Synthesis of luminescent rod-coil block copolymers using atom transfer radical polymerization

Article abstract of DOI:10.1021/ma020256k

The synthesis of luminescent rod-coil diblock and coil-rod-coil triblock copolymers containing oligo(p-phenyleneethynylene) as the rodlike block and polystyrene as the coil was achieved via atom transfer radical polymerization using oligo(p-phenyleneethyn

Full text of DOI:10.1021/ma020256k

5758
Macromolecules 2002, 35, 5758-5762
Synthesis of Luminescent Rod-Coil Block Copolymers Using Atom
Transfer Radical Polymerization
P . K. Tsola k is a n d J . K. Ka llitsis*
Department of Chemistry, University of Patras, GR-265 00 Patras, Greece, and
Institute of Chemical Engineering and High-Temperature Chemical Processes (ICE/ HT),
P.O. Box 1414, GR-265 00 Patras, Greece
A. God t
Max-Planck-Institut fu¨r Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany
Received February 19, 2002; Revised Manuscript Received April 12, 2002
ABSTRACT: The synthesis of luminescent rod-coil diblock and coil-rod-coil triblock copolymers
containing oligo(p-phenyleneethynylene) as the rodlike block and polystyrene as the coil was achieved
via atom transfer radical polymerization using oligo(p-phenyleneethynylene)s as the initiators substituted
with 2-halogenopropionyloxy or 4-(bromomethyl)benzyloxy groups.
In tr od u ction
Resu lts a n d Discu ssion
Our target was the synthesis of luminescent rod-coil
diblock and coil-rod-coil triblock copolymers based on
oligoPPE as the rodlike building block. For this purpose
we modified the hexyl-substituted oligoPPEs 1a and 2a
that carry terminal hydroxyl groups in order to obtain
mono- and difunctional initiators for ATRP of vinyl
monomers. The ATRP active groups 2-halogenopropio-
nyl and 4-(bromomethyl)benzyl were attached either
through the reaction of diol 1a with 2-chloropropionyl
chloride to give 1b or through the reaction of the diol
1a or 2a with R,R′-dibromo-p-xylene to give the diether
products 1c and 2c (Scheme 1). In both cases the
reagents were used in large excess. The monofunction-
alized inititator 1e was prepared through the reaction
of 1a with only 1.1 equiv of 2-bromopropionyl chloride.
Rod-coil block copolymers attract interest because of
the expected1 and experimentally found2-4 richness of
self-assembling morphologies. The formation of the
peculiar supramolecular structures is driven by the
incompatibility of the rod and the coil blocks and the
tendency of the rod blocks to order into anisotropic
structures.5 Thus, rod-coil block copolymers offer the
opportunity for engineering materials with novel prop-
erties and functions. Of particular interest to us are
rod-coil block copolymers with luminescent rod blocks.
These may offer a way to a rational design of materials
with optoelectronic properties with the additional fea-
ture of easy processing of the materials. Several ex-
amples of such copolymers with for example oligo(p-
phenylenevinylene)s,4 oligo(p-phenyleneethynylene)s,6
oligo(phenylquinoline),3 and oligo(p-phenylene)7a as the
rod block have been reported. As expected, the opto-
electronic properties vary with the supramolecular
morphology.3 Because the optical properties are also
depending on the length of the π-conjugated rod block,
monodisperse rod blocks appear as the most promising
modules. Additional low polydispersity of the coil will
enhance the control over the morphology. For achieving
this goal different techniques can be used. For example,
premade, anionically polymerized and therefore nar-
rowly distributed coil blocks were attached to monodis-
perse rods,4,6a and controlled radical polymerization
techniques were used for formation of the coil block with
the rod block acting as the initiator.4c,7a We have
described the attachment of narrowly dispersed poly-
isoprene to derivatized monodisperse oligo(p-phenyle-
neethynylene)s (oligoPPEs)6a and the use of atom trans-
fer radical polymerization (ATRP)9 of styrene with
rodlike R,ω-difunctionalized quinquephenylene or hep-
taphenylene7a as the initiator to obtain rod-coil diblock
and coil-rod-coil triblock copolymers. Herein we present
that ATRP can be applied to p-phenyleneethynylene-
based compounds as the initiators. The initiators were
prepared from suitably difunctionalized oligomers 1a
and 2a that are readily available on the gram scale.10a
Longer rods and blocks with other architectures10b can
be envisaged as a possible extension of the presented
synthetic route.
1
The structures of the initiators were proven by H
NMR spectroscopy. A characteristic change upon trans-
formation of 1a into 1b is the shift of the signal due to
the aromatic protons next to the oxygen substituent
from 6.81 (1a ) to 7.15 ppm. The integration ratio 2:3 of
the signal at 2.79 ppm that is due to the benzylic protons
of the hexyl substituents and at 1.83 ppm that is due
to the methyl groups of the propanoyl group shows that
both OH groups were substituted, giving a difunctional
1
initiator. The H NMR spectrum of the monofunction-
1
alized initiator 1e is essentially the sum of the H NMR
spectrum of 1a and of 1b, e.g., showing two AA′XX′
systems in the aromatic region and a signal for the OH
group. The integration ratio of the signals at 2.80 and
1.82 ppm was found to be 4:3. Thin-layer chromatog-
raphy showed only one spot. Therefore, it is excluded
that the isolated material is a 1:1 mixture of 1a and
1b. The transformation of 1a or 2a into 1c or 2c was
accompanied by a downfield shift of the aromatic
protons next to the oxygen substituent from 6.81 (1a )
or 6.85 (2a ) to 6.95 ppm (1c, 2c). The signal at 5.08 ppm
is assigned to the OCH2 groups. The integration ratio
of this signal and the signals at 2.80 ppm (benzylic
protons of the hexyl substituents) and at 4.50 ppm (CH2-
Br) was found to be 1:1:1. Furthermore, the ratio for
the signals at 4.50 ppm (CH2Br) and at 0.90 ppm (CH3)
is 2:3. These data are in agreement with the difunc-
tionalized inititators 1c and 2c.
10.1021/ma020256k CCC: $22.00 © 2002 American Chemical Society
Published on Web 06/14/2002

Macromolecules, Vol. 35, No. 15, 2002
Rod-Coil Block Copolymer 5759
Sch em e 1a
While at 254 nm both blocks, polystyrene and oligoPPE,
absorb light, at 350 nm only the oligoPPE absorbs light.
The obtained SEC traces (Figure 1) show no difference,
proving that the oligoPPEs are incorporated into the
1
polymers. This conclusion is supported by the H NMR
spectrum of 1b-P S 4 (Figure 2), which shows charac-
teristic signals of the oligoPPE block, i.e., signals at 0.88,
2.80, and 7.45 ppm with the expected ratio of 3:2:2.
As shown in Figure 3, SEC does not reveal residual
initiator. This indicates a high initiation efficiency. The
workup procedure (precipitation with methanol) is not
expected to remove residual initiator because of the low
solubility of the inititator in methanol. Accordingly, the
1H NMR spectra of 1b-P S, as for example the spectrum
of 1b-P S 4 (Figure 2), show no signal for residual CHCl
groups at 4.6 ppm, indicating that the polymers are
indeed triblock copolymers. New broad signals at about
4.4 and 4.3 ppm are probably due to the methinic
protons that are adjacent to the halogen atom. The same
signals are also found in the 1H NMR spectrum of
polystyrene prepared by ATRP using R,R′-dibromo-p-
xylene as an initiator (Figure 2).
Since the Tg of the coil block has a significant
influence on the ability of these copolymers to self-
assemble,1 ethyl acrylate was chosen as another vinyl
monomer to be polymerized with the rod initiators. The
polymerization of ethyl acrylate with 1b or 1c as
initiators gave unsatisfying results. SEC and NMR
spectra revealed residual 1b or 1c in the product.
Column chromatography allowed for removal of the
initiator. However, the product is most probably a
mixture of rod-coil and coil-rod-coil block copolymers
with very much varying lengths of the coil blocks. In
agreement with a mixture of di- and triblock copolymers
a
Key: (a) ClMeCH-COCl, Et3N, CH2Cl2; (b) R,R′-dibromo-
p-xylene, K2CO3, acetone; (c) MeCOCl, Et3N, CH2Cl2; (d)
BrMeCH-COCl, Et3N, CH2Cl2.
1
is the H NMR spectrum which shows multiple signals
for the aromatic protons.
A matter of concern when using compounds 1b,c,e,
and 2c as initiators in these controlled radical polymer-
izations was that the CtC bonds may not be completely
inert under the reaction conditions, although it has been
reported that they usually require the use of metathesis
catalyst in order to react efficiently.12 The Raman
spectrum of 1b-P S showed an intense signal at 2205
cm-1 that is assigned to the CtC bonds (Figure 4). To
detect potential participation of the CtC bonds in the
radical polymerization, styrene was polymerized through
ATRP (CuBr, bipy, diphenyl ether at 130 °C) with R,R′-
dichloro-p-xylene as the initiator in the presence of
diester 1d . The product was examined with SEC using
254 and 350 nm as detection wavelengths (Figure 5).
While upon detection at 254 nm two well-separated
signals due to polymer and compound 1d are detected,
only a signal due to 1d is detected at 350 nm. Incorpo-
ration of 1d by chain transfer reactions or through the
radical addition to the CtC bond would result in two
signals at both wavelengths.13 This proves that the Ct
C bonds do not participate in the polymerization process.
Additionally, the rather narrow molecular weight dis-
tributions obtained when using 1b,c, and 2c as initia-
tors in the polymerization of styrene exclude addition
to CtC bonds which should result in branching and/or
cross-linking and therefore in broad and possibly mul-
timodal distributions.
The functionalized rods were used as ATRP initiators
in the presence of CuBr and an amine to polymerize
styrene and ethyl acrylate (Scheme 1). Multiple alter-
ations of the reaction conditions [bipyridine (bipy) or
N,N,N′,N′,N′′-pentamethyldiethylenetriamine (PMDE-
TA); polymerization in diphenyl ether or in the bulk]
were made as to achieve the best possible control of the
polymerization (Table 1). CuBr was chosen also for 1b
that carries chlorine substituents because halogen
exchange is expected to increase the rate of initiation
relative to the rate of propagation leading to better
control over the polymerization.11 A wide range of
molecular weights were obtained using the different
catalytic systems. When CuBr/PMDETA was used, the
polymerization of styrene with the initiators 1b and 1c
gave coil-rod-coil triblock copolymers with high mo-
lecular weights, while with CuBr/bipy the obtained
molecular weights did not exceed 10 000. Triblock
copolymers with low molecular weights were also ob-
tained when the initiator 2c was used along with CuBr/
PMDETA. Regardless of the catalytic system used, the
polydispersity index ranged between 1.30 and 1.65. The
polymerization of styrene using 1e as the initiator
resulted in rod-coil diblock copolymers. As found in the
case of the difunctional initiators, CuBr/PMDETA gave
higher molecular weight polymer than CuBr/bipy with
a polydispersity index of 1.23 and 1.19, respectively.
To prove the incorporation of the rigid initiator into
the polymeric chain, a sample of 1b-P S 3 was examined
with size exclusion chromatography (SEC) using differ-
ent wavelengths for detection, i.e., 254 and 350 nm.
The initiators as well as the polystyrene block copoly-
mers were investigated with absorption and emission
spectroscopy in dilute solution. The UV absorption
spectrum of copolymer 1c-P S and the emission spectra

5760 Tsolakis et al.
Macromolecules, Vol. 35, No. 15, 2002
Ta ble 1. Rea ction Con d ition s a n d Molecu la r Weigh t Ch a r a cter istics of th e Syn th esized Block Cop olym er s
GPC results
d
polymer
[styrene]0/[I]0
amine
styrene/DPEc (v/v)
Mn,theo
Mn
Mw
PDI
1b-P S 1a
1b-P S 2b
1b-P S 3b
1b-P S 4b
1e-P S 1a
1e-P S 2a
1c-P S 1a
1c-P S 2a
2c-P S 1a
2c-P S 2b
2c-P S 3b
525
146
58
PMDETA
PMDETA
bipy
3
54 600
15 200
6 050
53 600
11 400
5 500
69 850
18 500
7 900
1.30
1.62
1.44
1.48
1.19
1.23
1.47
1.60
1.56
1.65
1.37
3
3
58
bipy
3
6 050
6 200
9 200
350
525
960
1311
1311
bipy
1
36 400
54 600
99 850
136 350
136 350
136 350
227 250
1 300
1 550
PMDETA
PMDETA
PMDETA
PMDETA
PMDETA
PMDETA
3
44 600
93 700
33 500
2 700
54 800
137 800
53 700
4 200
3
3
6
bulk
bulk
3 100
13 600
5 100
18 600
Reaction temperature: 110 °C. Reaction temperature: 130 °C. c DPE: diphenyl ether. Mn,theo ) 104([styrene]0/[I]0) or Mn,theo
)
a
b
d
104(mmolstyrene/mmolinitiator) (for bulk polymerization) assuming complete monomer conversion.
F igu r e 1. SEC chromatograms of 1b-P S 3 in THF recorded
at 254 nm (s) and 350 nm (- - -).
of the copolymers 1b-P S, 1c-P S, and 2c-P S are pre-
sented in Figure 6. In contrast to the absorption spectra,
the emission spectra exhibit two well-distinguished
bands which is probably due to vibronic coupling.6a,d,14
There is a 40-50 nm red shift of the emission of the
copolymer 2c-P S compared to that of 1b-P S and 1c-
P S due to the longer conjugation length of the rod block.
The 7 nm blue shift of the emission spectrum of the
copolymer 1b-P S compared to that of the copolymer 1c-
P S is attributed to the different contribution of an ether
and an ester group to the electronic density of the rigid
conjugated part. The emission spectra of the initiators
and their corresponding copolymers are essentially
identical. This is taken as an additional proof for the
integrity of the CC triple bonds in the block copolymers.
Preliminary examination of the photoluminescence of
the copolymers in solid state (thin films) was also
performed. To investigate the impact of the molecular
architecture of the copolymers on luminescence proper-
ties, we compared the emission spectra of the diols 1a
and 2a with those of the respective copolymers 1b-P S,
1c-P S, and 2c-P S. We observed that the overall spectra
of the copolymers are blue-shifted (5-25 nm) and much
narrower than one of the diols (Figure 7). This would
probably indicate that the intermolecular interactions
between chromophores due to the formation of ag-
gregates15 are diminished. A more detailed study of the
luminescence of these copolymers is in progress.
F igu r e 2. 1H NMR spectra in CDCl3 at room temperature
(top) of copolymer 1b-P S 4 and (bottom) of polystyrene (Mn )
6500, PDI ) 1.51) obtained through ATRP using R,R′-dibromo-
p-xylene as an initiator.
zation of styrene and ethyl acrylate. While in the case
of styrene all of the initiator was consumed, the ef-
ficiency of initiation of the polymerization of ethyl
acrylate was very low. The CC triple bonds of the rod
block do not interfere with the polymerization. The
combination of PMDETA/CuBr turned out to give
polymers with higher molecular weight than the com-
bination bipy/CuBr. Since the obtained polydispersities
are somewhat broad, this polymerization method allows
mainly to control the shape and the type of the blocks
of the copolymers.
Con clu sion s
Exp er im en ta l Section
OligoPPEs carrying 2-halogenopropionyloxy or 4-(bro-
momethyl)benzyloxy as ATRP active functionalities
were prepared and used as initiators in the polymeri-
P h ysica l Ch a r a cter iza tion . The NMR spectra were ob-
tained at 300 or 400 MHz in CDCl3 at room temperature. For
signal assignment the carbon multiplicity [quaternary (q-C),

Macromolecules, Vol. 35, No. 15, 2002
Rod-Coil Block Copolymer 5761
F igu r e 5. SEC chromatograms detected at 254 nm (s) and
350 nm (- - -) of the product obtained through ATRP polym-
erization of styrene in the presence of 1d . Reaction condi-
tions: R,R′-dichloro-p-xylene as the initiator, CuBr, bipyridine,
diphenyl ether, 130 °C. Mn ) 13 600, Mw ) 20 200, PDI ) 1.48.
F igu r e 3. SEC chromatograms of (a) copolymer 1b-P S 1 (s)
and the initiator 1b (- - -) and (b) copolymer 1c-P S 2 (s) and
initiator 1c (- - -).
F igu r e 6. Absorption spectrum of 1c-P S (s) and fluorescence
spectra of 1b-P S (- - -), 1c-P S (‚‚‚), and 2c-P S (-‚‚-) copolymers
dissolved in CHCl3. Excitation wavelengths were 340 nm (1b-
P S and 1c-P S) and 370 nm (2c-P S).
F igu r e 4. Micro-Raman spectrum of 1b-P S copolymer film
cast on a KBr disk and irradiated with a linearly polarized
monochromatic radiation at 514.5 nm.
tertiary (CH), secondary (CH2), primary (CH3)] was determined
with DEPT-135 experiments. Molecular weights (Mn and Mw)
were determined through gel permeation chromatography
(Ultrastyragel columns with 500 and 104 Å pore size; THF was
distilled from sodium/benzophenone and samples were passed
through a 0.5 µm Millipore filter; 1 mL/min flow; room
temperature) using polystyrene standards for calibration.
Ma ter ia ls. Compounds 1a and 2a were synthesized accord-
ing to known procedures.7b Styrene and ethyl acrylate (Merck)
were vacuum-distilled from finely powdered calcium hydride.
Methylene chloride was washed with concentrated sulfuric acid
and then with dilute sodium hydroxide and finally with water,
dried over sodium hydroxide and calcium chloride pellets, and
F igu r e 7. Fluorescence spectra of 1c-P S 1 (s) and 1a (‚‚‚) as
thin films cast from CHCl3. Excitation wavelength was 330
nm.
fractionally distilled. Diphenyl ether (Merck) was stored over
molecular sieves (4 Å) and purged with argon for 30 min before
the polymerization was started. CuBr (Aldrich), 2,2′-bipyridine
(bipy, Merck), N,N,N′,N′,N′′-pentamethyldiethylenetriamine
(PMDETA, Aldrich), and all the other reagents and solvents
were used as received. All reactions were run under an inert
atmosphere (N2, Ar). Silica gel 60 (Merck, 0.082-0.2 mm) was
used as the stationary phase for column chromatography.

5762 Tsolakis et al.
Macromolecules, Vol. 35, No. 15, 2002
P r ep a r a tion of th e In itia tor s. In itia tor 1b. To a cooled
(ice bath) solution of 1a (125 mg, 0.26 mmol) and Et3N (75
µL, 0.54 mmol) in CH2Cl2 (20 mL) was added 2-chloropropionyl
chloride (280 µL, 2.9 mmol). The reaction mixture was stirred
for 1 h at 0 °C and for a further 12 h at room temperature.
The red solution was condensed by evaporation of most of the
solvent. Ethanol (20 mL) was added to the residue, and the
colorless precipitate was isolated, washed with ethanol, and
dried under vacuum. Column chromatography (toluene) gave
1b (145 mg, 85%) as a colorless solid; mp 117-118 °C. 1H
NMR: δ ) 0.88 (m, 6H), 1.2-1.5 (m, 12H), 1.69 (m, 4H), 1.83
(d, J ) 7.0 Hz, 6H), 2.80 (m, 4H), 4.62 (q, J ) 7.0 Hz, 2H),
7.14 (half of AA′XX′, 4H), 7.36 (s, 2H), 7.55 (half of AA′XX′,
4H). 13C NMR: δ ) 14.3 (CH3), 21.3 (CH3), 22.6 (CH2), 29.2
(CH2), 30.6 (CH2), 31.7 (CH2), 34.1 (CH2), 52.2 (CH), 88.8 (q-
C), 92.9 (q-C), 121.3 (CH), 121.7 (q-C), 122.4 (q-C), 132.3 (CH),
132.7 (CH), 142.3 (q-C), 150.1 (q-C), 168.3 (q-C). C40H44O4Cl2
(659.694): calcd C, 72.83; H, 6.72; found C, 72.96; H, 6.82.
In itia tor 1e. Following the procedure given for the prepa-
ration of 1b, monofuntional initiator 1e (108 mg, 68%) was
obtained through the reaction of 1a (125 mg, 0.26 mmol) with
2-bromopropionyl chloride (30 µL, 0.29 mmol) and Et3N (75
µL, 0.54 mmol) in CH2Cl2 (20 mL) as a colorless solid; mp 75-
ture, THF (2-4 mL) was added to dissolve the polymer. The
suspension was filtered for removing most of the catalyst.
Styrene copolymers were precipitated through the addition of
methanol (20-fold excess by volume). Ethyl acrylate copolymers
were precipitated by pouring the filtered solution into a
mixture of methanol and water (50:50 v/v; 20-fold excess by
volume). The precipitated ethyl acrylate copolymers were
dissolved in diethyl ether. The solution was extracted with
plenty of water, and diethyl ether was evaporated to give the
ethyl acrylate copolymers.
Ack n ow led gm en t. This work was supported by the
Operational Program for Education and Initial Voca-
tional Training on “Polymer Science and Technology”-
3.2a, 33H6, administered through the Ministry of
Education and Religious Affairs in Greece.
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77 °C. H NMR: δ ) 0.89 (m, 6H), 1.2-1.5 (m, 12H), 1.71 (m,
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(14) Weder, C.; Wrighton, M. S. Macromolecules 1996, 29, 5157.
(15) (a) Halkyard, C. E.; Rampey, M. E.; Kloppenburg, L.; Studer-
Martinez, S. L.; Bunz, U. H. F. Macromolecules 1998, 31,
8655. (b) Fiesel, R.; Halkyard, C. E.; Rampey, M. E.; Klop-
penburg, L.; Studer-Martinez, S. L.; Scherf, U.; Bunz, U. H.
F. Macromol. Rapid Commun. 1999, 20, 107. (c) Miteva, T.;
Palmer, L.; Kloppenburg, L.; Neher, D.; Bunz, U. H. F.
Macromolecules 2000, 33, 652. (d) Levitus, M.; Schmieder,
K.; Ricks, H.; Shimizu, K. D.; Bunz, U. H. F.; Garcia-Garibay,
M. A. J . Am. Chem. Soc. 2001, 123, 4259.
In itia tor 1c. A solution of 1a (150 mg, 0.31 mmol) in
acetone (10 mL) was added dropwise to a mixture of R,R′-
dibromo-p-xylene (820 mg, 3.1 mmol) of K2CO3 (47 mg, 0.34
mmol) in acetone (15 mL). The reaction mixture was refluxed
for 24 h. Most of the solvent was removed by evaporation.
Through the addition of methanol (20 mL) the crude product
was precipitated. The solid was isolated, washed well with of
water and methanol, and then dispersed in a 10-fold excess
by volume of hot methanol (60 °C), and the mixture was stirred
for 12 h at 60 °C. The solid was isolated and finally purified
with column chromatography (toluene/hexane 1:1 v/v) to give
1c (196 mg, 75%) as a colorless solid; mp 148-150 °C. 1H NMR:
δ ) 0.88 (m, 6H), 1.2-1.5 (m, 12H), 1.69 (m, 4H), 2.78 (m,
4H), 4.50 (s, 4H) 5.08 (s, 4H), 6.94 (half of AA′XX′, 4H), 7.33
(s, 2H), 7.41 (s, 8H), 7.46 (half of AA′XX′, 4H). 13C NMR: δ )
14.1 (CH3), 22.6 (CH2), 29.2 (CH2), 30.6 (CH2), 31.7 (CH2), 33.0
(CH2), 34.1 (CH2), 69.5 (CH2), 87.4 (q-C), 93.7 (q-C), 114.9 (CH),
116.1 (q-C), 122.5 (q-C), 127.8 (CH), 129.3 (CH), 132.1 (CH),
132.9 (CH), 136.9 (q-C), 137.6 (q-C), 142.0 (q-C), 158.6 (q-C).
In itia tor 2c. Compound 2c was prepared according to the
procedure given for 1c, using a solution of 2a (240 mg, 0.31
mmol) in acetone (10 mL) and a mixture of R,R′-dibromo-p-
xylene (820 mg, 3.1 mmol) and K2CO3 (47 mg, 0.34 mmol) in
acetone (15 mL). Column chromatography (toluene/ethyl ac-
etate 4:1 v/v) gave 2c (254 mg, 72%) as a colorless solid; mp
1
124-126 °C. H NMR: δ ) 0.88 (m, 12H), 1.2-1.5 (m, 24H),
1.66 (m, 8H), 2.76 (m, 8H), 4.50 (s, 4H) 5.08 (s, 4H), 6.94 (half
of AA′XX′, 4H), 7.32 (s, 2H), 7.36 (s, 2H), 7.41 (s, 8H), 7.45
(half of AA′XX′, 4H). 13C NMR: δ ) 14.09 (CH3), 14.11 (CH3),
22.6 (CH2), 29.0-34.1 (9 signals, CH2), 69.6 (CH2), 78.2 (q-C),
81.7 (q-C), 87.2 (q-C), 94.6 (q-C), 115.0 (CH), 115.9 (q-C), 120.8
(q-C), 123.8 (q-C), 127.8 (CH), 129.3 (CH), 132.1 (CH), 133.0
(CH), 133.3 (CH), 136.9 (q-C), 137.7 (q-C), 142.0 (q-C), 143.6
(q-C), 158.7 (q-C).
ATRP of Styr en e a n d Eth yl Acr yla te Usin g th e Rigid
Ma cr oin itia tor s. A mixture of the initiator (0.1 mmol), CuBr
(0.2 mmol), and bipyridine (0.6 mmol) or N,N,N′,N′,N′′-
pentamethyldiethylenetriamine (0.2 mmol) was degassed.
Diphenyl ether (if used) and the monomer were added via a
syringe. The reaction mixture was heated (temperatures are
specified in Table 1) for 12 h. After cooling to room tempera-
MA020256K