAMPLES 6-11
[0043] A series of blends were made with two types of isotactic
polypropylene 5 and the star branched polymer PIB-G1 of Example 4.
The polypropylenes were prepared with a metallocene catalyst
(M-iPP) and Ziegler-Natta catalyst (ZN-iPP). Typically, that weight
average molecular weight, Mw, of such commercial isotactic
polypropylene polymers are in the range of 100,000 to 300,000. The
polypropylene and PIB-G1 were dissolved in hot xylene (about
130.degree. C.), precipitated in isopropanol and subsequently dried
under vacuum for 24 hours at about 80.degree. C. Thin pads were
made by molding for testing. The specimens were tested in
accordance with standard ASTM D-432 procedures (Instron cross head
speed 0.5 in./min; room temperature; notched specimen). The blend
compositions and testing data (average of four tests) are shown in
Table 1.
1TABLE 1 Composition and Physical Properties of PP/PIB-G1 Example 6
7 8 9 10 11 Composition (Parts by Weight) M-iPP 100 98 95 0 0 0
ZN-iPP 0 0 0 100 98 95 PIB-G1 0 2 5 0 2 5 Notched Tensile Test (RT
@ 0.5 in./min; average of 4) Modulus (1000 247 246 230 213 249 231
psi) Tensile 4.20 4.14 4.00 3.75 4.26 3.99 Strength (1000 psi)
Elongation (%) 11.9 18.3 25.4 31.7 22.2 15.9 Yield Strain 4.20 4.14
4.00 3.75 4.26 3.99 (1000 psi) Yield 4.5 4.6 4.7 4.7 4.7 4.5
Elongation (%) Energy/ 114 164 196 273 210 146 Thickness
(lbs-in./in.)
[0044] These data show that the M-iPP blends have enhanced energy
absorption without significant loss in inherent strength.
EXAMPLES 12 & 13
[0045] Preparation and performance of star branched dendrimer of a
functionalized polyolefin (maleic anhydride grafted polypropylene,
ma-PP) and a third generation (G-3) dendrimers.
[0046] In a laboratory scale Brabender mixer, 100 gm of Ma-PP
polymer was added and fluxed for about 10 minutes at 200 .degree.
C. After completely molten about 0.25 gm of hydrolytically stable
G-3 dendrimer was added. The mixture was allowed to mix for about 5
minutes to ensure homogeneity. During mixing, small amounts of
anti-oxidants (irganox 1010-Ciba Geigy) was added to avoid PP
degradation. Subsequently, the reacted material was compression
molded using a lab Carver press to obtain specimen for various
tests.
[0047] The Ma-PP used in the experiment was an Exxon Chemical
product sold under the Trade name Exxelor. Its MFR was 54 as
determined by the standard ASTM test. The Mw and MWD of Ma-PP were
about 110,000 and 2.3, respectively, as determined by GPC. The G-3
dendrimer used is made by DSM Netherlands. Its molecular weight is
reported to be 1684 g/mole. Its chemical nomenclature is DAB(PA)16-
16 cascade: 1,4 diamino butane[4]: (1-azabuitylidene) 12:
propylamine.
[0048] Physical properties of the parent Ma-PP are compared (Table
2) with that of its reaction product with G-3 dendrimer. It can be
readily noted that grafting of G-3 dendrimer had significantly
enhance the physical performance of the Ma-PP parent polymers. It
is specifically noted that MFR of the blend has been dramatically
reduced. The later indicates a grafting reaction of PP chains with
each other through G-3 dendrimer.
2 TABLE 2 Composition (Ma-PP to G- Maximum 3) parts by MFR
230.degree. C.; Modulus .times. Yield Stress, Displacement, weight
2, 16 10.sup.3, Pa Psi in Example 12- 100 54 153.5 3250 0.425
Control Example 13- 100 + 0.25 27 171 2855 0.371 Invention
* * * * *