o,p-Polyaniline: A new form of a classic conducting polymer

Article abstract of DOI:10.1021/ma021343f

A new o-PANI-co-p-PANI copolymer was prepared in order to allow for the introduction of solubilizing and function-enhancing substituents on the conducting polymer backbone without concomitant loss of conductivity. An urea-protected trimeric aniline macrom

Full text of DOI:10.1021/ma021343f

4368
Macromolecules 2003, 36, 4368-4373
o,p-Polyaniline: A New Form of a Classic Conducting Polymer
Ra ch el E. Wa r d a n d Ta r a Y. Meyer *
Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260
Received August 16, 2002; Revised Manuscript Received February 4, 2003
ABSTRACT: A new o-PANI-co-p-PANI copolymer was prepared in order to allow for the introduction of
solubilizing and function-enhancing substituents on the conducting polymer backbone without concomitant
loss of conductivity. An urea-protected trimeric aniline macromonomer with para-ortho-para connectivity
and bromine end groups was condensed using palladium catalysis with a di-BOC-protected trimeric aniline
comonomer with all para connectivity and amine end groups to give 5p,o-PANI. The new polymer has a
repeat unit consisting of five para-substituted aniline rings for every one ortho-substituted aniline ring.
The regioregularity of 5p,o-PANI (Mn ) 14 000, GPC in NMP, polystyrene standards) was established
using 1H NMR, 13C{H} NMR, and IR spectroscopy. Analogous with p-PANI, the 5p,o-PANI exhibited
three distinct oxidation states. The conductivity of blends of 5p,o-PANI and PVC was on the same order
of magnitude as the conductivity of PANI films prepared under the same conditions.
In tr od u ction
We have prepared a new copolymer of ortho- and
para-substituted polyaniline that keeps the fundamen-
tal conducting backbone of polyanilines while allowing
for property and functionality enhancing derivatization.
The desire to tailor conducting polymers for particular
applications has resulted in a variety of interesting
modifications to the basic conducting chains.1 The goals
of these derivatizations include increasing solubility,
optimizing processability, and introducing recognition
elements to improve their performance as sensors.
Polyaniline, which is unique among conducting poly-
mers for its chemical and environmental stability,
tunable electrical conductivity, and unique optical prop-
erties,2 has been thus far limited in its potential for
application because, relative to other well-known con-
ducting systems such as polythiophene, it cannot be
easily modified without a concomitant sacrifice in
conductivity.
F igu r e 1. Steric interactions of polyaniline isomers.
Herein, we report the synthesis and characterization
of a new polyaniline derivative (para)5-ortho-polyaniline
(5p,o-PANI) with tert-butoxycarbonyl (BOC) and urea
protecting groups that contains five para-substituted
aniline repeat units for every one urea-protected ortho-
substituted unit. To our knowledge, this is the first
example of polyaniline containing a regularly incorpo-
rated ortho-substituted ring.
We hypothesized that the periodic introduction of
ortho-substituted anilines into the main chain of p-
polyaniline would address the functionalization prob-
lem. The fundamental challenge in modifying p-poly-
aniline is that the introduction of substituents onto the
rings exacerbates the puckering caused by ortho-ortho
interactions (Figure 1). Since conductivity is a function
of π-overlap along the polymer chain, steric interactions
that decrease planarity adversely affect the conductive
properties. Functionalization at the 4- and 5-positions
of ortho-substituted anilines incorporated into the chain
will not introduce this type of unfavorable steric inter-
action.
Resu lts
Syn th esis a n d Ch a r a cter iza tion . To incorporate
ortho-substituted repeat units into a p-polyaniline chain,
it was necessary to construct a macromonomer contain-
ing the preformed ortho-para linkages. While the
palladium-catalyzed coupling reaction that we use to
assemble the final structure allows us to precisely
control the polymer’s microstructure, it is not an ef-
ficient process for ortho couplings. To circumvent this
problem, we synthesized 1,2-di(N-p-bromophenylami-
no)benzene, which contains a built-in o-aniline moiety.
Initial unsuccessful attempts at coupling this mac-
romonomer with p-phenylenediamine established that
the diamine moiety of the macromonomer could not be
left unprotected, however, since its ortho-orientation is
ideal for chelating deactivation of the palladium catalyst
(Figure 2).
Our approach to the synthesis of these o- and p-
polyanilines relies on the elegant palladium-catalyzed
amination of aryl halide reaction developed by the
Buchwald and Hartwig groups.3 Since the Pd-catalyzed
coupling of aryl halides and arylamines is a regiospecific
reaction, it is especially useful for the controlled syn-
thesis of PANI derivatives. To date, this coupling
reaction has been used by our group and others to
prepare m-,4-6 p-,6,7 and hyperbranched-PANI4 deriva-
tives as well as discrete oligomers of both m-8 and
p-PANI.9
Protecting the diamine moiety as an imidazolone was
both effective and synthetically facile. Other candidate
protecting groups either led to the urea indirectly, e.g.,
10.1021/ma021343f CCC: $25.00 © 2003 American Chemical Society
Published on Web 05/14/2003

Macromolecules, Vol. 36, No. 12, 2003
o,p-Polyaniline 4369
Sch em e 3
F igu r e 2. Ortho orientation of 2° amines promotes coordina-
tion of the palladium catalyst.
Sch em e 1
synthesis of pure p-PANI oligomers by Buchwald and
co-workers.7 A typical polymerization was performed in
dry THF using 1.4 equiv of NaOtBu per halide with Pd2-
dba3 and 2-(di-tert-butylphosphino)biphenyl catalyst.
The tan or pale purple copolymers were isolated after
workup in 13-51% yield, depending on reaction condi-
tions.
Sch em e 2
Catalyst loadings of 1.5 mol % gave the best results.
Higher loadings produced largely insoluble materials,
and lower loadings gave primarily short oligomers.
Polymers prepared using the optimal loading were
highly soluble in THF and NMP, slightly soluble in
CDCl3, and completely insoluble in methanol and hex-
anes. All other data discussed in this report correspond
to reaction mixtures using 1.5 mol % catalyst loading.
We speculate that the higher catalyst loadings may be
promoting cross-linking by double coupling at a single
N center.
Although the 1H NMR spectrum of 5p,o-PANI exhibits
the peak broadness that is typical of macromolecules,
a primary amine end-group resonance (δ 4.4) is visible
in the spectrum, and its integration relative to the aryl
region appears to correlate with the molecular weight
of the polymer. The identity of the 1° and 2° amine
resonances at δ 4.46 and 7-7.4 (THF-d8), respectively,
was confirmed by exchange with D2O. The polymer also
exhibited the expected BOC resonance at δ 1.39. Ad-
ditionally, no trace of phosphine incorporation was
detected by 31P NMR spectroscopy, which establishes
that ligand incorporation into the polymer chain by
phosphine aryl exchange is not significant.11
To aid in the interpretation of the complex NMR
spectra of the copolymer and to establish that the coup-
ling was efficacious, a model oligomer, 4, was prepared
by coupling macromonomer 1 with excess p-toluidine
(Scheme 3). Model compound 4 exhibited unique spec-
tral features in the 13C NMR spectrum, including the
urea resonance found at δ153 and the carbon-2 reso-
nance of the meta ring which appeared distinctly upfield
of all the other aryl resonances at δ 109.
BOC, or were labile under the reaction conditions, e.g.,
alkylsilanes. Although initially we prepared macromono-
mer 1 by protecting the preassembled trimer, it proved
synthetically easier to prepare the urea-protected spe-
cies by performing an Ullmann-Goldberg coupling of
1,3-dihydrobenzimidazol-2-one with excess p-bromoben-
zene, following the procedure of Sugahara et al.10
Column chromatography allowed for effective separation
of the excess p-dibromobenzene from the monomer and
gave a 28% yield of 1,3-bis(4-bromophenyl)-1,3-dihy-
drobenzoimidazol-2-one, 1, as a white solid. The struc-
ture of macromonomer 1 was confirmed using 1H NMR,
13C NMR, and elemental analysis.
Coupling of urea macromonomer 1 and BOC-protect-
ed PANI trimer9 2 gave the copolymer 3, 5p,o-PANI (see
Scheme 2). Our initial attempts to polymerize 1 with
p-phenylenediamine or with p-phenylenediamine dihy-
drochloride to give a 3p,o-PANI produced an insoluble
material. Switching from the simple diimine to the
BOC-protected trimer, 2, resolved the problem. This
monomer was originally prepared and used for the
The 13C NMR spectrum of polymer 3 establishes that
the expected alternating copolymer structure is present.
Collection of the 13C NMR data at 330 K in THF-d8
greatly simplifies the spectrum relative to room tem-
perature spectra. By comparison to the spectrum for
monomers 1 and 2 and the model oligomer 4, resonances
consistent with the four different aryl ring substitution
patterns (A-D) expected in the repeating unit of the
polymer can be identified (Figure 3). Particularly note-

4370 Ward and Meyer
Macromolecules, Vol. 36, No. 12, 2003
F igu r e 3. 13C{H} NMR spectrum of 3 can be assigned by comparison to monomers 1 and 2 and to model compound 4.
worthy are the CO resonances for the urea and BOC
carbonyl carbons at δ 153 and 154, respectively, and the
resonance at δ 115, which is assignable to the unsub-
stituted carbons of the D ring. Moreover, the resonances
associated with the unsubstituted carbons of the ortho-
substituted A ring (δ 109 and 123) and the BOC
protecting group (δ 28.5) are sufficiently clean and well
resolved that they can be integrated if the 13C NMR data
are acquired under conditions that minimize NOE.
Assuming that BOC cleavage is minimal, these integra-
tions establish that the units derived from macromono-
mers 1 and 2 are present in a 1:1 ratio. There were also
some resonances in the spectrum that could be at-
tributed to end-group rings (E and F ), but their low
intensities and overlap with repeating unit resonances
make it difficult to assign them unambiguously.
tan color to brown, consistent with the formation of the
LB form of the polymer. The deep purple EB form was
achieved by similarly heating fresh films to 185 °C in
air for 8 h. Finally, the characteristically green ES
polymer was generated by immersing a third set of films
in an HCl/Et2O solution for 30 min and allowing the
films to dry in air for several hours. Similar films for
FT-IR spectroscopy were also prepared on KBr salt
plates by the slow evaporation of THF, followed by the
appropriate oxidation/doping procedure.
The electronic spectra of oxidized samples of 5p,o-
pani, 3, suggest that, by analogy with spectra of
similarly prepared p-PANI samples, it should be con-
ducting. Notably, as the polymer is oxidized to 5p,o-
PANI-EB and 5p,o-PANI-ES, new bands appear in the
visible region of the spectrum (Figure 4). Furthermore,
5p,o-PANI-ES exhibits a gradual increase in absorption
intensity of a broad band at ca. 525 to beyond 1100 nm;
the presence of this free carrier tail is consistent with
the delocalization of electrons expected for a highly
conjugated chain.13
The molecular weight (Mn) of the 5p,o-PANI 3 is in
the 2400-5500 range (DP ) 36-85 aniline units).
Although the molecular weight obtained by GPC in
NMP vs polystyrene standards is significantly higher,
Mn of 14 000 (PDI ) 1.75), it has been reported by both
us and others that this method overestimates the
molecular weight of polyanilines.4,12 It is worth noting
that, consistent with expectations for multiple couplings,
there was a significant difference in the GPC retention
times of the macromonomers (1 and 2) and polymer 3
under these conditions. A more realistic estimate of
molecular weight can be obtained by end-group analysis.
If we assume that the structure is in fact regioregular
and that the monomers are present in a 1:1 ratio, the
FTIR spectra of the treated polymer films also con-
firmed the changes in the oxidation state of 5p,o-PANI.
The major features of the IR spectrum of polymer 3
included a 2° amine stretch at 3333 cm-1, a carbonyl
stretch at 1706 cm-1, and aromatic (3042 cm-1) and
aliphatic (2975 and 2870 cm-1) C-H stretches (Figure
5a). Additionally, the polymer exhibits absorptions
associated with the C-H out-of-plane bending of 1,4-
substituted (828 cm-1) and 1,2-substituted (750 cm-1
)
1
molecular weight is easily calculated from both the H
aromatic rings. The cleavage of the BOC protecting
groups in the LB, EB, and ES forms of the polymer is
accompanied by a significant decrease in intensity in
the 2800-3000 region associated with aliphatic C-H
stretches.14 The IR vibrational bands at 1606 and 1509
cm-1, present in all forms of 5p,o-PANI, can be assigned
to CdC and C-C stretching and bending modes re-
ported for polyaniline. Tang et al. have assigned the
∼1600 cm-1 peak to the quinonoid ring and the ∼1500
cm-1 peak to the benzenoid ring of PANI.15 As would
be expected on the basis of this analysis, we observe that
oxidation to the ES form produces a significant change
in the 1600 cm-1 absorption; the band shifts to 1582
cm-1 and increases in intensity relative to the 1504 cm-1
peak. This shift indicates that when 5p,o-PANI is
treated with HCl, quinoid units are incorporated into
the polymer.16 Further confirmation of the formation of
the conducting ES form of 5p,o-PANI is the long
absorption tail above 2000 cm-1 that masks the N-H
NMR spectrum (integration of the primary NH vs the
entire aryl C-H region) and the chemical analysis for
Br (comparing the expected C/H/N to Br percentages).
The modest molecular weights of 2400-5500 thus
determined are consistent with the relatively poor film-
making properties that we observed for 5p,o-PANI.
Dep r otection a n d Oxid a tion of 5p,o-P ANI. Analo-
gous to p-polyaniline, dramatic color changes accompany
changes in the oxidation/doping state of 5p,o-PANI as
shown in Figure 4. Very thin films of polymer 3 were
prepared by spin casting from THF onto glass slides
using a photoresist spinner. To generate the leucoem-
eraldine base (LB), emeraldine base (EB), and emeral-
dine salt (ES) forms of 5p,o-PANI, three separate film
treatments were then applied. Buchwald and co-workers
originally developed these procedures for deprotecting
their p-polyanilines.7 Films placed in a 185 °C silica bath
in a N2 drybox and heated for 8 h turned from a pale

Macromolecules, Vol. 36, No. 12, 2003
o,p-Polyaniline 4371
F igu r e 4. UV-vis spectra and films of polymer 3 and its deprotection products: 5p,o-PANI-LB, 5p,o-PANI-EB, and 5p,o-PANI-
ES.
F igu r e 5. IR spectra of polymer 3 (a) and its deprotection and oxidation products: 5p,o-PANI-LB (b), 5p,o-PANI-EB (c), and
5p,o-PANI-ES (d).
stretching frequency. This spectroscopic feature has
been associated with high electrical conductivity and a
high degree of electron delocalization in PANI.16
Initial studies on polymer 5p,o-PANI-ES (blended
with PVC to improve film quality) show conductivities
within an order of magnitude of those measured for
p-polyaniline in similar sample preparations (∼0.2
S/cm). We plan to pursue more detailed studies of the
conductive properties of these polymers in the future.
Discu ssion
We have successfully prepared an o,p-polyaniline
derivative, 5p,o-PANI, that contains one ortho-substi-
tuted aniline ring for every five para-substituted aniline
rings. NMR and IR spectroscopy confirm the presence
of an ortho-substituted ring and unambiguously estab-
lish the regioregularity of this polymer. Furthermore,
integration of the 13C NMR spectrum suggests that

4372 Ward and Meyer
Macromolecules, Vol. 36, No. 12, 2003
1,3-dihydrobenzoimidazol-2-one (2.00 g, 14.9 mmol), p-dibro-
mobenzene (10.6 g, 44.7 mmol), potassium carbonate (4.12 g,
29.8 mmol), copper(I) iodide (0.568 g, 2.98 mmol), and dim-
ethylformamide (48 mL). The mixture was then refluxed at
150 °C for 24 h. After cooling to room temperature, the reaction
mixture was taken up in dilute ammonium hydroxide, ex-
tracted into ethyl acetate, washed with brine solution, and
finally dried with magnesium sulfate according to the proce-
dure described by Sugahara et al.10 Following purification by
column chromatography in CH2Cl2/hexanes, 1.89 g of mac-
there is no difference in the activities of the mac-
romonomers; they are present in a 1:1 ratio.
While the relatively modest size of the ortho,para-
copolymers does adversely affect their film-making
properties, it would not be expected to significantly
inhibit conductivity. Recently, several reports on the
preparation and chemical and physical properties of
oligomeric anilines have appeared in the literature.9,17-19
Because conductivity depends on intramolecular, inter-
molecular, and interdomain contributions, polymer
length is not the sole determining factor in the magni-
tude of bulk conductivity.18,20 Oligomers as small as 16
repeat units show conductivities in the 10-3 range.17 The
relatively low molecular weights are likely due to the
competing formation of cyclic oligomers, a phenomenon
that has been observed previously in the preparation
of polyanilines by Pd-catalyzed couplings.6
1
romonomer 1 (28% yield) was isolated as a white powder. H
NMR (CDCl3): δ 7.68 (d, 4H), 7.49 (d, 4H), 7.15 (s, 4H). 13C-
{1H} NMR (CDCl3): δ 152.1 (ipso, carbonyl), 133.6 (ipso),
133.0, 129.3 (ipso), 127.8, 122.8, 121.6 (ipso), 109.2. IR (film,
cm-1): 1726. EI-MS (m/z): 444 (M+). Anal. Calcd for C19H12N2-
OBr2: C, 51.38; H, 2.73; N, 6.31. Found: C, 51.21; H, 2.75; N,
6.30.
Syn th esis of 5p,o-P ANI, 3. In a glovebox were weighed
ortho-para-macromonomer, 1 (0.222 g, 0.500 mmol), PANI
trimer 2 (0.245 g, 0.500 mmol), NaOtBu (0.135 g, 1.40 mmol),
Pd2dba3 (0.009 g, 1.5 mol % Pd/amine), and 2-(di-tert-but-
ylphosphino)biphenyl (0.018 g, 0.06 mmol). The reagents were
transferred to a heavy-walled flask equipped with a Teflon-
coated valve and suspended in 2.7 mL of THF. The flask was
sealed and heated to 80 °C for 2 days. The reaction mixture
was cooled to room temperature, and the THF was removed
in vacuo. The crude product was washed by sonication using
first ether (2 × 10 mL), then H2O (2 × 10 mL), and finally
methanol (2 × 10 mL). Sonication of the remaining solids in
THF (15 mL) gave a homogeneous solution, which was added
dropwise to 40 mL of methanol, producing a fine suspension.
Collection of the precipitate gave a 45% yield of polymer 3.
The remaining 55% of the product was isolated as smaller
Con clu sion s
The ortho-para derivative of polyaniline, 5p,o-PANI,
3 exhibited the spectroscopic properties, colored oxida-
tion states, and conductive properties associated with
conducting polyaniline. These findings suggest that the
presence of the ortho-substituted aniline ring does not
critically disrupt the conjugation of the polymer or
interfere significantly with interchain interactions. The
effect on bulk conductivity of the urea-protecting group
is not clear. Although the urea carbonyl could be acting
as a spin trap and, thereby, inhibit free movement of
electrons along the backbone,21 the imidazolone ring
could also be promoting conjugation by enforcing pla-
narity along the backbone. We intend to address this
question in future studies by preparing the analogous
“unprotected” 5p,o-PANI. Finally, we are now prepared
to synthesize derivatives of 5p,o-PANI carrying substit-
uents in the A3 position of the ortho rings with the
objective of creating polyanilines with tunable conduct-
ing and physical properties.
oligomers by concentration of the filtrate. GPC (NMP): Mw
)
24 000, Mn ) 14 000, PDI ) 1.75. 1H NMR (THF-d8): δ 7.70-
6.59 (m, aryl and 2° NH), 4.46 (br, 1° NH), 1.42-1.29 (m, t-Bu).
13C{1H} NMR (THF-d8, 25 °C): δ 154.8 (ipso), 154.6 (ipso),
153.7 (ipso), 153.2 (ipso), 148.1 (ipso), 145.0 (ipso), 144.8 (ipso),
144.1 (ipso), 141.8 (ipso), 141.2 (ipso), 140.5 (ipso), 136.4 (ipso),
135.8 (ipso), 133.6, 131.7 (ipso), 131.4 (ipso), 130.9, 130.3,
129.6, 129.4, 128.8, 128.4, 128.0 (ipso), 127.4, 126.6, 125.4,
123.3, 122.6, 121.5, 121.0, 119.0, 118.3, 116.9, 116.5, 115.2,
109.5, 80.8 (ipso), 80.5 (ipso), 28.5. 13C{1H} NMR (THF-d8, 57
°C): δ 154.2 (ipso), 153.2 (ipso), 144.6 (ipso), 142.3 (ipso), 141.7
(ipso), 137.6 (ipso), 133.2, 131.4 (ipso), 129.2 (ipso), 129.0,
128.0, 127.0, 122.4, 119.13, 118.3, 115.0, 109.2, 80.2 (ipso),
28.5. IR (film, cm-1): 3333, 3042, 2975, 2870, 1709, 1607, 1509,
1325, 1162, 1058, 828, 750. UV-vis (film, λmax, nm): 297. Anal.
Calcd for (C47H44N6O5)n: C, 73.03; H, 5.75; N, 10.87; Br, 0.00.
Found: C, 70.27; H, 5.38; N, 10.26; Br, 3.26.
Exp er im en ta l Section
Gen er a l. All reactions and manipulations were performed
under an atmosphere of nitrogen either in a glovebox or by
using standard Schlenk techniques. All reagents were pur-
chased from commercial suppliers and used without further
purification unless otherwise noted. NaOtBu and 1,4-phe-
nylenediamine were sublimed. 1,3-Dihydrobbenzoimidazol-2-
one was prepared by the literature procedure.22 BOC-protected
PANI trimer, 2, was prepared using the synthetic scheme
outlined by Buchwald et al.9 Polyaniline was prepared in its
emeraldine base form by the standard procedure for the
oxidation of aniline using ammonium peroxydisulfate followed
by treatment with ammonium hydroxide.23 CDCl3 was vacuum-
transferred from P4O10. THF and THF-d8 were distilled from
Na and Na/benzophenone, respectively.
Syn th esis of Mod el Oligom er , 4. In a glovebox were
weighed 0.300 g (0.676 mmol) of ortho-para-macromonomer,
1, 0.148 g (1.385 mmol) of toluidene, 0.149 g (1.55 mmol) of
NaOtBu, 0.013 g (2 mol % Pd/amine) of Pd2dba3, and 0.017 g
(0.06 mmol) of 2-(di-tert-butylphosphino)biphenyl. The re-
agents were transferred to a heavy-walled flask equipped with
a Teflon-coated valve and suspended in 2.5 mL of THF. The
flask was sealed and heated to 80 °C for 18 h. The reaction
mixture was cooled to room temperature, diluted with CH2-
Cl2, and filtered through Celite. Hexanes were added to the
filtrate to precipitate the crude product which was subse-
quently washed with toluene to give a 33% yield of compound
1H NMR and 13C{1H} NMR spectra were acquired on Bruker
300 MHz instruments; the 13C{1H} NMR of polymer 3 was
collected on a Bruker 500 MHz spectrometer. GPC data were
acquired in NMP solvent on a Waters GPC system equipped
with phenogel columns and a Waters 410 differential refrac-
tometer calibrated using polystyrene standards. IR data were
acquired on a Perkin-Elmer Spectrum BX FT-IR system. UV-
vis data were acquired on a Perkin-Elmer Lambda 19 UV/vis/
NIR spectrometer. EI-MS data were acquired on a VG-70S (+)
EI-MS. Thin films were spun-cast on a Headway Research,
Inc., photoresist spinner model 1-EC101D-R485. Conductivity
measurements were made using the standard four-point probe
method.24
1
4 as a pale tan powder. H NMR (THF-d8): δ 7.45 (br, 2° NH,
2H), 7.41 (d, J ) 8.8 Hz, aryl, 4H), 7.18 (d, J ) 8.8 Hz, aryl,
4H), 7.06 (m, aryl, 12 H), 2.25 (s, CH3, 6H). 13C{H}-NMR (THF-
d8) δ 153.2 (ipso), 145.2 (ipso), 141.6 (ipso), 131.2 (ipso), 130.9
(ipso), 130.4, 127.9, 127.0 (ipso), 122.1, 119.7 (ipso), 116.9,
109.0, 20.8. EI-MS (m/z): 496 (M+).
R ep r esen t a t ive P r oced u r e for R em ova l of BOC-
P r otectin g Gr ou p s. Polymer 3 was cast into thin films by
spin-casting from a THF solution. These films of the BOC-
protected polymer were then heated to 185 °C for 8 h under
N2 on a silica constant-temperature bath or in an open-air oven
to produce the leucoemeraldine and emeraldine base forms of
the polymer, respectively. The emeraldine salt oxidation state
Syn th esis of 1,3-Bis(4-br om op h en yl)-1,3-d ih yd r oben -
zoim id a zol-2-on e, 1. A round-bottomed flask was loaded with

Macromolecules, Vol. 36, No. 12, 2003
o,p-Polyaniline 4373
(3) Wolfe, J . P.; Wagaw, S.; Marcoux, J .-F.; Buchwald, S. L. Acc.
Chem. Res. 1998, 31, 805. Hartwig, J . F. Angew. Chem., Int.
Ed. 1998, 37, 2046. Wagaw, S.; H., Y. B.; Buchwald, S. L. J .
Organomet. Chem. 1999, 576, 125.
(4) Spetseris, N.; Ward, R. E.; Meyer, T. Y. Macromolecules 1998,
31, 3158-3161.
(5) Kanbara, T.; Izumi, K.; Nakadani, Y.; Narise, T.; Hasegawa,
K. Chem. Lett. 1997, 1186. Kanbara, T.; Miyazaki, Y.;
Hasegawa, K.; Yamamoto, T. J . Polym. Sci., Polym. Chem.
2000, 38, 4194-4199. Goodson, F. E.; Hauck, S. I.; Hartwig,
J . F. J . Am. Chem. Soc. 1999, 121, 7527-7539. Kanbara, T.;
Nakadani, Y.; Hasegawa, K. Polym. J . 1999, 31, 206-209.
(6) Goodson, F. E.; Hartwig, J . F. Macromolecules 1998, 31,
1700-1703.
was formed by treating films with Et2O/HCl solution for 30
min with subsequent air oxidation for several hours.
Th in -F ilm P r ep a r a tion a n d Dop in g P r oced u r e for
Con d u ction Mea su r em en ts. Films of polymer 3 and PANI-
EB were drop-cast from an NMP solution containing the a 50:
50 mixture of polymer and poly(vinyl chloride) (PVC). Solutions
were dropped onto clean glass slides, and the NMP was
removed in vacuo in a vacuum desiccator. The films were
removed from the glass slide with distilled water, dried, and
subsequently placed into a vial containing HCl vapors. After
3 days, the conductivity of each film was measured using a
standard four-point probe apparatus. Current flow, I, through
each film was measured in at least two separate areas on the
film. The value of I was recorded when the applied voltage, V,
reached a minimum value. If the measured current passing
through the film was less than 1.5 × 10-8 A, the reading was
excluded from the data set. Typically at least three voltage/
current measurements were measured for each film and
averaged. Film thicknesses were measured using an L.S.
Strarrett Co. calipher that was calibrated and found to
measure to the nearest thousandth of an inch ( 2%. When
possible, three film thickness measurements were recorded
and averaged.
(7) Zhang, X.-X.; Sadighi, J . P.; Mackewitz, T. W.; Buchwald, S.
L. J . Am. Chem. Soc. 2000, 122, 7606-7607.
(8) Louie, J .; Hartwig, J . F. Macromolecules 1998, 31, 6737-
6739.
(9) Sadighi, J . P.; Singer, R. A.; Buchwald, S. L. J . Am. Chem.
Soc. 1998, 120, 4960-4976.
(10) Sugahara, M.; Ukita, T. Chem. Pharm. Bull. 1997, 45, 719-
721.
(11) Goodson, F. E.; Wallow, T. I.; Novak, B. M. J . Am. Chem.
Soc. 1997, 119, 12441-12453.
(12) Hsu, C.-H.; Peacock, P. M.; Flippen, R. B.; Manohar, S. K.;
MacDiarmid, A. G. Synth. Met. 1993, 60, 233-237.
(13) MacDiarmid, A. G.; Epstein, A. J . Synth. Met. 1995, 69, 85-
92.
(14) There is some residual aliphatic C-H absorption in the
2800-3000 region likely arising from a small percentage of
uncleaved BOC groups. We have not yet attempted to
optimize the procedure to ensure complete cleavage.
(15) Tang, J .; J ing, X.; Wang, F. Synth. Met. 1988, 24, 231.
(16) Kang, E. T.; Neoh, K. G.; Tan, K. L. Prog. Polym. Sci. 1998,
23, 277-324 and references therein.
Ack n ow led gm en t. This research was supported by
the NSF (CHE-0091499). We thank Prof. Richard
McCullough and Dr. Richard Pilston at Carnegie Mellon
University for help with conductivity measurements.
Su p p or tin g In for m a tion Ava ila ble: 1H and 13C NMR
spectra for 5p,o-PANI 3 and model oligomer 4 and GPC data
for polymer 3. This material is available free of charge via the
Internet at http://pubs.acs.org.
(17) Zhang, W. J .; Feng, J .; MacDiarmid, A. G.; Epstein, A. J .
Synth. Met. 1997, 84, 119-120.
(18) MacDiarmid, A. G.; Feng, J . Synth. Met. 1999, 100, 131-
Refer en ces a n d Notes
140.
(19) Lokshin, N. A.; Pyshkina, O. A.; Golubev, V. B.; Sergeyev,
V. G.; Zezin, A. B.; Kabanov, V. A.; Levon, K.; Piankijsakul,
S. Macromolecules 2001, 34, 5480-5486. Gao, J .; Zhang, W.;
Wang, C.; Wu, Z.; J i, Y.; Zhou, Y.; Shibata, M.; Yosomiya, R.
Macromol. Rapid Commun. 1999, 20, 560-563.
(20) MacDiarmid, A. G. Synth. Met. 1997, 84, 27.
(21) Burke, L. A. J . Polym. Sci., Polym. Phys. Ed. 1984, 22, 1987-
1989.
(1) Goto, H.; Akagi, K. Macromolecules 2002, 35, 2545-2551.
Prevost, V.; Petit, A.; Pla, F. Synth. Met. 1999, 107, 79-87.
Kitani, A.; Satoguchi, K.; Tang, T.-Q.; Ito, S.; Sasaki, K.
Synth. Met. 1995, 69, 131-132. Zotti, G.; LeClerc, M. Chem.
Mater. 1995, 7, 33-42. Bodalia, R.; Stern, R.; Batich, C.;
Duran, R. J . Polym. Sci., Polym. Chem. 1993, 31, 2123-2127.
Wang, X.-H.; Li, J .; Wang, L.-X.; J ing, X.-B.; Wang, F. S.
Synth. Met. 1995, 69, 147-147. Mattoso, L. H. C.; Faria, R.
M.; Bulhoes, L. O. S.; MacDiarmid, A. G. J . Polym. Sci.,
Polym. Chem. 1994, 32.
(2) MacDiarmid, A. G. Synth. Met. 1997, 84, 27-34. Heeger, A.
J . Synth. Met. 1993, 55-57, 3741. MacDiarmid, A. G.;
Epstein, A. J . Faraday Discuss. Chem. Soc. 1989, 88, 317.
MacDiarmid, A. G.; Epstein, A. J . Synth. Met. 1995, 69, 85.
(22) Crank, G.; Mursyidi, A. Aust. J . Chem. 1982, 35, 775-784.
(23) Mattoso, L. H. C.; MacDiarmid, A. G.; Epstein, A. J . Synth.
Met. 1994, 68, 1-11.
(24) Van der Pauw, L. J . Phillips Res. Rep. 1958, 13, 1.
MA021343F