U.S. patent application number 09/819119 was filed with the patent office on 2001-09-27 for opto-electronic devices fabricated with dual purpose electroactive copolymers.
Invention is credited to Hawker, Craig Jon, Klaerner, Gerrit, Lee, Jeong-Ik, Lee, Victor Yee-Way, Miller, Robert Dennis, Scott, John Campbell.
Application Number | 20010024738 09/819119 |
Document ID | / |
Family ID | 23217666 |
Filed Date | 2001-09-27 |
United States Patent
Application |
20010024738 |
Kind Code |
A1 |
Hawker, Craig Jon ; et
al. |
September 27, 2001 |
Opto-electronic devices fabricated with dual purpose electroactive
copolymers
Abstract
Multifunctional electroactive copolymers are provided. The
copolymers may be A-B-A triblock copolymers, brush-type graft
copolymers, or variations thereof. In a preferred embodiment, the
copolymers are "dual use" in that they comprise both a light
emitting segment and a charge transport segment. Methods of
synthesizing the novel electroactive copolymers are provided as
well, as are opto-electronic devices, particularly LEDs, fabricated
with the novel copolymers.
Inventors: |
Hawker, Craig Jon; (Los
Gatos, CA) ; Klaerner, Gerrit; (San Jose, CA)
; Lee, Jeong-Ik; (Kwonsun-gu, KR) ; Lee, Victor
Yee-Way; (San Jose, CA) ; Miller, Robert Dennis;
(San Jose, CA) ; Scott, John Campbell; (Los Gots,
CA) |
Correspondence
Address: |
REED & ASSOCIATES
800 MENLO AVENUE
SUITE 210
MENLO PARK
CA
94025
US
|
Family ID: |
23217666 |
Appl. No.: |
09/819119 |
Filed: |
March 27, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09819119 |
Mar 27, 2001 |
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09313903 |
May 18, 1999 |
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Current U.S.
Class: |
428/690 ;
313/504; 428/691; 428/917 |
Current CPC
Class: |
C08G 61/02 20130101;
C08G 73/0633 20130101; H01L 51/004 20130101; C08G 73/0694 20130101;
C08G 73/06 20130101; C08G 73/0688 20130101; H01L 51/0039 20130101;
C09K 11/06 20130101; H01L 51/5012 20130101; C08G 61/12 20130101;
C08G 73/02 20130101; H01L 51/0052 20130101; C08G 73/08 20130101;
H01L 51/0043 20130101; C08G 73/0627 20130101 |
Class at
Publication: |
428/690 ;
428/691; 428/917; 313/504 |
International
Class: |
H05B 033/12 |
Claims
1. A dual purpose electroactive copolymer comprising a charge
transporting polymeric segment and a light emitting polymeric
segment.
2. The dual purpose electroactive copolymer of claim 1, comprising
two or more charge transporting polymeric segments.
3. The dual purpose electroactive copolymer of claim 2, comprising
an A-B-A block copolymer in which each A represents a charge
transporting polymeric segment and B represents the light emitting
polymeric segment.
4. The dual purpose electroactive copolymer of claim 2, comprising
a brush-type graft copolymer having a backbone and pendant chains
covalently bound thereto.
5. The dual purpose electroactive copolymer of claim 4, wherein the
light emitting polymeric segment represents the backbone of the
copolymer, and the charge transporting polymeric segments represent
the pendant chains covalently bound thereto.
6. The dual purpose electroactive copolymer of claim 3, wherein the
charge transporting polymeric segments are comprised of arylamine
monomer units.
7. The dual purpose electroactive copolymer of claim 5, wherein the
charge transporting polymeric segments are comprised of arylamine
monomer units.
8. The dual purpose electroactive copolymer of claim 3, wherein the
charge transporting polymeric segments are comprised of conjugated
electron-deficient monomer units.
9. The dual purpose electroactive copolymer of claim 5, wherein the
charge transporting polymeric segments are comprised of
electron-deficient or electron-rich monomer units.
10. The dual purpose electroactive copolymer of claim 8, wherein
the monomer units are selected from the group consisting of aryl
sulfones, aryl sulfoxides, fluorinated aryls, biphenyls, diaryl
phosphine oxides, benzophenones, 1,2,3-triazole, 1,2,4-triazole,
1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole,
1,3,4-oxadiazole, 3,5-diaryl-1,2,4-oxadiazole,
3,4-diaryl-1,2,5-oxadiazole, 2,5-diaryl-1,3,4-oxadiazole,
1,4-oxazine, 1,2,5-oxathiazine, benzothiophene, 2,5-diaryl
oxadiazoles, thiophene, benzothiophene, pyridines, quinolines,
quinoxalines, and pyrimidines.
11. The dual purpose electroactive copolymer of claim 10, wherein
the monomer units comprise substituted ethylene units
--CH.sub.2--CHR-- in which R is selected from the group consisting
of aryl sulfones, aryl sulfoxides, fluorinated aryls, biphenyls,
diaryl phosphine oxides, benzophenones, 1,2,3-triazole,
1,2,4-triazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole,
1,2,5-oxadiazole, 1,3,4-oxadiazole, 3,5-diaryl-1,2,4-oxadiazole,
3,4-diaryl-1,2,5-oxadiazole, 2,5-diaryl-1,3,4-oxadiazole,
1,4-oxazine, 1,2,5-oxathiazine, 2,5-diaryl oxadiazoles, pyridines,
quinolines, quinoxalines, and pyrimidines.
12. The dual purpose electroactive copolymer of claim 3, wherein
the light emitting polymer segment is comprised of polycyclic
aromatic monomer units.
13. The dual purpose electroactive copolymer of claim 5, wherein
the light emitting polymer segment is comprised of polycyclic
aromatic monomer units.
14. The dual purpose electroactive copolymer of claim 12, wherein
the polycyclic aromatic monomer units are fluorescent.
15. The dual purpose electroactive copolymer of claim 13 wherein
the polycyclic aromatic monomer units are fluorescent.
16. The dual purpose electroactive copolymer of claim 14, wherein
the polycyclic aromatic monomer units comprise fluorene or a
derivative thereof.
17. The dual purpose electroactive copolymer of claim 15, wherein
the polycyclic aromatic monomer units comprise fluorene or a
derivative thereof.
18. The dual purpose electroactive copolymer of claim 16, wherein
the polycyclic aromatic monomer units each comprise a
9,9-dialkylfluorene moiety, and further wherein each such moiety is
bound through its 2-position to a first adjacent monomer unit and
through its 7-position to a second adjacent monomer unit.
19. The dual purpose electroactive copolymer of claim 17, wherein
the polycyclic aromatic monomer units each comprise a fluorene
moiety, wherein at least some of the moieties are bound through
their 9-position to one or two of the pendant chains.
20. A process for preparing a dual purpose electroactive copolymer
comprised of charge transport polymeric segments and a light
emitting polymeric segment, which comprises: (a) contacting a
dihalo-substituted polycyclic aromatic reactant with a living free
radical polymerization initiator under conditions effective to
bring about polymerization, resulting in a light emitting polymeric
intermediate comprised of linked polycyclic aromatic monomer units
and two or more displaceable termini; and (b) synthesizing a charge
transport polymeric segment comprised of polymerized charge
transporting monomer units at each of the displaceable termini, via
living free radical polymerization.
21. The process of claim 20, wherein the polymeric intermediate
contains two displaceable termini, and the dual purpose
electroactive copolymer is an A-B-A block copolymer in which each A
represents a charge transporting polymeric segment and B represents
the light emitting polymeric segment.
22. The process of claim 20, wherein the polymeric intermediate
contains more than two displaceable termini, and the dual purpose
electroactive copolymer is a brush-type graft copolymer having a
backbone and pendant chains covalently bound thereto.
23. The process of claim 22, wherein the light emitting polymeric
segment represents the backbone of the copolymer, and the charge
transporting polymeric segments represent the pendant chains
covalently bound thereto.
24. The process of claim 21, wherein the charge transporting
polymeric segment is comprised of arylamine monomer units.
25. The process of claim 23, wherein the charge transporting
polymeric segment is comprised of arylamine monomer units.
26. The process of claim 21, wherein the aromatic monomer units in
the light-emitting polymeric segment are electron-deficient or
electron-rich.
27. The process of claim 23, wherein the aromatic monomer units in
the light-emitting polymeric segment are electron-deficient or
electron-rich.
28. The process of claim 26, wherein the electron-deficient or
electron-rich monomer units are selected from the group consisting
of aryl sulfones, aryl sulfoxides, fluorinated aryls, biphenyls,
diaryl phosphine oxides, benzophenones, 1,2,3-triazole,
1,2,4-triazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole,
1,2,5-oxadiazole, 1,3,4-oxadiazole, 3,5-diaryl-1,2,4-oxadiazole,
3,4-diaryl-1,2,5-oxadiazole, 2,5-diaryl-1,3,4-oxadiazole,
1,4-oxazine, 1,2,5-oxathiazine, 2,5-diaryl oxadiazoles, pyridines,
quinolines, quinoxalines, and pyrimidines.
29. The process of claim 27, wherein the electron-deficient or
electron-rich monomer units are selected from the group consisting
of aryl sulfones, aryl sulfoxides, fluorinated aryls, biphenyls,
diaryl phosphine oxides, benzophenones, 1,2,3-triazole,
1,2,4-triazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole,
1,2,5-oxadiazole, 1,3,4-oxadiazole, 3,5-diaryl- 1,2,4-oxadiazole,
3,4-diaryl- 1,2,5-oxadiazole, 2,5-diaryl-1,3,4-oxadiazole,
1,4-oxazine, 1,2,5-oxathiazine, benzothiophene, 2,5-diaryl
oxadiazoles, thiophene, benzothiophene, pyridines, quinolines,
quinoxalines, and pyrimidines.
30. The process of claim 21, wherein the polycyclic aromatic
monomer units are fluorescent.
31. The process of claim 23, wherein the polycyclic aromatic
monomer units are fluorescent.
32. The process of claim 30, wherein the polycyclic aromatic
monomer units comprise fluorene or a derivative thereof.
33. The process of claim 31, wherein the polycyclic aromatic
monomer units comprise fluorene or a derivative thereof.
34. The process of claim 21, wherein the polycyclic aromatic
monomer units each comprise a 9,9-dialkylfluorene moiety, and
further wherein, following step (a), each such moiety is bound
through its 2-position to a first adjacent monomer unit and through
its 7-position to a second adjacent monomer unit.
35. The process of claim 23, wherein the polycyclic aromatic
monomer units each comprise a fluorene moiety, and further wherein,
following step (a), at least some of the moieties are bound through
their 9-position to one or two of the pendant chains.
36. The process of claim 20, wherein step (a) is conducted
catalytically using a metal catalyst.
37. The process of claim 36, wherein the metal catalyst is nickel
or a salt or complex thereof.
38. The process of claim 37, wherein the metal catalyst is
bis(1,5-cyclooctadiene) nickel (0).
39. The process of claim 20, wherein step (a) is conducted in the
presence of a living free radical polymerization initiator.
40. The process of claim 39, wherein the living free radical
polymerization initiator comprises a TEMPO-containing
monoarylhalide.
41. The process of claim 40, wherein the living free radical
polymerization initiator comprises
1-((4-bromophenyl)ethoxy)-2,2,6,6-tetr- amethylpiperidine.
42. A process for preparing a dual purpose electroactive copolymer
comprised of charge transport polymeric segments and a light
emitting polymeric segment, which comprises: (a) contacting a
unimolecular living free radical polymerization initiator with a
polymerizable reactant under polymerization conditions, wherein the
initiator, the reactant, and the polymerization conditions are
effective to provide a charge transporting polymeric intermediate
comprised of a plurality of linked monomer units and a single
reactive terminus; and (b) catalytically polymerizing a
dihalo-substituted polycyclic aromatic reactant in the presence of
the charge transporting polymeric intermediate, whereby a light
emitting polymeric segment comprised of linked polycyclic aromatic
monomer units is formed, with two or more charge transporting
polymeric segments bound thereto.
43. In an opto-electronic device comprising a substrate provided
with an electroactive polymeric material on the surface thereof,
the improvement comprising employing as the electroactive polymeric
material the dual purpose electroactive copolymer of claim 1.
44. In an opto-electronic device comprising a substrate provided
with an electroactive polymeric material on the surface thereof,
the improvement comprising employing as the electroactive polymeric
material the dual purpose electroactive copolymer of claim 3.
45. In an opto-electronic device comprising a substrate provided
with an electroactive polymeric material on the surface thereof,
the improvement comprising employing as the electroactive polymeric
material the dual purpose electroactive copolymer of claim 5.
46. The opto-electronic device of claim 43, comprising a
light-emitting diode.
47. The opto-electronic device of claim 44, comprising a
light-emitting diode.
48. The opto-electronic device of claim 45, comprising a
light-emitting diode.
Description
TECHNICAL FIELD
[0001] This invention relates generally to electroactive polymers.
More particularly, the invention pertains to dual purpose
electroactive copolymers, preparation thereof, and use in the
manufacture of various types of opto-electronic devices.
BACKGROUND
[0002] Electroactive polymers are frequently used in a number of
optical and electronic applications such as in light emitting
diodes ("LEDs"), photovoltaic energy converters, photodetectors,
photoconductors, e.g., in electrophotography, and in chemical and
biochemical sensors. In each of these applications, it is often
necessary to use a multiplicity of electroactive polymeric
materials each having a different function in the device. For
example, different polymeric materials are normally used to provide
electron and/or hole charge transport, luminescence, photo-induced
charge generation, and charge blocking or storage. By working with
a number of structurally and functionally distinct polymers, one
can achieve optimization of these separate functions.
[0003] It would be desirable, however, to reduce the number of
polymeric materials needed in any particular opto-electronic
device. In this way, the manufacture of opto-electronic devices is
simplified by reducing the time, cost and number of materials
involved in device fabrication.
[0004] The present invention is addressed to the aforementioned
need in the art. A new class of electroactive polymers is now
provided, comprising copolymers in which discrete and functionally
unique segments present in a single polymer render the polymer
multifunctional in nature. In a preferred embodiment, the
electroactive copolymers are "dual use" polymers by virtue of
containing both a charge transport segment and a light emissive
segment. The invention represents an important advance in the art,
insofar as the number of polymeric materials previously required in
the manufacture of opto-electronic devices may now be significantly
reduced. That is, with the present invention, fewer discrete and
functionally unique polymeric layers are now necessary to provide
all of the desired functions, e.g., electron transport, hole
transport, light emission, and the like.
SUMMARY OF THE INVENTION
[0005] Accordingly, it is a primary object of the invention to
address the above-mentioned need in the art by providing a dual
purpose electroactive copolymer useful in the manufacture of an
opto-electronic device.
[0006] It is another object of the invention to provide such a
copolymer which comprises a charge transporting polymeric segment
and a light emitting polymeric segment.
[0007] It is still another object of the invention to provide such
a copolymer in the form of an A-B-A triblock copolymer.
[0008] It is yet another object of the invention to provide such a
copolymer in the form of a brush-type graft copolymer.
[0009] It is an additional object of the invention to provide
methods for synthesizing dual use electroactive polymers as
disclosed and claimed herein.
[0010] It is still an additional object of the invention to provide
opto-electronic devices, particularly LEDs, fabricated with a dual
use electroactive copolymer as disclosed and claimed herein.
[0011] Additional objects, advantages and novel features of the
invention will be set forth in part in the description which
follows, and in part will become apparent to those skilled in the
art upon examination of the following, or may be learned by
practice of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 schematically illustrates preparation of an end
capping initiator and two macromolecular end capping reagents, as
described in Examples 1, 2 and 3, respectively.
[0013] FIG. 2 schematically illustrates preparation of a
macromolecular end capping reagent and a macromolecular initiator,
as described in Examples 4 and 5, respectively.
[0014] FIG. 3 schematically illustrates macromolecular initiation
reactions as described in Examples 6 and 7.
[0015] FIG. 4 schematically illustrates the macromolecular end
capping reaction described in Example 8, part (a).
[0016] FIG. 5 schematically illustrates the macromolecular end
capping reaction described in Example 8, part (b).
[0017] FIG. 6 schematically illustrates preparation of a radical
initiating condensation monomer, as described in Example 9, parts
(a) and (b).
[0018] FIG. 7 schematically illustrates preparation of polystyrene
grafted on "Br2BTFLUO" as described in Example 9, part (c).
[0019] FIG. 8 schematically illustrates the Yamamoto polymerization
reaction described in Example 9, part (d).
[0020] FIG. 9 schematically illustrates the macromolecular
initiated radical polymerization reaction described in Example 9,
part (e).
[0021] FIG. 10 is a cross-sectional view of an embodiment of a
light-emitting device as may be prepared using the electroactive
copolymers of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0022] Overview and Definitions
[0023] Before describing the present invention in detail, it is to
be understood that this invention, unless otherwise indicated, is
not limited to specific compositions, components or process steps,
as such may vary. It is also to be understood that the terminology
used herein is for the purpose of describing particular embodiments
only, and is not intended to be limiting.
[0024] It must be noted that, as used in this specification and the
appended claims, the singular forms "a," "an," and "the" include
plural referents unless the context clearly dictates otherwise.
Thus, for example, reference to "a polymeric segment" includes more
than one polymeric segment, reference to "a layer" or "a polymeric
layer" includes multiple layers, reference to "a reagent" includes
mixtures of reagents, and the like.
[0025] In describing and claiming the present invention, the
following terminology will be used in accordance with the
definitions set out below.
[0026] The term "polymer" is used to refer to a chemical compound
that comprises linked monomers, and that may or may not be linear.
The electroactive copolymers of the present invention generally
comprise at least about 20 monomer units, preferably at least about
50 monomer units, and generally fewer than about 200 monomer units,
preferably fewer than about 150 monomer units.
[0027] The term "electroactive" as used herein refers to a material
that is (1) capable of transporting, blocking or storing charge
(either+or-), (2) luminescent, typically although not necessarily
fluorescent, and/or (3) useful in photo-induced charge
generation.
[0028] The term "alkyl" as used herein refers to a branched or
unbranched saturated hydrocarbon group of 1 to 24 carbon atoms,
such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl,
t-butyl, octyl, decyl, tetradecyl, hexadecyl, eicosyl, tetracosyl
and the like, as well as cycloalkyl groups such as cyclopentyl,
cyclohexyl and the like. The term "lower alkyl" intends an alkyl
group of one to six carbon atoms, preferably one to four carbon
atoms.
[0029] The term "alkenyl" as used herein refers to a branched or
unbranched hydrocarbon group of 2 to 24 carbon atoms containing at
least one double bond, typically containing one to six double
bonds, more typically one or two double bonds, e.g., ethenyl,
n-propenyl, n-butenyl, octenyl, decenyl, and the like, as well as
cycloalkenyl groups such as cyclopentenyl, cyclohexenyl and the
like. The term "lower alkenyl" intends an alkenyl group of two to
six carbon atoms, preferably two to four carbon atoms.
[0030] The term "alkynyl" as used herein refers to a branched or
unbranched hydrocarbon group of 2 to 24 carbon atoms containing at
least one triple bond, e.g., ethynyl, n-propynyl, n-butynyl,
octynyl, decynyl, and the like, as well as cycloalkynyl groups such
as cyclooctynyl, cyclononynyl, and the like. The term "lower
alkynyl" intends an alkynyl group of two to six carbon atoms,
preferably two to four carbon atoms.
[0031] The term "alkoxy" as used herein refers to a substituent
--O--R wherein R is alkyl as defined above. The term "lower alkoxy"
refers to such a group wherein R is lower alkyl.
[0032] The terms "aryl" and "aromatic," as used herein, and unless
otherwise specified, refer to an aromatic moiety containing one to
seven aromatic rings. For aryl groups containing more than one
aromatic ring, the rings may be fused or linked. Aryl groups are
optionally substituted with one or more substituents per ring;
suitable substituents include, for example, halo, haloalkyl, alkyl,
alkenyl, alkynyl, alkoxy, alkoxycarbonyl, carboxy, nitro, cyano and
sulfonyl. The term "aryl"is also intended to include heteroaromatic
moieties, i.e., aromatic heterocycles. Generally the heteroatoms
will be nitrogen, oxygen or sulfur.
[0033] The term "arylene" as used herein, and unless otherwise
specified, refers to a bifunctional aromatic moiety containing two
to seven aromatic rings that are either fused or linked. Arylene
groups are optionally substituted with one or more substituents per
ring; as above, suitable substituents include halo, haloalkyl,
alkyl, alkenyl, alkynyl, alkoxy, alkoxycarbonyl, carboxy, nitro,
cyano and sulfonyl.
[0034] The term "halo" is used in its conventional sense to refer
to a chloro, bromo, fluoro or iodo substituent. In the compounds
described and claimed herein, halo substituents are generally
bromo, chloro or iodo, preferably bromo or chloro. The terms
"haloalkyl," "haloaryl" (or "halogenated alkyl" or "halogenated
aryl") refer to an alkyl or aryl group, respectively, in which at
least one of the hydrogen atoms in the group has been replaced with
a halogen atom.
[0035] "Optional" or "optionally" means that the subsequently
described circumstance may or may not occur, so that the
description includes instances where the circumstance occurs and
instances where it does not. For example, the phrase "optionally
substituted" means that a non-hydrogen substituent may or may not
be present, and, thus, the description includes structures wherein
a non-hydrogen substituent is present and structures wherein a
non-hydrogen substituent is not present.
[0036] The invention thus provides electroactive copolymers that
comprise both a charge transporting polymeric segment and a light
emitting polymeric segment. The presence of these discrete and
functionally unique segments in a single polymer molecule renders
the copolymer multifunctional in nature (i.e., "dual purpose" at a
minimum), insofar as the copolymer is both luminescent, i.e., light
emitting, and capable of transporting charge, either positive or
negative.
[0037] Triblock Copolymers
[0038] In one embodiment, the novel copolymers are A-B-A triblock
copolymers, in which one of A and B is a charge transporting
polymeric segment and the other is a light emitting polymeric
segment. Preferably, it is each A block that is a charge
transporting polymeric segment, while the B block is a light
emitting polymeric segment.
[0039] The monomer units present in the charge transporting
polymeric segment are selected to correspond to the intended use of
the polymer. When the charge transporting segment is to be hole
transporting, the monomer units in the segment are preferably
arylamines, e.g., triphenylamine, diphenyltolylamine,
tetraphenyl-p-phenylene diamine, tetraphenylbenzidine, an
arylamine-containing polynuclear aromatic and/or heteroaromatic
compound, or a diarylamine such as an N-substituted carbazole or an
aminobenzaldehyde hydrazone. When the charge transporting segment
is to be an electron transporting segment, i.e., when the copolymer
is used as an electron transport layer in an LED, photoconductor or
the like, the monomer units are preferably electron deficient
moieties that are "conjugated" in the polymer structure, and
include heterocyclic and/or nonheterocyclic aromatic groups, e.g.,
aryl sulfones (e.g., biphenyl sulfone), aryl sulfoxides,
fluorinated aryls (such as bis(diphenylhexafluoropropane) and
octafluorobiphenyl), biphenyls, diaryl phosphine oxides,
benzophenones, 1,2,3-triazole, 1,2,4-triazole, 1,2,3-oxadiazole,
1,2,4-oxadiazole (azoxime), 1,2,5-oxadiazole (furazan),
1,3,4-oxadiazole, 3,5-diaryl-1,2,4-oxadiazole- ,
3,4-diaryl-1,2,5-oxadiazole, 2,5-diaryl-1,3,4-oxadiazole,
1,4-oxazine, 1,2,5-oxathiazine, thiophene, benzothiophene,
pyridines, quinolines (including quinoline and isoquinoline),
quinoxalines, and pyrimidines.
[0040] The monomer units in the light emitting polymeric segment
are aromatic or heteroaromatic, and include polycyclic aromatic
moieties that are typically although not necessarily fluorescent.
These monomer units include without limitation benzene,
naphthalene, anthracene, phenanthrene, indene, pyrene, perylene,
phenalene, coronene, fluorescein, fluorene, substituted fluorene,
and the like. Exemplary monomers for forming the light emitting
polymeric segment are those that have previously been disclosed in
co-pending, commonly assigned U.S. patent application Ser. No.
08/888,172, filed Aug. 27, 1997, entitled "Polymeric Light-Emitting
Device," as useful for forming an emissive layer, e.g., in an LED.
Those monomers include: dihalo-fluorene optionally substituted with
one or more substituents other (i.e., non-halogen substituents)
such as phenyl, benzyl, phenoxy, benzyloxy, lower alkyl or lower
alkoxy, preferably at but not restricted to the 9-position, e.g.,
9,9-dialkylfluorene and 9,9-diphenylfluorene; and dihaloanthracene
optionally substituted with one or more of the aforementioned
substituents, e.g., 9,10-, 2,6-, 1,8- or 1,4-dihaloanthracene or
dihalodiphenylanthracenes. Aromatic dyes, e.g., coumarins,
rhodamines, pyrans, or the like may also serve as monomer units in
the light emitting polymeric segment, for example, to provide a
copolymer that can be used as a photoconductive sensitizer.
[0041] A-B-A triblock copolymers of the invention, wherein A is a
charge transporting polymeric segment and B is a light emissive
polymeric segment, may be synthesized using either of two
techniques. A first synthetic method comprises: (a) contacting a
dihalo-substituted polycyclic aromatic reactant with a haloaryl
moiety also containing a living free radical polymerization
initiator under conditions effective to bring about condensation
polymerization, resulting in a light emitting polymeric
intermediate comprised of linked polycyclic aromatic monomer units
and two or more displaceable termini; and (b) synthesizing, at each
of the termini of the intermediate prepared in step (a), a charge
transport segment comprised of polymerized monomer units. The
polymeric end-capping reagents prepared in step (b) are
preferentially synthesized via living free radical polymerization.
Part (a) of the method may be shown schematically as follows: 1
[0042] In the above scheme, compound (1) is the dihalo-substituted
polycyclic aromatic reactant, wherein Hal represents a halogen
atom, typically chloro or bromo, and X is an aromatic or
heteroaromatic moiety as explained earlier herein. That is, X is
generally although not necessarily fluorescent, and may be, for
example, benzene, naphthalene, anthracene, phenanthrene, indene,
pyrene, perylene, phenalene, coronene, fluorescein, fluorene,
substituted fluorene, and the like. In a preferred embodiment, X is
fluorene substituted with one or more substituents such as phenyl,
benzyl, phenoxy, benzyloxy, lower alkyl or lower alkoxy, preferably
but not necessarily at the 9-position, as in 9,9-dialkylfluorene
and 9,9-diphenylfluorene. Compound (II) is a living free radical
polymerization initiator, in which the free radical R.multidot. is
capable of end capping the polymerization of (I), and R.sup.1 and
R.sup.2 are each independently alkyl or aryl, including substituted
and unsubstituted alkyl and aryl, wherein the substituents are, for
example, cyano, carboxyl, and the like, or R.sup.1 and R.sup.2
together form an optionally alkyl-substituted cycloalkyl ring
containing 4 to 7, typically 5 or 6, carbon atoms. No hydrogen
atoms should be present on the carbon atoms adjacent to N in the
--NR.sup.1R.sup.2 group. Suitable R groups are alkyl, aryl,
aryl-substituted alkyl, although preferred R groups comprise
halogenated aryl moieties. Examples of specific R groups include
phenyl, substituted phenyl (particularly halogenated phenyl such as
p-bromophenyl and p-chlorophenyl), benzyl, substituted benzyl
(particularly halogenated benzyl), lower alkyl, particularly methyl
and tertiary butyl, and cyanoisopropyl. In general the structure of
R will be of the formula 2
[0043] wherein R', R" and R'" are the same or different and are
selected from the group consisting of hydrogen, alkyl, halogenated
alkyl, phenyl, halogenated phenyl, benzyl, and halogenated benzyl.
Suitable living free radical polymerization initiators are
derivatives of 2,2,6,6-tetramethyl- 1-piperidinyloxy ("TEMPO"),
having the structural formula 3
[0044] wherein R' is as defined above, and Q is halogen, preferably
chloro or bromo. The "TEMPO" moiety itself has the structural
formula 4
[0045] The polymeric intermediate (III) comprises a light emitting
polymeric segment represented by --[X].sub.n-- and having two
displaceable termini 5
[0046] deriving from the nitroxyl groups of the polymerization
initiator.
[0047] The reaction illustrated in Scheme 1 is preferably conducted
in the presence of a catalyst, preferably a nickel catalyst.
Exemplary nickel catalysts include ligand-substituted Ni (0)
complexes and ligand-substituted Ni (II) complexes that generate Ni
(0) in situ; it may be desirable to use a reducing agent such as Zn
with the latter class of catalysts. Particularly preferred nickel
catalysts include bis (1,5-cyclooctadiene) nickel (0) and nickel
carbonyl tris (triphenylphosphine) nickel (0).
[0048] Step (b) of the reaction, wherein polymer blocks are
synthesized at the termini of the intermediate (III), may be
represented schematically as follows: 6
[0049] Polymerization of the vinyl moiety (IV), i.e.,
CH.sub.2.dbd.CY.sup.1Y.sup.2, at the termini of intermediate (III)
results in two conjugated terminal blocks, each of which is bound
to the central segment, to provide the "A-B-A" triblock structure
(V). In this process, the nitroxyl-terminated intermediate (III)
serves as an initiator for the living free radical polymerization
of the vinyl monomer (IV). The molecular moieties Y.sup.1 and
Y.sup.2, which may be the same or different, are either
electron-deficient or electron-rich monomer units that provide a
vinyl polymer following initiation of polymerization, as discussed
above. That is, Y.sup.1 and Y.sup.2 are typically heterocyclic
and/or nonheterocyclic aromatic groups, e.g., aryl sulfones (e.g.,
biphenyl sulfone), aryl sulfoxides, fluorinated aryls (such as
bis(diphenylhexafluoropropane) and octafluorobiphenyl), biphenyl, a
diaryl phosphine oxide, a benzophenone, 1,2,3-triazole,
1,2,4-triazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole (azoxime),
1,2,5-oxadiazole (furazan), 1,3,4-oxadiazole,
3,5-diaryl-1,2,4-oxadiazole- , 3,4-diaryl-1,2,5-oxadiazole,
2,5-diaryl-1,3,4-oxadiazole, 1,4-oxazine, 1,2,5-oxathiazine,
benzothiophene, thiophene, pyridine, a quinoline (including
quinoline and isoquinoline), a quinoxaline, a pyrimidine, or the
like. When the charge transporting segment is to be hole
transporting, the monomer units in the segment are preferably
arylamines, e.g., triphenylamine, diphenyltolylamine,
tetraphenyl-p-phenylene diamine, tetraphenylbenzidine, an
arylamine-containing polynuclear aromatic and/or heteroaromatic
compound, or a diarylamine such as an N-substituted carbazole or an
aminobenzaldehyde hydrazone. In the triblock copolymer product (V),
m is typically in the range of approximately 10 to 200, preferably
10 to 100, while n is generally in the range of approximately 2 to
50, preferably 6 to 50.
[0050] An alternative synthetic route to these A-B-A triblock
copolymers involves (a) contacting a unimolecular living free
radical polymerization initiator with a polymerizable reactant
under polymerization conditions, wherein the initiator, the
reactant, and the polymerization conditions are effective to
provide a charge transporting polymeric intermediate comprised of a
plurality of linked monomer units and a single reactive terminus;
and (b) catalytically polymerizing a dihalo-substituted polycyclic
aromatic reactant in the presence of the charge transporting
polymeric intermediate, whereby a light emitting polymeric segment
comprised of linked polycyclic aromatic monomer units is formed,
with two or more charge transporting polymeric segments bound
thereto. This may be shown schematically as follows: 7
[0051] The unimolecular living free radical polymerization
initiator is shown at (IIA), wherein R.sup.1 and R.sup.2 are as
defined earlier herein and wherein R* is identical to R but
contains a reactive site that enables binding of an additional
moiety, as carried out in step (b). The polymerizable reactant is
shown at (IV), wherein Y.sup.1 and Y.sup.2 are as defined earlier
herein as well. The reaction forms a monofunctionalized polymeric
charge transporting block, i.e., the charge transporting polymeric
intermediate (VI), comprised of a plurality of linked monomer units
"--CH.sub.2--C(Y.sup.1Y.sup.2)--" and a single reactive termninus
R*. Step (b) may be represented as follows: 8
[0052] In step (b), the charge transporting polymeric intermediate
having the single reactive terminus, i.e., structure (VI), is
caused to react with a dihalo-substituted polycyclic aromatic
reactant (I), wherein Hal and X are as defined above, in the
presence of a suitable catalyst, preferably a nickel catalyst such
as bis (1,5-cyclooctadiene) nickel (0). The reaction results in a
triblock copolymer shown at (V) in which the central block is a
light emitting polymeric segment comprised of linked aromatic
monomer units, and the outer blocks are charge transporting
polymeric segment comprised of electron-deficient or electron-rich
monomeric moieties.
[0053] Brush-Type Graft Copolymers
[0054] In another embodiment, the novel copolymers are brush-type
graft copolymers. It will be appreciated by those skilled in the
art that "brush-type" graft copolymers are polymers comprised of a
backbone polymer chain to which are attached a plurality of pendant
polymer chains, with the attached (or "grafted") pendant polymer
chains chemically distinct from the backbone polymer chain. In the
brush-type copolymers of the invention, the backbone segment of the
copolymer has a first property and the pendant chains have other
properties. Preferably, the backbone is light emitting and the
pendant chains are charge transporting, or vice versa. The monomer
units in the charge transporting polymeric segments are as set
forth with respect to the A-B-A triblock copolymers described in
the preceding section. That is, when the charge transporting
segment is to be hole transporting, the monomer units are
preferably arylamines, while when the transporting segment is to be
electron transporting, the monomer units are conjugated aromatic
moieties, e.g., oxazines, oxathiazenes, thiophenes, oxadiazoles,
and the like. The monomer units in the light emitting polymeric
segment are also as set forth with regard to the A-B-A triblock
copolymers, i.e., they are polycyclic aromatic moieties that are
typically although not necessarily fluorescent. In this case,
however, a fraction of the aromatic monomers that are polymerized
to form the polymer backbone are provided with branch points that
enable synthesis of the pendant, "grafted" polymer chains. Thus,
for example, to prepare brush-type copolymers having a light
emitting backbone and charge transporting pendant chains, one would
carry out the reaction shown in Scheme 1 but add in polymerizable
monomers Hal--[Z]-- Hal wherein Z is identical to X but includes a
reactive site enabling branching. A specific example of such a
reaction is illustrated comprehensively in FIG. 3, wherein a first
monomer is a 9,9-alkyl-substituted fluorene and a second monomer is
a functionalized 9,9-di-substituted fluorene as shown, resulting in
a backbone containing both such monomers, wherein the
functionalized 9,9-di-substituted monomer units enable preparation
of additional polymeric segments at the 9-position of those
monomers in the polymer chain.
[0055] It will be appreciated by those skilled in the art that the
present methodology can be is used to prepare combinations of
copolymer types, e.g., brush-type polymers having pendant chains
that are branched, brush-type polymers containing copolymeric
pendant chains, A-B-A triblock copolymers in which the A blocks are
provided with pendant chains, and the like. Such modifications of
the basic polymers and processes disclosed herein are within the
scope of the present invention.
[0056] Opto-Electronic Devices
[0057] The devices that may be fabricated using the present
electroactive copolymers synthetic methods include LEDs,
photovoltaic cells, photoconductors, photodetectors, and chemical
and biochemical sensors. A primary application of the present
invention is in the fabrication of LEDs, semiconductor devices that
convert electrical energy into electromagnetic radiation and are
suitable for use as illumination sources, in displays and in
indicator lamps.
[0058] FIG. 10 illustrates an LED prepared using the composition
and method of the invention. A charge transporting and emissive
layer 2 comprises an electroactive copolymer of the invention and
is sandwiched between and contiguous with opaque electrode 4 and
transparent electrode . The device is supported on a glass base 8.
When a voltage is applied to electrodes 4 and 6, electrons and
holes are injected from opposite electrodes, and light is emitted
from layer 2 which then radiates from the device through
transparent electrode 6 and glass base 8. The electrodes 4 and 6
comprise a conductive material. Suitable opaque electrodes can
comprise gold, aluminum, copper, silver or alloys thereof. Suitable
transparent electrodes comprise, for example, indium tin oxide,
polyaniline or polythiophene.
[0059] Such a device is conveniently fabricated by dissolving a
dual use polymer as provided herein in a suitable solvent, e.g.,
p-xylene, toluene, or the like, and casting a film of the polymer
solution on one of the electrodes. The polymer film is then cured
using conventional means. Alternatively, the dual use polymer can
be synthesized on a substrate such as an electrode surface using
the synthetic processor discussed in detail herein. Subsequent
layers can be provided in a similar manner, if desired. In the
final fabrication step, the second electrode is formed or deposited
on the exposed cured surface.
[0060] It is to be understood that while the invention has been
described in conjunction with the preferred specific embodiments
thereof, that the foregoing description as well as the examples
which follow are intended to illustrate and not limit the scope of
the invention. Other aspects, advantages and modifications within
the scope of the invention will be apparent to those skilled in the
art to which the invention pertains.
[0061] All patents, patent applications, and publications mentioned
herein are hereby incorporated by reference in their
entireties.
EXPERIMENTAL
[0062] The following examples are put forth so as to provide those
of ordinary skill in the art with a complete disclosure and
description of how to prepare and use the oligomers and polymers
disclosed and claimed herein. Efforts have been made to ensure
accuracy with respect to numbers (e.g., quantities, temperature,
etc.) but some errors and deviations should be accounted for.
Unless indicated otherwise, parts are parts by weight, temperature
is in .degree. C. and pressure is at or near atmospheric.
Additionally, all starting materials were obtained commercially or
synthesized using known procedures.
[0063] Instrumentation
[0064] The synthesized compounds were identified by their .sup.1H
and .sup.13C-NMR spectra obtained on a Bruker AF 250 Spectrometer.
Melting points were determined using a Gallenkamp melting point
apparatus and are uncorrected. UV-visible and fluorescence spectra
were obtained with a Hewlett Packard 8452A diode array
spectrophotometer and an SA Instruments FL3-11 Fluorometer,
respectively. Thermogravimetric analysis (TGA) and Differential
Scanning Calorimeter (DSC) of the polymers were performed under a
nitrogen atmosphere at a heating rate of 10.degree. C./min with a
Perkin Elmer TGS-2 and a DuPont 2100 analyzer, respectively. A
Waters 150-C Gel Permeation Chromatograph was used to determine
molecular weights of the polymers which are based on poly(styrene)
standards.
Example 1
Synthesis Of An End-Capping Initiator
[0065] 1-(4'-bromophenyl)-1-(2",2", 6",
6"-tetramethyl-1-piperidinyloxy)et- hyl, 1 (FIG. 1): To a solution
of p-bromostyrene, (25.0 g, 137 mmol) and
2,2,6,6-tetramethylpiperidinyloxy (TEMPO) (21.3 g, 137 mmol) in 1:1
toluenelethanol (1000 mL) was added
[N,N'-bis(3,5-di-t-butylsalicylidene)- -1,2-cyclohexanediaminato]
manganese(III) chloride (13.0 g, 20.5 mmol). The reaction mixture
was then stirred at room temperature for 12 hours, evaporated to
dryness, partitioned between dichloromethane (3.times.200 mL) and
water (400 mL), and the aqueous layer further extracted with
dichloromethane (3.times.200 mL). The combined organic layers were
then dried, evaporated to dryness, and the crude product purified
by flash chromatography eluting with 1:9 dichloromethane/hexane
gradually increasing to 2:1 dichloromethane/hexane. The desired
bromo-substituted alkoxyamine, 1, was obtained as a white solid,
mp. 45-46.degree. C. Yield 72%; .sup.1H NMR (CDCl.sub.3)
.delta.:0.60, 0.95, 1.09, 1.21 (each br s, 12H, CH.sub.3),
1.24-1.58 (m, 6H CH.sub.2), 1.42 (d, J=4 Hz, 3H, CH.sub.3), 4.71
(Abq, J=4 Hz, 1 H, CH), and 7.10 and 7.20 (Abq, J=8 Hz, 4 H, ArH);
.sup.13C NMR (CDCl.sub.3): .delta.17.20, 20.35, 23.52, 34.21,
34.43, 60.08, 82.66, 127.30, 128.32, 135.86, and 146.17; mass
spectrum (EI) m/z 339/341 (1:1).
Example 2
Synthesis Of A Macromolecular End Capper
[0066] Polymerization of 4-vinyltriphenylamine with 1 to provide P1
(FIG. 1): A mixture of the bromo-substituted alkoxyamine 1 (9.50 g,
1.5 mmol) and 4-vinyltriphenylamine (9.97 g, 36.8 mmol, 25
equivalents) was dissolved in chlorobenzene (10 mL) and the
reaction mixture heated at 125.degree. C. for 24 hours. The viscous
solution was then precipitated twice into methanol (500 mL)
followed by redissolution into dichloromethane (25 mL) and
precipitation into hexane (500 mL). The purified polymer was
collected by vacumn [sic] filtration and dried to give the
bromo-phenyl-terminated poly(vinyltriphenylamine) as an off-white
solid (7.78 g, 74%); .sup.1H NMR (CDCl.sub.3): .delta.0.95-1.20
(minor peaks due to TEMPO end group), 1.40-2.20 (m, 3 H CH and
CH.sub.2 of backbone) and 6.50-7.20 (m, 14 H, ArH); GPC (Pst
equivalent Mn=2300, PDI=1.22).
Example 3
Synthesis Of A Macromolecular End Capper
[0067] Polymerization of N-vinylcarbazole with 1 to provide P2
(FIG. 1): A mixture of the bromophenyl-substituted alkoxyamine 1
(0.50 g, 1.5 mmol) and N-vinylcarbazole (7.10 g, 36.8 mmol. 25
equivalents) was dissolved in chlorobenzene (7.0 mL) and the
reaction mixture heated at 125.degree. C. for 24 hours. The viscous
solution was then precipitated twice into methanol (500 mL)
followed by redissolution into dichloromethane (25 mL) and
precipitation into hexane (500 mL). The purified polymer was
collected by vacuum filtration and dried to give the
bromophenyl-terminated poly(vinylcarbazole) as an off-white solid
(5.92 g, 78%); .sup.1H NMR (CDCl.sub.3): .delta.0.95-1.20 (minor
peaks due to TEMPO end group), 1.40-2.20 (m, 3 H, CH and CH.sub.2
of backbone) and 6.10-7.20 and 7.50-8.00 (m, 8 H, ArH); GPC PSt
equivalent Mn=2000, PDI=1.28).
Example 4
Synthesis Of A Macromolecular End Capper
[0068] Polymerization of 2-styryl-5p-methylphenyloxadiazole with 1
to provide P3 (FIG. 2): A mixture of the bromo-substituted
alkoxyamine 1 (0.50 g, 1.5 mmol) and
2-styryl-5-p-methylphenyloxadiazole (7.70 g, 29.4 mmol, 20
equivalents) was dissolved in chlorobenzene (7.5 mL) and the
reaction mixture heated at 125.degree. C. for 16 hours. The viscous
solution was then precipitated twice into methanol (500 mL)
followed by redissolution into dichloromethane (25 mL) and
precipitation into hexane (500 mL). The purified polymer was
collected by vacumn filtration and dried to give the
bromophenyl-terminated poly(oxadiazole) as an off-white solid (6.64
g, 81%); .sup.1H NMR (CDCl.sub.3) .delta..0.90-1.20 (minor peaks
due to TEMPO end group), 1.40-2.20 (m, 3 H, CH and CH.sub.2 of
backbone), 2.40 (br s, 3 H, CH.sub.3), and 6.50-7.20 and 7.40-8.00
(m, 8 H, ArH); GPC (PSt equivalent Mn=2800, PDI=1.18).
Example 5
Synthesis Of A Macromolecular Initiator
[0069] Preparation of poly(di-n-hexylfluorene) end capped with
alkoxyamine substituents P4 (FIG. 2): A Schlenk tube containing 700
mg(2.54 mmol) of bis(1,5-cyclooctadiene) nicket(0), 450 mg (2.9)
mmol) of 2,2'-bipyridyl,) 0.2 mL of 1,5-cyclooctadiene, 6 mL of dry
DMF and 6 mL of dry toluene was heated under Argon to 80.degree. C.
for 0.5 hr. Then 554 mg(1.125 mmol) of
2,7-dibromo-9,9-di-n-hexylfluorene and 132 mg(0.3875 mmol) of the
bromoarylalkoxyamine 1 dissolved in 6 mL of degassed toluene were
added under argon to the dark blue reaction mixture. Upon addition
of the monomers, the color turned to reddish-brown and the
viscosity increased. After heating for 1 day in the dark, the hot
polymer solution was precipitated into a solution of 100 mL conc.
HCL, 100 mL of methanol, and 100 mL of acetone. After isolating the
crude product via filtration, the alkoxyamine capped polymer was
reprecipitated into a mixture of acetone and methanol for further
purification: Mn=5000, PDI=1.8; .sup.1H NMR (CDCl.sub.3) .delta..
7.4-8 (multiplet, aromatic protons), 2.05 (br singlet,
(.alpha.-methylene protons of hexyl groups), 1.9 (multiplet,
remaining --CH.sub.2-- signals of the n-hexyl substituents) and 0.8
(multiplet, --CH.sub.3).
Example 6
Macromolecular Initiation
[0070] Polymerization of TEMPO-functionalized poly(fluorene) with
styrene, P5 (FIG. 3): A mixture of the alkoxyamine-substituted
poly(fluorene) P4 (Mn=5,000, PDI=1.80), (0.25 g, 0.05 mmol) and
styrene (0.30 g, 2.9 mmol, 30 equivalents per chain end) was
dissolved in chlorobenzene (0.5 mL) and the reaction mixture heated
at 125.degree. C. for 24 hours. The viscous solution was then
precipitated twice into methanol (500 mL) followed by redissolution
into dichloromethane (25 mL) and precipitation into hexane (500
mL). The purified polymer was collected by vacuum filtration and
dried to give the ABA triblock copolymer,
polystyrene-poly(fluorene)-poly- styrene P5 as an off-white solid
(0.45 g, 82%); .sup.1H NMR (CDCl.sub.3). .delta.0.70-0.80 and
1.0-1.1 (peaks due to poly(fluorene) n-hexyl substitutents,
1.40-2.20 (m, CH and CH.sub.2 of polystyrene backbone and peak due
to .alpha.-methylenes of n-hexylfluorene substituents)), 6.40-7.20
(m, ArH from poly(styrene) and poly(fluorene)) and 7.50-7.80 (m,
ArH from poly(fluorene)); GPC (PSt equivalent Mn=9500,
PDI=1.62).
Example 7
Macromolecular Initiation
[0071] Polymerization of TEMPO-functionalized poly(fluorene) P4
with 4-vinyltriphenylamine, P6 (FIG. 3): A mixture of the
alkoxyamine-substituted poly(di-n-hexylfluorene) P4 (Mn=5,000,
PDI=1.80), (0.25 g, 0.05 mmol) and 4-vinyltriphenylamine (0.79 g,
2.9 mmol, 30 equivalents per chain end) was dissolved in
chlorobenzene (0.75 mL) and the reaction mixture heated at
125.degree. C. for 24 hours. The viscous solution was then
precipitated twice into methanol (250 mL) followed by redissolution
into dichloromethane (10 mL) and precipitation into hexane (250
mL). The purified polymer was collected by vacuum filtration and
dried to give the ABA triblock copolymer,
poly(vinyltriphenylamine)-poly(-
di-n-hexylfluorene)-poly(vinyltriphenylamine) P6 as an off-white
solid (0.93 g, 90%); .sup.1H NMR (CDCl.sub.3). .delta.0.70-0.80 and
1.0-1.1 (peaks due to n-hexyl substituents of the poly(fluorene)),
1.40-2.20 (m, CH and CH.sub.2 of poly(vinyltriphenylamine) backbone
and peaks due to the .alpha.-methyemes units of the n-hexyl
substituents on the poly(fluorene) units), 6.40-7.20 (m, ArH from
poly(vinyltriphenylamine) and poly di-n-hexyl (fluorene)) and
7.50-7.80 (m, ArH from poly (di-n-hexyl (fluorene)); GPC PSt
equivalent Mn 10,500, PDI=1.68).
Example 8
Polymerization With Macromolecular End Cappers
[0072] (a) Preparation of ABA Copolymer (P7) [85/15
Poly(9,9-di-n-hexylfluorene-co-9,10-anthracene)] End Capped with
Poly(2-styryl-5-2-5p-methylphenyloxadiazole) (FIG. 4): Into a
Schlenk tube containing 242 mg (0.88 mmol) of
bis(1,5-cyclooctadiene) nickel (0), 95 mg (0.88 mmol) of
1,5-cyclooctadiene and 137.3 mg (0.88 mmol) of 2,2'-bipyridyl was
placed 3 mL of dry DMF and 3 mL of toluene. The solution (blue) was
heated to 80.degree. C. for 0.5 hours and a degassed mixture of 200
mg (0.41 mmol) of 2,7-dibromo-9,9-di-n-hexylfluorene, 27 mg (0.05
mmol) of 9,10-dibromoanthracene and 200 mg (0.07 mmol) of the
bromophenyl-terminated polyoxadiazole P3 described previously
(Mn=3000) in 3 mL of degassed toluene were added. Upon addition of
the monomers, the reaction color turned reddish-brown and the
mixture became more viscous. The reaction mixture was heated for 24
h and the hot polymer solution precipitated into 105 mL of a
equivolume mixture of conc HCl, methanol and acetone. After
isolation of the polymer by filtration a chloroform solution was
reprecipitated into acetone/methanol: 286 mg, (83%), Mn=13,008,
PDI=1.9. Based on GPC analysis, the Mn of the DHF/ANT block was
7008 g/mol. .sup.1H NMR resonances for the aliphatic protons of the
oxadiazole block were observed at .delta.1.4-2.2, and 2.4. The
aliphatic resonances of the DHF units appeared at 0.75, 1.1 and
2.08. The combined aromatic resonances of the block copolymer
appeared as broad multiplets at .delta.6.31-8.10.
[0073] (b) Preparation of ABA Block Copolymer (P8) of 85/15
Poly(9,9-di-n-hexyl fluorene-co-9,10-anthracene) End Capped with
Poly (vinyl triphenylamine) (FIG. 5): This material was prepared as
described above using the following quanitites: 190 mg (0.127 mmol)
of p-bromophenyl substituted poly(vinyl triphenylamine) PVTPA, P1
(Mn=1500 g/mol), 541 mg (1.1 mmol)
2.7-dibromo-9,9-di-n-hexylfluorene, 51 mg (0.15 mmol)
9,10-dibromoanthracene, 632 mg (2.3 mmol) bis(1,5-pyclooctadiene)
nickel (0), 248 mg (2.3 mmol) 1,5-cyclooctadiene, 359 mg (2.3 mmol)
bipyridyl in a mixture of 10 mL of toluene and 5 mL of DMF.
Reprecipitation yielded 489 mg (85%) of the ABA blocks copolymer
P8; Mn=30,306, PDI-2.3, .sup.1H NMR resonances for the PVTPA block
were observed at .delta.1.40- 2.20 and 6.50-7.20. The aliphatic
resonances for the DHF units appeared at .delta.0.82, 1.17 and
2.10. The aromatic resonances for the DHF and ANT units appear at
.delta.7.27-8.0. Based on GPC analysis with on polystyrene
standards, the Mn of the DBF/ANT block was ca 27,300 g/mol.
Example 9
Preparation Of Block-Graft Copolymers
[0074] (a) 2-7-Dibromo-9,9-bis(4-vinylphenyl)methyl)fluorene
(BVPBr2F) (FIG. 6): 20.0 g (62 mmol) of 2,7-dibromofluorene and
22.9 g (150 mmol) of p-chloromethylstyrene were dissolved in 100 mL
of toluene and 50 mL of NaOH (50 wt % in water) was added to the
above solution. 0.1 g of tetra(n-butyl)ammonium bromide was added
to the above mixture as a phase transfer catalyst. The color of
mixture turned dark brown as soon as phase transfer catalyst was
added. The mixture was stirred at room temperature for 12 hours.
Ethyl acetate was added and the organic phase washed with water
several times to remove NaOH. The organic layer was dried over
anhydrous magnesium sulfate and the solvent was removed by rotary
evaporator. The product was obtained by precipitating against
n-hexane and methanol. The yield was 28 g (81%). .sup.1H NMR
(CDCl.sub.3) .delta..7.5-7.0(m, 6H), 6.9 (d, 4H), 6.5(d, 4H),
6.5-6.3(q, 2H), 5.5(d, 2H), 5.0(d, 2H), 3.2(s, 4H);.sup.13C NMR
(CDCl.sub.3), .delta.. 150.1, 138.9, 136.5, 135.8, 135.5, 130.5,
130.3, 127.8, 125.3, 121.3, 120.6, 113.2, 57.2, 45.0.
[0075] (b)
1-((4-(2,7-dibromo-9-((4-(2,2,6,6-tetramethylpiperidyloxy)ethyl-
)phenyl)
methyl)fluorene-9-yl)methyl)phenyl)ethoxy)-2,2,6,6-tetramethylpip-
eridine, (Br2BTFLUO) (FIG. 6): To a solution of BVPBr2F (15.0 g, 27
mmol) and 2,2,6,6-tetramethylpiperidinyloxy (TEMPO) (24.0 g, 154
mmol) in 1:1 toluene/ethanol (1000 mL) was added
(N,N'-bis(3,5-di-tert-butylsalicylide- ne)-1,2-cycohexanediaminato)
manganese (III) chloride (16.8 g, 26.5 mmol) followed by
di-tert-butyl peroxide (24 g, 164 mmol) and sodium borohydride (12
g, 316 mmol). The reaction mixture was then stirred at room
temperature for 16 hours, evaporated to dryness, is partitioned
between dichloromethane (250 mL) and water (400 mL), and the
aqueous layer further extracted with dichloromethane (3.times.250
mL). The combined organic layers were then dried, evaporated to
dryness, and the crude product purified by flash chromatography
eluting eith n-hexane:ethyl acetate (50:1). The desired alkoxyamine
was obtained as a white solid and the yield was 8.0 g (34%).
.sup.1H NMR (CDCl.sub.3) .delta.7.5-7.1 (m, 6H), 6.9(d, 4H), 6.4(d,
4H), 4.5(q, 2H), 3.3(s, 4H), 1.5-0.3(m, 42H); .sup.13C NMR
(CDCl.sub.3).delta.:150.4, 143.8, 138.8, 134.7, 130.2, 129.8,
128.0, 126.9, 126.0, 121.0, 120.4, 82.9, 59.8, 57.1, 44.8, 40.3,
34.2, 23.0, 20.3, 17.2; mp 65-67.degree. C.
[0076] (c) Grafting Polystyrene on Br2BTFLUO, P9 (FIG. 7): Into a
dry vial were introduced the initiator Br2BTFLUO (500 mg, 0.57
mmol), styrene (295 mg, 2.84 mmol) and acetic anhydride (400 mg.
3.9 mmol). The solution was degassed and sealed under argon before
heating to 125.degree. C. for 16 hours. The molecular weight of
polystyrene could be controlled by the feed ratio of styrene and
the initiator. The polymer was dissolved in chloroform and then
precipitated into methanol. After filtering and drying under
vacuum, a white solid was obtained; (90%) Mn=5766, PDI=1.15;
.sup.1H NMR (CDCl.sub.3) .delta.. 0.9-2.5 (polystyrene and
initiator aliphatic resonances), 3.2 (PhCH.sub.2), 4.0
(CH.sub.3CHPh) 6.3-7.5 (polystyrene and initiator aromatic
resonances); Tg=100.degree. C.
[0077] (d) Yamamoto Polymerization (FIG. 8): The statistical
copolymers P10 from 2,7-dibromo-9,9-di-n-hexylfluorene and the
2,7-dibromofluorene containing polystyrene, P9, were synthesized
through nickel (0) mediated Yamamoto polymerization. A Schlenk tube
containing 6 mL toluene, 6 mL DMF, bis(1,5-cyclooctadienyl) nickel
(0) (460 mg, 1.67 mmol) and 261 mg (1.67 mmol) of 2,2'-bipyridyl
and 1,5-cyclooctadiene (180 mg, 1.67 mmol) (molar ratios, 1:1:1)
was heated under nitrogen to 80.degree. C. for 0.5 hr. The monomers
Br2DHF (443 mg, 0.9 mmol) and 577 mg (0.1 mmol) of P-9, molecular
weight 1K, dissolved in 6 mL toluene were added to the above
solution and the polymerization was maintained at 80.degree. C. for
24 hours. 5 Mol % of 2-bromo-9,9-di-n-hexylfluorene was added with
monomers for end-capping. The polymer P10 was precipitated from an
equivolume mixture of conc. HCl, methanol and acetone. The isolated
polymer was dissolved in chloroform and re-precipitated in
methanol-acetone (1: 1). Finally, the polymer was dried at
60.degree. C. under vacuum; 85%, Mn=23, 901, PDI=2.65, .sup.1H NMR
(CDCl.sub.3) .delta.. 0.9-2.4 polystyrene and initiator core
aliphatic resonances), 0.8, 1.2, 2.1 (DHF aliphatic resonances),
6.2-7.2 (polystyrene aromatic resonances), 7.5-8.0 (DHF aromatic
resonances); Tg 98.degree. C.;.lambda..sub.max(THF)=384 nm.
[0078] (e) Nickel-Mediated Copolymerization of Br2BTFLUO and
Br2DHF, P11 (FIG. 9): The statistical copolymers from
2,7-dibromo-9,9-di-n-hexyl fluorene (Br2DHF) and the
TEMPO-functionalized monomer Br2BTFLUO were prepared as described.
Into a Schlenk tube was placed 460 mg (1.67 mmol) of
bis(1,5-cyclooctadiene) nickel (0), 261 mg (1.67 mmol) of
bipyridyl, 180 mg (1.67 mmol) of 1,5-cyclooctadiene in 12 mL of a
1:1 DMF/toluene solvent mixture and the contents heated to
80.degree. C. for 0.5 h. Then a mixture of 418 mg (0.85 mmol) of
2,7-dibromo-9,9-di-n-hexylfluorene, 88 mg (0.10 mmol) of the
TEMPO-functionalized initiator Br2BTFLUO and 21 mg (0.05 mmol) of
2-bromo-9,9-di-n-hexylfluorene in 6 mL of toluene was added and the
mixture heated at 80.degree. C. for 24 h. The polymer was
precipitated and purified as described previously. 82%, Mn=25,918,
PDI=3.5; .sup.1H NMR (CDCl.sub.3) 0.7-2.1 (aliphatic protons of DHF
and initiator units), 6.8-7.9 (aromatic protons of DHF and
initiator units), 3.5 (PhCH.sub.2--), 4.6 (CH.sub.3CHO--);
Tg-109.degree. C.
[0079] (f) Graft Polymerization of Poly(styrene) to the Copolymer,
P11; alternate preparation of P10: Into a flask with N.sub.2 was
placed 100 mg of the polymer P11 (90/10 DHF/BTFLUO), 1.1 g of
distilled styrene, and 10 mg of acetic anhydride, and the reaction
mixture was heated to 125.degree. C. for 24 hr. The solution was
precipitated into methanol followed by filtration. The solid was
redissolved in dichloromethane and reprecipitated into hexane to
yield the purified polymer P10.
* * * * *