Mild incorporation of CO2 into epoxides: Application to nonisocyanate synthesis of poly(hydroxyurethane) containing triazole segment by polyaddition of novel bifunctional five-membered cyclic carbonate and diamines

Article abstract of DOI:10.1002/pola.28967

The cyclic amidinium iodide effectively catalyzed the ring-expansion addition of epoxides with carbon dioxide under ordinary pressure and mild conditions to obtain the corresponding five-membered cyclic carbonates in high yield. The novel triazole-linked bifunctional five-membered cyclic carbonate was synthesized successfully by the click reaction of the azide- and the alkyne-substituted five-membered cyclic carbonates under ambient temperature in high yield. The chemical structure of the novel bis(cyclic carbonate) was characterized by one- and two-dimensional nuclear magnetic resonance spectra. The obtained bis(cyclic carbonate) was converted with commercially available diamines to poly(hydroxyurethane) containing triazole segment without catalyst in high yield. Analyses of the resulting poly(hydroxyurethane)s were performed by proton nuclear magnetic resonance, size exclusion chromatography, thermogravimetric analysis, and differential scanning calorimetry.

Full text of DOI:10.1002/pola.28967

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Mild Incorporation of CO2 into Epoxides: Application to Nonisocyanate
Synthesis of Poly(Hydroxyurethane) Containing Triazole Segment
by Polyaddition of Novel Bifunctional Five-Membered Cyclic Carbonate
and Diamines
1
Naoto Aoyagi,1 Yoshio Furusho,1,2 Takeshi Endo
1Molecular Engineering Institute, Kindai University, 11-6 Kayanomori, Iizuka, Fukuoka 820-8555, Japan
2Department of Chemistry, Shiga University of Medical Science, Seta, Otsu 520-2192, Japan
Correspondence to: T. Endo (E-mail: tendo@moleng.fuk.kindai.ac.jp)
Received 27 November 2017; accepted 17 January 2018; published online 00 Month 2018
DOI: 10.1002/pola.28967
ABSTRACT: The cyclic amidinium iodide effectively catalyzed
the ring-expansion addition of epoxides with carbon dioxide
under ordinary pressure and mild conditions to obtain the cor-
responding five-membered cyclic carbonates in high yield. The
novel triazole-linked bifunctional five-membered cyclic carbon-
ate was synthesized successfully by the click reaction of the
azide- and the alkyne-substituted five-membered cyclic carbo-
nates under ambient temperature in high yield. The chemical
structure of the novel bis(cyclic carbonate) was characterized
by one- and two-dimensional nuclear magnetic resonance
spectra. The obtained bis(cyclic carbonate) was converted with
commercially available diamines to poly(hydroxyurethane)
containing triazole segment without catalyst in high yield.
Analyses of the resulting poly(hydroxyurethane)s were per-
formed by proton nuclear magnetic resonance, size exclusion
chromatography, thermogravimetric analysis, and differential
C
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scanning calorimetry.
2018 Wiley Periodicals, Inc. J. Polym.
Sci., Part A: Polym. Chem. 2018, 00, 000–000
KEYWORDS: click reaction; CO2; epoxide; five-membered cyclic
carbonate; poly(hydroxyurethane)
results in improved water resistance as well as flexibility,
which suggest potential applications as soft adhesives and
additives.19 The ion gels that have hydroxyurethane cross-
linking points show high ionic conductivities due to their
high compatibility with ionic liquids.20 Several other poly(hy-
droxyurethane)s are used as polymer/liquid crystal compos-
ite films,21 amphiphilic antibacterial polymers,22 and dye
fixation agent.23 Accordingly, synthetic chemists have devel-
oped a wide range of CO2 incorporation reactions for the
synthesis of cyclic carbonates.2,24–28 However, most of these
reactions require some pressure (ꢀ20 atm) and/or high
temperature unless expensive metal catalysts are
employed.29 We have recently reported that the cyclic amidi-
nium salts such as 1,8-diazabicyclo[5.4.0]-7-undecene hydro-
iodide (DBU•HI) effectively catalyzed the reaction of CO2 and
epoxides under mild conditions such as ordinary pressure
and ambient temperature to obtain the corresponding five-
membered cyclic carbonates in high yield.30 As for bifunc-
tional five-membered cyclic carbonates, they are prepared in
general from commercially available bifunctional epoxides
such as bisphenol A diglycidyl ether,31 resorcinol diglycidyl
INTRODUCTION Carbon dioxide (CO2) is often accused of
being a main culprit of global warming, while in synthetic
chemistry it is regarded as an environmentally friendly
reagent, which is useful especially for phosgene free pro-
cesses.1 Of particular importance is incorporation reaction of
CO2 into epoxides to give five-membered cyclic carbonates,2
which are used in various areas, such as aprotic polar sol-
vents,3 electrolytes,4–6 and lithium ion batteries.7–9 Further-
more, bifunctional five-membered cyclic carbonates can be
converted to poly(hydroxyurethane)s by polyaddition with
a,x-diamines, which provided an alternative route for the
synthesis of polyurethanes without using toxic phosgene or
isocyanates.10–17 Hence, synthesis of functional poly(hydrox-
yurethane)s by nonisocyanate processes have recently
attracted much attention from environmental concerns. For
example, the hydroxyl groups of poly(hydroxyurethane)s can
be utilized as crosslinking points to afford networked poly-
mers.18 Polarities of the networked polymers can be
adjusted by judicious choice of the crosslinkers, which leads
to control over the affinity toward various solvents. Incorpo-
ration of silicon backbones to poly(hydroxyurethane)s
Additional Supporting Information may be found in the online version of this article.
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SCHEME 1 Polyaddition of bifunctional five-membered cyclic carbonate and diamine.
ether,32 ethylene glycol diglycidyl ether,33 butanediol digly-
cidyl ether,32 and so on. The thiol-ene “click” reactions of
dithiol and vinyl-functionalized cyclic carbonate afford the
bifunctional cyclic carbonates in moderate to high yield.34,35
Although the azide-alkyne “click” cycloaddition is one of the
most powerful methods for the synthesis of functional mono-
mers and polymers,36–41 they have not yet been employed
for the synthesis of the bifunctional cyclic carbonates to the
best of our knowledge.
sulfate (>99.0%), spherical silica gel (63–210 mm, neutral),
diethyl ether (>99.0%), hexane (>96.0%), ethyl acetate
(>99.3%), acetone (>99.0%), chloroform (>99.0%), and
acetonitrile (>99.0%) were obtained from Kanto Chemical.
1,2-Bis(2-aminoethoxy)ethane (98%) was obtained from
Aldrich Chemical. 1,8-Diazabicyclo[5.4.0]-7-undecene and N-
ethyldiisopropylamine were dried over CaH2, and then dis-
tilled prior to use. All other reagents were used as received
without further purification.
Herein, we report the nonisocyanate synthesis of poly(hydrox-
yurethane) containing triazole segment using a novel bifunc-
tional five-membered cyclic carbonate and commercially
available a,x-diamines (Scheme 1). The bifunctional cyclic car-
bonate bearing triazole linker was prepared from the cop-
per(I) iodide-catalyzed azide-alkyne click reaction between
cyclic carbonate with azide group and that with alkyne group,
which were synthesized from epibromohydrin or epichlorohy-
drin via CO2 insertion reaction in the presence of a catalytic
amount of DBU•HI under ordinary pressure and mild condi-
tions as a key step. Then, the obtained bifunctional cyclic car-
bonate was converted to poly(hydroxyurethane)s containing
triazole segment in high yield by polyaddition with 1,6-diami-
nohexane or 1,2-bis(2-aminoethoxy)ethane without catalyst.
We also investigated the solubility and thermal properties of
the resulting poly(hydroxyurethane)s.
Characterizations
Proton (1H, 400 MHz), carbon-13 (13C, 100 MHz), distortion-
less enhancement by polarization transfer (DEPT), 1H–1H
correlated spectroscopy (H-H COSY), heteronuclear multiple
quantum coherence (HMQC), and heteronuclear multiple-
bond correlation (HMBC) nuclear magnetic resonance (NMR)
spectroscopy measurements were performed on a JEOL ECS-
400/SS instrument using tetramethylsilane or DMSO-d6 as
an internal standard at 25 8C. The melting points were mea-
sured using an SRS MPA100 automated melting point appa-
ratus and were uncorrected. Mass spectroscopy was
performed on a Shimadzu GCMS-QP5050A in electron ioniza-
tion (EI) mode. Number average molecular weight (Mn) and
polydispersity index (Mw/Mn) were estimated by size exclu-
sion chromatography (SEC) using a TOSOH HLC-8220 GPC
instrument equipped with three consecutive polystyrene gel
columns [TSK-gels (particle size, exclusion limit); super
AW4000 (6 mm, >4 3 105), super AW3000 (4 mm, >6 3
104), and super AW2500 (4 mm, >2 3 103), 15 cm each],
EXPERIMENTAL
Materials
and
a guard column [TSK-guard column Super AW-H,
CO2 (>99.99%) was obtained from Fukuho Teisan. Epichlo-
rohydrin (>99.0%), epibromohydrin (>97.0%), 2-propyn-1-
ol (>98.0%), and 1-aminodecane (>98.0%) were obtained
from Tokyo Kasei Kogyo. 1,6-Diaminohexane (>95.0%), 1,8-
diazabicyclo[5.4.0]-7-undecene (>97.0%), N-ethyldiisopropyl-
amine (>97.0%), sodium azide (>98.0%), sodium hydroxide
(>97.0%), anhydrous N,N-dimethylformamide (>99.5%),
anhydrous tetrahydrofuran (>99.5%), and anhydrous
dimethyl sulfoxide (>99.0%) were obtained from Wako Pure
Chemical Industries. Hydriodic acid (55.0%–58.0%), cop-
per(I) iodide (>99.0%), 1,4-dioxane (>99.5%), sodium
3.5 cm] with DMF containing 0.01M LiBr as an eluent at a
flow rate 0.5 mL/min at 40 8C after calibration with polysty-
rene standards. Thermogravimetric analysis (TGA) was per-
formed from 50 to 500 8C at a heating ratio of 10 8C/min
under nitrogen atmosphere (flow rate: 200 mL/min) on a
Seiko EXSTER6000 system with TGA-6200 instruments. Dif-
ferential scanning calorimetry (DSC) was carried out from
220 to 100 8C at a heating ratio of 5 8C/min under nitrogen
atmosphere (flow rate: 50 mL/min) on a Seiko EXSTER6000
system with DSC-6200 instruments.
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SCHEME 2 Synthesis of bis(cyclic carbonate) monomer containing triazole group.
Synthesis of Catalyst for the Reaction of Epoxides
with CO2
Synthesis of Bis(Cyclic Carbonate) Monomer
Preparation of Glycidyl Propargyl Ether (1)
Synthesis of 1,8-Diazabicyclo[5.4.0]-7-Undecene
Hydroiodide (DBU•HI)
A mixture of epichlorohydrin (18.5 g, 200 mmol) and 2-
propyn-1-ol (5.61 g, 100 mmol) was stirred at 0 8C, and then
sodium hydroxide (4.20 g, 105 mmol) was added to the mix-
ture over a period of 30 min. The resulting mixture was
stirred at 0 8C for 3 h, then the ice bath was removed, and
the reaction temperature was raised to 50 8C. After 12 h at
50 8C, the mixture was diluted with diethyl ether and fil-
tered, and the residue was washed with diethyl ether. The
combined filtrates were washed with water, dried over
sodium sulfate, and the solvents were evaporated in vacuo.
The residue was purified by silica gel column chromatogra-
phy (hexane/chloroform 5 1:1) to give 1 (7.28 g, 65%) as a
A solution of 55% aqueous hydroiodic acid (1 mL, ca. 7.3
mmol) was added dropwise for 1 min to a mixture of 1,8-
diazabicyclo[5.4.0]-7-undecene (609 mg, 4 mmol) in dioxane
(8 mL) at room temperature. After being stirred at room
temperature for 12 h, the mixture was evaporated in vacuo.
The residue was washed with ether, and the precipitate was
dried in vacuo for 4 h at 60 8C to give DBU•HI (1.10 g, 98%)
as a pale yellow powder. Mp 160.6–161.7 8C. 1H NMR
(CDCl3, d, ppm): 1.73–1.86 (m, 6H), 2.12 (quin, 2H, J 5 6.0
Hz), 2.98–3.04 (m, 2H), 3.46–3.52 (m, 2H), 3.60–3.66 (m,
4H), 9.55 (brs, 1H). 13C NMR (CDCl3, d, ppm): 19.2, 23.7,
26.6, 28.8, 32.7, 37.7, 48.9, 54.8, 166.1.
1
colorless liquid. H NMR (CDCl3, d, ppm): 2.47 (t, 1H, J 5 2.4
Hz), 2.64 (dd, 1H, J 5 5.2, 2.8 Hz), 2.81 (t, 1H, J 5 4.6 Hz),
FIGURE 1 1D NMR spectra of a solution of 5 in DMSO-d6 at 25 8C. (a) 1H (400 MHz), (b) 13C (100 MHz), and (c) DEPT-135
(100 MHz).
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FIGURE 4 HMBC NMR spectrum (1H 400 MHz, 13C 100 MHz, 25
8C) of a solution of 5 in DMSO-d6. [Color figure can be viewed
at wileyonlinelibrary.com]
(m, 1H). 13C NMR (CDCl3, d, ppm): 58.8, 66.2, 68.4, 74.6, 75.6,
78.5, 154.7. MS (EI): m/z 5 156 [M]1.
FIGURE 2 Partial H-H COSY NMR spectrum (400 MHz, 25 8C) of
a solution of 5 in DMSO-d6. [Color figure can be viewed at
wileyonlinelibrary.com]
Preparation of (Bromomethyl)Ethylene Carbonate (3)
DBU•HI (280 mg, 1 mmol) was added to epibromohydrin
(2.74 g, 20 mmol) at room temperature. The atmosphere
inside the flask was replaced with CO2 (balloon, ca. 1 atm),
and the reaction mixture was stirred at 45 8C. After 48 h,
the mixture was purified by silica gel column chromatogra-
phy (hexane/acetone 5 3:1) to give 3 (3.59 g, >99%) as a
colorless oil. 1H NMR (CDCl3, d, ppm): 3.55–3.61 (m, 2H),
4.37 (dd, 1H, J 5 9.2, 6.0 Hz), 4.61 (dd, 1H, J 5 8.4, 8.4 Hz),
4.93–4.99 (m, 1H). 13C NMR (CDCl3, d, ppm): 31.2, 68.1,
73.9, 154.1. MS (EI): m/z 5 180, 182 [M]1.
3.16–3.20 (m, 1H), 3.49 (dd, 1H, J 5 11.2, 6.0 Hz), 3.84 (dd,
1H, J 5 11.2, 3.2 Hz), 4.20 (dd, 1H, J 5 16.0, 2.4 Hz), 4.25
(dd, 1H, J 5 16.0, 2.4 Hz). 13C NMR (CDCl3, d, ppm): 44.3,
50.5, 58.4, 70.3, 74.8, 79.2. MS (EI): m/z 5 112 [M]1.
Preparation of (Propargyloxymethyl)Ethylene
Carbonate (2)
DBU•HI (280 mg, 1 mmol) was added to the epoxide 1 (2.24 g,
20 mmol) at room temperature. The atmosphere inside the
flask was replaced with CO2 (balloon, ca. 1 atm), and the reac-
tion mixture was stirred at 45 8C. After 36 h, the mixture was
purified by silica gel column chromatography (hexane/
Preparation of (Azidomethyl)Ethylene Carbonate (4)
Sodium azide (1.30 g, 20 mmol) was added to a solution of
3 (3.62 g, 20 mmol) in anhydrous N,N-dimethylformamide
(20 mL) at room temperature. After being stirred at 25 8C
for 12 h, the mixture was concentrated to one fourth of its
original volume in vacuo at 30 8C. The residue was diluted
with ethyl acetate and washed with water, and the aqueous
1
acetone 5 3:1) to give 2 (3.10 g, >99%) as a colorless oil. H
NMR (CDCl3, d, ppm): 2.50 (t, 1H, J 5 2.4 Hz), 3.75 (dd, 1H,
J 5 10.6, 4.0 Hz), 3.80 (dd, 1H, J 5 10.4, 4.0 Hz), 4.21 (dd, 1H,
J 5 16.0, 2.0 Hz), 4.28 (dd, 1H, J 5 16.2, 2.4 Hz), 4.41 (dd, 1H,
J 5 8.0, 6.0 Hz), 4.52 (dd, 1H, J 5 8.4, 8.4 Hz), 4.82–4.88
FIGURE 3 Partial HMQC NMR spectrum (1H 400 MHz, 13C 100
MHz, 25 8C) of a solution of 5 in DMSO-d6. [Color figure can be
viewed at wileyonlinelibrary.com]
FIGURE 5 Time conversion curves of two cyclic carbonates
of 5. Reaction conditions: 0.5 mmol of 5,
1 mmol of
CH3(CH2)9NH2, 0.5 mL of anhydrous DMSO, and 80 8C for 24 h.
4
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SCHEME 3 Synthesis of poly(hydroxyurethane)s containing triazole segment (secondary and primary hydroxyl groups exist ran-
domly, but simplified as illustrated).
phase was extracted with ethyl acetate. The combined
organic layers were dried over sodium sulfate, and the sol-
vents were evaporated in vacuo. The residue was purified by
silica gel column chromatography (chloroform) to give 4
(2.67 g, 93%) as a colorless oil. 1H NMR (CDCl3, d, ppm):
3.57 (dd, 1H, J 5 13.4, 4.0 Hz), 3.72 (dd, 1H, J 5 13.4, 4.0
Hz), 4.32 (dd, 1H, J 5 8.8, 6.4 Hz), 4.53 (dd, 1H, J 5 8.4, 8.4
Hz), 4.81-4.87 (m, 1H). 13C NMR (CDCl3, d, ppm): 52.0, 66.3,
74.0, 154.0. MS (EI): m/z 5 143 [M]1.
dimethyl sulfoxide (1 mL) was added to the mixture of 5
(598 mg, 2 mmol) in anhydrous dimethyl sulfoxide (1 mL)
at room temperature, and was stirred at 100 8C. After
24 h, the mixture was cooled to rt, and was precipitated
into acetone. The precipitate was washed with acetone and
dried at 40 8C in vacuo to give 6a (765 mg, 92%) or 6b
(835 mg, 93%) as a pale orange sticky solid. The obtained
poly(hudroxyurethane)s were analyzed by 1H NMR, SEC,
TGA, and DSC.
Synthesis of 4-[(1,3-Dioxolane-2-One-4-Ylmethoxy)Methyl]-
1-(1,3-Dioxolane-2-One-4-Ylmethyl)-1H-[1,2,3]Triazole (5)
Copper(I) iodide (95 mg, 0.5 mmol) was added to a mixture
of 2 (781 mg, 5 mmol), 4 (716 mg, 5 mmol) and N-ethyldii-
sopropylamine (711 mg, 5.5 mmol) in anhydrous tetrahydro-
furan (50 mL) at room temperature. The resulting mixture
was stirred at 25 8C for 12 h, and then the mixture was
evaporated in vacuo. The residue was purified by silica gel
column chromatography (chloroform/acetonitrile 5 2:1) to
give 5 (1.29 g, 86%) as a white solid. Mp 83.5–85.2 8C. 1H
NMR (DMSO-d6, d, ppm): 3.62 (ddd, 1H, J 5 12.8, 4.2,
1.0 Hz), 3.72 (dd, 1H, J 5 11.2, 2.4 Hz), 4.19–4.24 (m, 1H),
4.33 (ddd, 1H, J 5 9.0, 6.0, 1.0 Hz), 4.51 (dd, 1H, J 5 8.6, 8.6
Hz), 4.58–4.66 (m, 3H), 4.82 (d, 2H, J 5 5.2 Hz), 4.90–4.96
(m, 1H), 5.18–5.25 (m, 1H), 8.14 (s, 1H). 13C NMR (DMSO-d6,
d, ppm): 50.9, 63.7, 66.0, 66.6, 68.9, 74.7, 75.3, 125.1, 143.6,
154.2, 154.9. MS (EI): m/z 5 299 [M]1.
RESULTS AND DISCUSSION
Synthesis of Triazole-Linked Bifunctional Five-Membered
Cyclic Carbonate (5)
Scheme 2 shows the three-step convergent synthesis of 5 via
click reaction. First, the glycidyl propargyl ether (1) was syn-
thesized by ring-opening addition of propargyl alcohol to
epichlorohydrin and subsequent ring-closing reaction in the
presence of sodium hydroxide in moderate yield. Next, the
ring-expansion addition of 1 and epibromohydrin with CO2
were carried out in bulk using a catalytic amount of amidi-
nium salt at ordinary pressure and 45 8C. Investigation of
the catalytic effects of amidinium salts has been already
reported in the literature.30 The use of DBU•HI gave the cor-
responding five-membered cyclic carbonates 2 and 3 in high
yields. The azide-substituted cyclic carbonate (4) was
obtained by treatment of 3 with an equimolar amount of
sodium azide in 93% yield. Finally, the copper (I)-catalyzed
cycloaddition between the azide (4) and the alkyne (2) pro-
ceeded at ambient temperature to afford the desired bis
(cyclic carbonate) monomer (5) in 86% yield. The character-
ization of 5 was achieved by 1D (1H, 13C and DEPT-135) and
2D (H-H COSY, HMQC, and HMBC) NMR spectra. As shown in
Figure 1, the 1H NMR spectrum showed a singlet at low
Synthesis of Poly(Hydroxyurethane)s
General Procedure for the Synthesis of
Poly(Hydroxyurethane)s Containing Triazole Segment
(6a,b)
A solution of 1,6-diaminohexane (232 mg, 2 mmol) or 1,2-
bis(2-aminoethoxy)ethane (296 mg, 2 mmol) in anhydrous
TABLE 1 Results of Polyaddition Reaction of 5 with Diamine
Conv.
(%)a
Yield
(%)b
Mn
Mw
Mw/Mn
(-)c
Tg
(8C)d
Td5
(8C)e
Td10
(8C)e
Polymer
(g mol21 c
)
(g mol21 c
)
6a
6b
>99
>99
92
93
14,500
7,400
54,700
15,900
3.77
2.15
35
19
244
241
263
266
a
d
Determined by 1H NMR.
Measured by DSC.
b
c
e
Isolated yield after precipitation with acetone.
Estimated by SEC (DMF containing 10 mM LiBr, polystyrene
Measured by TGA.
standard).
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FIGURE 6 1H NMR spectra of a solution of 6a or 6b in DMSO-d6 at 25 8C. Asterisks denote the remaining acetone used for
purification.
magnetic field of 8.1 ppm assignable to the methine proton
of the triazole ring. The signal of the methine carbon of the
triazole ring was observed at ca. 125 ppm in the 13C and
DEPT-135 NMR spectra. The signal of the quaternary carbon
of the triazole ring was observed at 143.6 ppm in the 13C
NMR spectrum, and two peaks assignable to the carbonyl
groups of the two cyclic carbonate rings were shown at low
magnetic field of 154.2 and 154.9 ppm. As shown in Figure
2, the proton signals of two different cyclic carbonate moie-
ties were identified by H-HCOSY spectrum. The signal of the
methylene proton at the 4-position of triazole ring and the
carbon signals of two different cyclic carbonate moieties
were assigned by HMQC and HMBC spectra (Figs. 3 and 4).
All the signals could be reasonably assigned in accordance
with the crosspeaks.
Synthesis and Characterizations of
Poly(Hydroxyurethane)s (6a,b)
First, we investigated the reactivity of two different cyclic
carbonate groups of 5 by aminolysis using monofunctional
amine. As shown in Figure 5, the reaction of 5 was carried
out with two equivalents of 1-aminodecane at 80 8C without
catalyst. The conversion of two cyclic carbonate groups of 5
was calculated by the integration of 1H NMR signals. The
TABLE 2 The Solubility of Poly(Hydroxyurethane)s
H2O
MeOH
EtOH
CH3CN
DMAc
DMF
NMP
DMSO
6a
6b
–
–
–
–
11
11
11
CHCl3
–
11
11
THF
–
11
11
1
–
–
11
11
Hexane
Toluene
Et2O
EtOAc
CH2Cl2
Acetone
6a
6b
–
–
–
–
–
–
–
–
–
–
–
–
–
–
11: soluble, 1: partially soluble, –: insoluble. Conditions: 2 mg/mL, 150 rpm at 25 8C for 1 h.
6
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rings were observed at ca. 8.0 ppm as in the case of the 1H
NMR spectrum of 5. The assignment of the signals for the
active hydrogen atoms such as amide groups (7.0–7.2 and
6.7–6.9 ppm), secondary hydroxyl groups (5.4 and 5.0 ppm),
and primary hydroxyl groups (5.1 and 4.8 ppm) were con-
firmed by the disappearance of the signals by the addition of
D2O. The ratios of the secondary and the primary hydroxyl
groups of 6a and 6b were estimated to 74:26 and 73:27,
respectively, by the integration ratio of the triazole proton
signal to the a-methine proton signals of the primary
hydroxyl groups (Supporting Information, Fig. S1). The solu-
bility of poly(hydroxyurethane)s (6a-b) are listed in Table 2.
The polymer 6a was soluble in highly polar aprotic solvents,
such as N,N-dimethylacetamide (DMAc), N,N-dimethylforma-
mide (DMF), 1-methyl-2- pyrrolidone (NMP), and dimethyl
sulfoxide (DMSO), but insoluble in nonpolar, low-polarity,
and protic solvents. Poly(hydroxyurethane) containing ethyl-
ene glycol segment (6b) showed good solubility in water,
whereas poly(hydroxyurethane) obtained from 1,6-diamino-
hexane (6a) was insoluble. This result clearly demonstrated
that both the hydrophobic and the hydrophilic poly(hydrox-
yurethane)s containing triazole segment can be synthesized
by using the choice of either alkyl moiety- or ether moiety-
containing diamine. The thermal stabilities of 6a and 6b
were studied by TGA. Figure 7 shows the TGA curves
obtained at a heating rate of 10 8C/min under a nitrogen
flow. The 5% and 10% weight loss temperatures (Td5 and
Td10) of 6a and 6b were shown in Table 1. The thermal deg-
radation behaviors were almost identical, and the Td5 and
Td10 were determined to be around 242 8C and 265 8C,
respectively. The thermal phase transitions of 6a and 6b
were examined by DSC. Figure 8 shows the DSC curves
obtained at the second heating scan at a rate of 5 8C/min
under a nitrogen flow. The value of glass transition tempera-
ture (Tg) of 6b was observed at 19 8C, which is lower than
that of 6a observed at 35 8C. It seems that the Tg values
were affected by molecular weights of 6a and 6b. The poly
(hydroxyurethane)s (6a,b) can be applied to biopolymeric
materials and electrolytes, because 6a and 6b have good Tg
values around room temperature.
FIGURE 7 TGA curves of 6a (solid line) and 6b (dashed line)
from 50 to 500 8C (10 8C/min) under N2 atmosphere (200 mL/
min).
cyclic carbonate at the side of triazole ring (N-CC) was more
reactive than the other cyclic carbonate at the side of ether
group (O-CC). The conversion of N-CC was more than 99%
within 6 h, whereas the conversion of O-CC was not com-
pleted even after 24 h. Thus the reaction temperature needs
more than 80 8C to complete the reaction within 24 h. The
novel bis(cyclic carbonate) (5) could be applied to the syn-
thesis of poly(hydroxyurethane)s by the polyaddition reac-
tion with diamines. As shown in Scheme 3, the reaction of 5
was carried out with stoichiometric amount of 1,6-diamino-
hexane or 1,2-bis(2-aminoethoxy)ethane at 100 8C without
catalyst. The results of the polyaddition reactions are sum-
marized in Table 1. The conversion of 5 was calculated by
the integration of 1H NMR signals. The polymeric products
(6a-b) were isolated as pale orange sticky solids simply by
precipitation with acetone in high yield. The number average
molecular weight of 6a (Mn 14,500) estimated by SEC was
1.96 times higher than that of 6b (Mn 7,400); however, the
polydispersity index of 6a (Mw/Mn 3.77) had a much
broader distribution than that of 6b (Mw/Mn 2.15). The 1H
NMR spectra of poly(hydroxyurethane)s are shown in
Figure 6. The signals of the methine protons of the triazole
CONCLUSIONS
The azide- and the alkyne-substituted five-membered cyclic
carbonates were synthesized by two steps via ring-expansion
addition of epoxides with CO2, and the addition reaction pro-
ceeded under ordinary pressure in the presence of catalytic
amount of DBU•HI in high yield. The click reaction of obtained
cyclic carbonates was carried out to give the novel triazole-
linked bifunctional five-membered cyclic carbonate in high
yield. Both the hydrophobic and the hydrophilic poly(hydrox-
yurethane)s containing triazole segment were obtained in high
yield by polyaddition of novel bis(cyclic carbonate) and dia-
mines without catalyst. The thermal degradation behaviors of
poly(hydroxyurethane)s were almost identical, and the Td5
were determined to be around 242 8C. It is envisioned that
ionic conductive poly(hydroxyurethane)s can be designed and
FIGURE 8 DSC curves of the second heating run of 6a (solid
line) and 6b (dashed line) from 220 to 100 8C (5 8C/min) under
N2 atmosphere (50 mL/min).
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7

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