Tandem type polymerization. Synthesis and characterization of ordered poly(amide-thioether) from 2,6-dichlorophenyl methacrylate, 4,4′-thiobis(benznenethiol), and 4,4′-oxydianiline

Article abstract of DOI:10.1021/ma025712j

Ordered poly(amide-thioether) (17) was prepared by tandem type polymerization of 2,4-dichlorophenyl acrylate (11), 4,4′-thiobis(benznenthiol) (12), and 4,4′-oxydianiline (16). The polymerization was carried out by mixing all monomers in the presence of catalytic amounts of triethylamine (TEA) and 1-hydroxybenzotriazole (HOBt) in 1-methyl-2-pyrrolidinone (NMP) at 20 °C for 2 h and then 80 °C for 2 days, yielding polymer 17 with a number-average molecular weight (M_n) of 25 000. Authentic ordered poly(amide-thioether) (18) was prepared to verify the structure of polymer 17. The microstructure of polymers obtained was investigated by ¹H and ¹³C NMR spectroscopy, and it has been found the polymer obtained has the expected ordered structure. Furthermore, model reactions were studied in detail to demonstrate the feasibility of ordered polymer formation.

Full text of DOI:10.1021/ma025712j

Macromolecules 2003, 36, 1815-1818
1815
Tandem Type Polymerization. Synthesis and Characterization of
Ordered Poly(amide-thioether) from 2,6-Dichlorophenyl Methacrylate,
4,4′-Thiobis(benznenethiol), and 4,4′-Oxydianiline
Kou su k e Tsu ch iya , Yu ji Sh iba sa k i, a n d Mitsu r u Ued a *
Department of Organic and Polymeric Materials, Graduate School of Science and Engineering,
Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, J apan
Received October 5, 2002; Revised Manuscript Received J anuary 9, 2003
ABSTRACT: Ordered poly(amide-thioether) (17) was prepared by tandem type polymerization of 2,4-
dichlorophenyl acrylate (11), 4,4′-thiobis(benznenthiol) (12), and 4,4′-oxydianiline (16). The polymerization
was carried out by mixing all monomers in the presence of catalytic amounts of triethylamine (TEA) and
1-hydroxybenzotriazole (HOBt) in 1-methyl-2-pyrrolidinone (NMP) at 20 °C for 2 h and then 80 °C for 2
days, yielding polymer 17 with a number-average molecular weight (Mn) of 25 000. Authentic ordered
poly(amide-thioether) (18) was prepared to verify the structure of polymer 17. The microstructure of
polymers obtained was investigated by 1H and 13C NMR spectroscopy, and it has been found the polymer
obtained has the expected ordered structure. Furthermore, model reactions were studied in detail to
demonstrate the feasibility of ordered polymer formation.
In tr od u ction
We have been interested in the synthesis of ordered
polymers by polycondensation and developed the method
of sequence control in one-step polycondensation.8-10
Tandem reactions will provide us another synthetic
route to prepare ordered polymers. Conjugated esters
are less reactive than saturated esters in nucleophilic
substitution, because the former lose a certain amount
of resonance energy when they are converted to addition
products. This difference in their reactivity can be used
for the synthesis of condensation polymers using tan-
dem reactions. The facile addition of nucleophiles to
double bonds activated by electron-withdrawing groups
is well-known, and the Michael-type polyaddition of
diamines, dithiols, and carbanions has been extensively
studied.11 Thus, we decided to study the preparation of
ordered polymers from R,â-unsaturated esters, dithiols,
and diamines using a class of tandem reactions where
one of the reactions is addition and the other is
condensation. The Michael-type polyaddition of dithiols
to R,â-unsaturated esters produces saturated esters,
whose enhanced reactivity promotes the reaction with
diamines to produce ordered poly(amide-thioether)s.
This article describes a successful synthesis of ordered
poly(amide-thioether) (17) by tandem type polymeri-
zation of 2,4-dichlorophenyl acrylate (11), 4,4′-thiobis-
(benzenethiol) (12), and 4,4′-oxidianiline (16).
The combination of several reactions in single opera-
tion, which is called a tandem reaction,1 is a powerful
means to enhance synthetic efficiency and has been
widely applied in polymer chemistry. The modification
of a polymer after its polymerization in a single opera-
tion is a typical example of a tandem type polymeriza-
tion. For instance, Wagener et al. reported a tandem
homogeneous metathesis/heterogeneous hydrogenation
procedure, which consists of using a ruthenium complex
to first drive homogeneous metathesis of dienes and
then to promote heterogeneous hydrogenation.2 Grubbs
et al. also reported that a single ruthenium catalyst
mediates three mechanically distinct reactions: the
ring-opening metathesis polymerization of 1,5-cyclo-
octadiene, the atom-transfer radical polymerization of
methyl methacrylate, and hydrogenation of the result-
ing copolymers in a single-step operation.3 Furthermore,
a new synthetic route to polybenzoxazole via tandem
Claisen rearrangement was reported by Hiratani et al.,
where the tandem Claisen rearrangement of polyamide
containing isobutenyl bis(aryl ether) moieties gives
hydroxyl groups ortho to the amide groups, and then
sequential intramolecular cyclization leads to the poly-
benzoxazole.4
The monomer transformation-polymerization is an-
other example of tandem type polymerization. Crivello
et al. reported the synthesis of poly(vinyl ether) by a
tandem isomerization-cationic polymerization tech-
nique using allylic ethers.5 Swager et al. reported the
synthesis of poly(naphthodithiophene)s via tandem cy-
clization-polymerizations to produce aromatized mono-
mers in situ prior to oxidative polymerization.6 The step
growth polymerization via tandem ene and Diels-Alder
reactions was demonstrated by Stadler et al., where the
regiochemistry of the Diels-Alder reaction could be
controlled by the solvent polarity.7
Exp er im en ta l Section
Ma ter ia ls. 1-Methyl-2-pyrrolidinone (NMP) was distilled
from CaH2 under reduced pressure and stored over 4-A
molecular sieves. p-Nitrophenyl acrylate (1) and p-nitrophenyl
methacrylate (2) were prepared according to the reported
procedure.12 4,4′-Thiobis(benzenethiol) (12) and 4,4′-oxydi-
aniline (16) were recrystallized from toluene/methanol and
tetrahydrofuran, respectively. Triethylamine (TEA) was dis-
tilled from KOH and stored over KOH. Other reagents and
solvents were used as received.
2,4-Dich lor op h en yl Acr yla te (11). To an ice-cooled solu-
tion of 2,4-dichlorophenol (17 g, 100 mmol) and TEA (13.8 mL,
100 mmol) in THF (40 mL) was added dropwise acryloyl
chloride (8.5 mL, 105 mmol) at 0 °C. After being stirred for 1
h, TEA‚HCl was filtered and the solution was evaporated. The
product was purified by distillation at 60-61 °C/1.5 mmHg.
* To whom all the correspondence should be addressed:
telephone
u.polymer.titech.ac.jp.
and
fax
+81-3-5734-2127; e-mail mueda@
10.1021/ma025712j CCC: $25.00 © 2003 American Chemical Society
Published on Web 02/27/2003

1816 Tsuchiya et al.
Macromolecules, Vol. 36, No. 6, 2003
1
The yield was 9.8 g (45%). IR (NaCl): ν 1751 cm-1 (CdO). H
NMR (CDCl3): δ 6.08 (1H, dd), 6.34 (1H, dd), 6.67 (1H, dd),
and 7.13 (1H, d), 7.27 (1H, dd), 7.46 ppm (1H, d). Anal. Calcd
for C9H6Cl2O2: C, 49.80%; H, 2.79%; Cl, 32.67%. Found: C,
49.88%; H, 2.94%; Cl, 32.83%.
Sch em e 1
Mod el Com p ou n d s. p-Nitr op h en yl 3-P h en ylth iop r o-
p ion a te (5). Benzenethiol (3) (0.1 mL, 1.0 mmol) was added
to a solution of 1′ (0.207 g, 1.0 mmol) and TEA (0.003 mL) in
NMP (2 mL) at room temperature. The solution was stirred
for 2 h and poured into 3 wt % aqueous sodium hydrogen
carbonate (50 mL). The precipitate was filtered, washed with
water, and dried. The yield was 0.275 g (91%). The product
was purified by silica gel chromatography using ethyl acetate/
n-hexane (2:3). IR (KBr): ν 1766 cm-1 (CdO). 1H NMR
(CDCl3): δ 2.91 (2H, t), 3.28 (2H, t), 7.30 (5H, m), and 7.43
(2H, m), 8.26 ppm (2H, d). Anal. Calcd for C15H13NO4S: C,
59.39%; H, 4.32%; N, 4.62%; S, 10.57%. Found: C, 59.62%; H,
4.33%; N, 4.69%; S, 10.48%.
Rea ction of 11 w ith 4-P h en oxya n ilin e. A solution of 11
(0.109 g, 0.5 mmol), 4-phenoxyaniline (0.0926 g, 0.5 mmol),
TEA (0.03 mL), 1-hydroxybenztriazole (HOBt) (0.004 g, 5 mol
%), and p-tert-butylanisole (0.016 g 1.0 mmol) as an internal
standard in NMP (2 mL) was stirred at 20 °C. The yield of
N-(4-phenoxyphenyl)acrylamide (14) was determined by the
integration ratio between phenyl protons (7.47 ppm) of 14 and
butyl protons (1.3 ppm) of p-tert-butylanisole in a 1H NMR
spectrum.
Rea ction of 2, 4-Dich lor op h en yl Aceta te w ith 4-P h en -
oxya n ilin e. This reaction was carried out as described above.
3,3′-[4,4′-Th iobis(p h en ylen eth io)]bis(2,4-d ich lor op h en -
yl p r op ion a te) (13). A solution of 11 (0.434 g, 2.0 mmol), 12
(0.251 g, 1.0 mmol), and TEA (0.003 mL) in NMP (2.0 mL)
was stirred at room temperature for 1 h and poured into 3 wt
% aqueous sodium hydrogen carbonate (50 mL). The solution
was extracted with dichloromethane. The extract was dried
over MgSO4 and evaporated. The residue was subjected to
silica gel column chromatography using dichloromethane as
an eluent to give a yellow liquid. The yield was 0.64 g (94%).
gel permeation chromatograph (GPC) with polystyrene cali-
bration using Tosoh HLC-8120GPC equipped with consecutive
TSK gel columns GMHHR-M and GMHHR-L at 40 °C in DMF
containing 0.01 mol/L LiBr. Wide-angle X-ray measurements
were performed using Rigaku-Denki RU-200 BH with Ni-
filtered Cu KR radiation.
1
IR (NaCl): ν 1778 cm-1(CdO). H NMR (CDCl3): δ 2.92 (4H,
t), 3.27 (4H, t), 7.05 (2H, d), 7.29 (10H, m), and 7.43 ppm (2H,
d). Anal. Calcd for C30H22Cl4O4S3: C, 52.64%; H, 3.24%; S,
14.05%; Cl, 20.72%. Found: C, 52.54%; H, 3.16%; S, 14.41%;
Cl, 20.90%.
Resu lts a n d Discu ssion
Syn t h esis of Or d er ed P oly(a m id e-t h ioet h er ) (17).
Compound 11 (0.217 g, 1.0 mmol), 12 (0.125 g, 0.5 mmol), and
16 (0.1 g, 0.5 mmol) were dissolved in NMP (1.4 mL). To this
solution was added TEA (0.003 mL) and HOBt (0.008 g, 0.05
mmol). The solution was stirred at room temperature for 2 h
and then at 80 °C for 2 days. The resulting viscous solution
was poured into methanol (50 mL). The polymer was filtered
off and dried at 80 °C in vacuo for 24 h. The yield was 0.27 g
(97%). Number- and weight-average molecular weights (Mn
and Mw) were 25 000 and 44 000, respectively. IR (KBr): ν
3135 (aromatic C-H), 2927 (aliphatic C-H), 1658 (CdO), 1218
Design of r,â-Un sa tu r a ted Ester s. The choice of
R,â-unsaturated esters is most important in the prepa-
ration of an ordered poly(amide-thioether) by tandem
consecutive reactions, the Michael addition, and ami-
nolysis. First, p-nitrophenyl acrylate (1) and p-nitro-
phenyl methacrylate (2) were selected as R,â-unsatur-
ated esters, where acrylate and active ester units are
responsible for the Michael addition and aminolysis,
respectively.
Addition reactions of 1 or 2 with benzenethiol (3) or
p-nitrobenzenethiol (4) were carried out in the presence
of catalytic amounts of TEA in NMP at 20 °C. The
reaction was monitored by taking the NMR spectrum
of a drop from the reaction mixture at different times
(Scheme 1). Compounds 1 and 2 disappeared in 2 h.
The molar ratio of an adduct, p-nitrophenyl 3-phenyl-
thiopropanoate (5), and a substitution product, S-p-
phenyl propenethioate (6), was 91:9 in the reaction of 1
with 3. On the other hand, 2 reacted slowly with 3 and
gave p-nitrophenyl 3-phenylthio-2-methylpropenoate (7)
(58 mol %) and S-p-phenyl 2-methylpropanethioate (8)
(42 mol %). The use of 4 in the model reaction gave
better yield of the addition product 9 in 80 mol %, but
the formation of S-p-nitrophenyl 2-methylpropenethio-
ate (10) was still observed.
1
cm-1 (C-O-C), 813 (C-S-C). H NMR (CDCl3): δ 2.64 (4H,
t), 3.23 (4H, t), 6.90 (4H, d), 7.30 (8H, dd), and 7.53 ppm (4H,
d). 13C NMR (CDCl3): δ 29.20, 36.97, 119.49, 121.86, 130.19,
132.28, 133.02, 135.47, 136.74, 153.56, 169.65 ppm. Anal.
Calcd for (C30H26N2O3S3): C, 64.49%; H, 4.60%; N, 5.01%; S,
17.22%. Found: C, 64.45%; H, 5.07%; N, 5.17%; S, 17.00%.
Au th en tic Or d er ed P oly(a m id e-th ioeth er ) (18). Com-
pound 13 was prepared from 11 and 12 as described above.
The solution of 13 (0.54 g, 0.5 mmol) and 16 (0.1 g, 0.5 mmol)
was dissolved in NMP (1.4 mL) was stirred 80 °C for 2 days.
The polymer was isolated as described above. The yield was
0.273 g (98%). The Mn and Mw were 19 000 and 36 000,
respectively. Anal. Calcd for (C30H26N2O3S3): C, 64.49%; H,
4.60%; N, 5.01%; S, 17.22%. Found: C, 63.77%; H, 4.80%; N,
5.09%; S, 16.93%.
Mea su r em en t. The infrared spectra were recorded on a
Horiba FT-210 spectrophotometer. 1H and 13C NMR spectra
were recorded on a Bruker GPX300 (300 MHz) spectrometer.
Thermal analyses were performed on a Seiko thermal analyzer
at a heating rate of 10 and 5 °C/min for thermogravimetry
(TG) and differential scanning calorimetry (DSC) under ni-
trogen, respectively. Molecular weights were determined by a
To suppress the substitution reaction, a less reactive
ester than p-nitrophenyl ester, 2,4-dichlorophenyl acry-
late (11), was prepared from acryloyl chloride and 2,4-
dichlorophenol. The reaction of 11 with 4,4′-thiobis-

Macromolecules, Vol. 36, No. 6, 2003
Tandem Type Polymerization 1817
Sch em e 2
Sch em e 3
F igu r e 1. 13C NMR spectra of (a) polymer 17 and (b) polymer
18 in DMSO-d6 at 60 °C.
Sch em e 4
Ta ble 1. Rea ction of Mon om er 11 a n d 2,4-Dich lor op h en yl
Aceta te w ith 4-P h en oxya n ilin e
yield (%)
run
temp (°C)
time (h)
14
15
1
2
3
4
5
20
20
60
80
80
1
18
0.5
0.5
2
8
18
10
27
40
16
80
55
77
99
Sch em e 5
a
Reaction was carried out with 1.0 mmol of each compound in
the solvent at room temperature for 4 h. Determined by 1H NMR
b
spectroscopy.
(benznenthiol) (12) was performed in the presence of
catalytic amounts of TEA in NMP at 20 °C. The desired
addition product, 3,3′-[4,4′-thiobis(phenylenethio)]bis-
(2,4-dichlorophenyl propionate) (13), was obtained in
quantitative yield in 30 min. Furthermore, no substitu-
tion product was observed (Scheme 2).
To investigate the difference of reactivity between
conjugated esters and saturated esters, the reaction of
11 and 2,4-dichlorophenyl acetate with 4-phenoxy-
aniline was carried out in NMP in the presence of
1-hydroxybenzotriazole (HOBt) that is an extremely
efficient catalyst in the aminolysis of active 4-nitro-
phenyl and trichlorophenyl esters (Scheme 3).13
The yields of N-(4-phenoxyphenyl)acrylamide (14) and
N-(4-phenoxyphenyl)acetamide (15) were determined by
the integration ratios between phenyl protons of 14 (7.47
ppm) and those of 15 (7.55 ppm) with butyl protons (1.3
ppm) of p-tert-butylanisole as an internal standard in
1H NMR spectra. The results summarized in Table 1
indicated that 2,4-dichlorophenyl acetate is about 5
times more reactive than 11 at 60 °C in 30 min. The
Michael addition converts unsaturated esters to satu-
rated esters, leading to a facial aminolysis.
following three monomers, 11, 12, and 4,4′-oxydianiline
(16) for the preparation of ordered poly(amide-thio-
ether) (17). The polymerization was carried out by using
a direct procedure (Scheme 4).
The solution of 11, 12, and 16 in the presence of TEA
and HOBt in NMP was stirred at 20 °C for 2 h and then
80 °C for 2 days. The polymerization involves the
following two steps: (i) the Michael addition of 12 to
11, i.e., generation of the diester with the enhanced
reactivity, (ii) condensation of the diester with the
diamine. The polymerization proceeded in homogeneous
solution and gave polymer with a number-average
molecular weight of 25 000 (relative to polystyrene
standards by GPC in DMF).
Syn th esis of Au th en tic Or d er ed P oly(a m id e-
th ioeth er ). Authentic ordered polymer (18) was syn-
thesized for the characterization of the structure of
ordered polymer 17 obtained by tandem polymerization.
Authentic polymer 18 was prepared as shown in Scheme
5.
P olym er Syn th esis. Syn th esis of Or d er ed P oly-
(a m id e-th ioeth er ) by Ta n d em P olym er iza tion . On
the basis of these model reactions, we decided to use

1818 Tsuchiya et al.
Macromolecules, Vol. 36, No. 6, 2003
poly(addition-condensation) of 11, 12, and 16 produced
the desired ordered poly(amide-thioether) 17.
Polymers 17 and 18 were white solids, soluble in
sulfuric acid, methanesulfonic acid, and NMP at room
temperature. A transparent film was cast from a solu-
tion of polymer 17 in NMP.
The thermal stability of polymer 17 was examined by
thermogravimetry (TG). The polymer showed a 10%
weight loss at 350 °C. The DSC trace of the first-heating
process for polymer 17 illustrated in Figure 2 showed a
bimodal endothermic peak appeared at 265 and 297 °C.
When as-synthesized polymer was annealing at 270 °C
for 1 h, the sample exhibited a unimodal trace, and the
endothermic peak became comparatively sharp. It sug-
gested that the recrystallization took place during the
annealing process. Thus, the lower endothermic peak
could be assigned to submelting due to the thin and
thermodynamically unstable crystallinities.
F igu r e 2. DSC profiles of (a) as-made polymer 17 and (b)
polymer 17 after annealing at 270 °C for 1 h.
WAXD diffraction patterns of as-made and annealed
polymers are illustrated in Figure 3. Well-defined sharp
rings were observed on the annealing treatment poly-
mer. It was another evidence for recrystallization. These
results agreed with those of DSC.
Con clu sion s
We have demonstrated that the synthesis of ordered
poly(amide-thioether) can be achieved by tandem po-
lymerization of 11, 12, and 16 in the presence of TEA
and HOBt in NMP. Thus, tandem reaction proves highly
suitable to the preparation of ordered polymers. We are
currently extending tandem reaction to the synthesis
of other condensation polymers.
Ack n ow led gm en t. We acknowledge the help from
Dr. Masatoshi Tokita (Department of Organic and
Polymeric Materials, Graduate School of Science and
Engineering, Tokyo Institute of Technology) with the
WAXD measurement. This study was financially sup-
ported by the New Energy and Industrial Technology
Development Organization (NEDO) for the project on
Technology for Nanomaterials.
Refer en ces a n d Notes
(1) Parsons, P. J .; Penkett, C. S.; Shell, A. J . Chem. Rev. 1996,
96, 195.
(2) Watson, M. D.; Wagener, K. B. Macromolecules 2000, 33,
3196.
(3) Louie, J .; Bielawski, C. W.; Grubbs, R. H. J . Am. Chem. Soc.
2000, 122, 12872.
F igu r e 3. X-ray diffraction of (a) as-made polymer 17 and
(b) polymer 17 after annealing at 270 °C for 1 h.
(4) Yang, G.; Matsuzono, S.; Koyama, E.; Tokuhisa, H.; Hiratani,
K. Macromolecules 2001, 34, 6545.
(5) Crivello, J . V.; Rajaraman, S. K. J . Polym. Sci., Part A:
Polym. Chem. 1999, 37, 687. (b) Crivello, J . V.; Rajamaran,
S. K. Macromol. Symp. 1998, 132, 37.
(6) Tovar, J . D.; Swager, T. M. Adv. Mater. 2001, 13, 1775.
(7) Mallakpour, S. E.; Kolshorn, H.; Schollmeyer, D.; Stadler, R.
Macromol. Chem. Phys. 1997, 198, 251.
(8) Ueda, M. Prog. Polym. Sci. 1999, 24, 699.
(9) Li, L.; Yonetake, K.; Ueda, M. Makromol. Chem. Phys. 2001,
202, 1531.
Compound 13 was prepared from 11 and 12, and then
the solution polycondensation of 13 with 16 was carried
out in the presence of HOBt in NMP, giving poly-
(amide-thioether) 18 with a number-average molecular
weight of 20 000.
P olym er Ch ar acter ization . All the polymers showed
characteristic NH, amide I, amide II, and thioether
bands in the ranges 3274, 1658, 1542, and 1218 cm-1
,
respectively. Elementary analysis also supported the
formation of the expected polymers.
(10) Hikita, T.; Mochizuki, A.; Takeuchi, K.; Asai, M.; Ueda, M.
Macromolecules 2002, 35, 6202.
The microstructure of the polymers determined by 1H
1
(11) Smith, M. B.; March, J . In Advanced Organic Chemistry;
Wiley-Interscience: New York, 2001; p 975.
(12) Ueda, M.; Okada, T. In Step-Growth Polymers for High-
Performance Materials; Hedrick, J . L., Labadie, J . W., Eds.;
ACS Symposium Series 624; American Chemical Society:
Washington, DC, 1996; p 442.
and 13C NMR spectroscopy. All peaks in the H NMR
spectra of authentic polymer 17 and polymer 18 were
well assigned, and the spectra of polymers 17 and 18
were identical.
The 13C NMR spectra of polymers 17 and 18 with the
assignment of each resonance are presented in Figure
1. The spectrum of polymer 18 is identical to that of
polymer 17. These findings clearly indicate that direct
(13) Ueda, M.; Sato, A.; Imai, Y. J . Polym. Sci., Polym. Chem.
1979, 17, 783.
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