Supporting Information
Metal- and Solvent-Free, Clickable Synthesis and
Postpolymerization Functionalization of Poly(triazole)s
FENGYANG DENG 1, BIN XU 1, YONG GAO 1*, ZHENG LIU 1, DUANGUANG YANG 1, HUAMING LI 1, 2*
1
College of Chemistry, Xiangtan University, Xiangtan 411105, Hunan Province, P. R. China
2
Key Laboratory of Polymeric Materials & Application Technology of Hunan Province, Key
Laboratory of Advanced Functional Polymeric Materials of College of Hunan Province, and Key
Lab of Environment-Friendly Chemistry and Application in Ministry of Education, Xiangtan
411105, Hunan Province, P. R. China
*Corresponding author. Tel.: +86 731 58298572; Fax: +86 731 58293264.
E-mail address: lihuaming@xtu.edu.cn (H. M. Li).
1
1. General
Methyl 3,5-dihydroxybenzonate was recrystallized from the mixed solvent of methanol and water
(1/9, v/v). Propargyl bromide was dried over anhydrous MgSO4, distilled under reduced pressure.
1,4-Dibromobutane was dried over anhydrous MgSO4, distilled under reduced pressure. All other
chemicals and solvents were of reagent grade quality and used without further purification unless
otherwise noted. NMR spectra were recorded with a 400 MHz Bruker AV-400 NMR spectrometer.
FTIR spectra in KBr pellets were recorded on a PE Spectrum One FTIR spectrometer. The
elemental analyses were performed using an Elementar Vario EL-III instrument. Typically, each
sample was measured four times, and the average value was given to present the elemental content.
Mass spectra (MS) were recorded on a Bruker Autoflex TOF/TOF (MALDI-TOF) instrument.
Spectra were acquired in the linear mode. The molecular weight and polydispersity index of polymer
were determined by a PL-GPC120 setup equipped with a PL HTRI RI detector, and a column set
consisting of two PL gel 5μm mixed-D columns (7.5 × 300 mm, effective molecular weight range
of 0.2-400.0 kg/mol) using DMF that contained 1.0 g/L LiBr as an eluent at 80 ºC at a flow rate of
1.0 mL/min. The molecular weights of the polymers were calculated relative to linear polystyrene
standards. Thermogravimetric analysis (TGA) measurement was performed on a Netzsch TG 209
analyzer under nitrogen at a scan rate of 5 ºC/min. Thermal analysis was performed with a
differential scanning calorimetry (DSC) TA Q10 instrument under nitrogen atmosphere at a scan
rate of 10 ºC/min. The recorded temperatures were calibrated using Indium as standard.
2
2. Synthesis of Monomers
2.1. Synthesis of Methyl 3,5-dipropargyloxylbenzoate
Propargyl bromide (9.33 g, 78.4 mmol), methyl 3,5-dihydroxybenzoate (3.07 g, 18.3 mmol),
K2CO3 (7.53 g, 54.6 mmol), and dried acetone (100 mL) were added into a 250 mL flask. The
mixture was stirred for 48 h at room temperature. The resulting mixture was diluted with 300 mL
of water. After extraction with dichloromethane (4 × 80 mL), the combined organic phase was
washed with brine (4 × 80 mL) and dried with anhydrous MgSO4. The solvent was removed by
rotary evaporator and the crude product was subsequently purified by silica gel chromatography
using petroleum ether/EtOAc as (6/1, v/v) the eluent, to yield a white solid (4.04 g, 90.5%). 1H
NMR (CDCl3, δ, ppm): 7.30 (d, 2H, J = 2.13 Hz, Ar-H), 6.81 (s, 1H, Ar-H), 4.72 (d, 4H, J = 2.02
Hz, CH2), 3.91 (s, 3H, CH3), 2.54 (s, 2H, C≡CH). IR (KBr), ν (cm-1): 3293, 3270, 3092, 2960,
2924, 2854, 2132, 1715, 1601, 1457, 1434, 1266, 1245.
2.2. Synthesis of Methyl 3,5-bis(4-azidobutoxy)benzoate
3
The synthesis of methyl 3,5-bis(4-azidobutoxy)benzoate was performed by two successive
processes. Firstly, methyl 3,5-dihydroxybenzoate (4.69 g, 27.9 mmol) in dry acetone (200 mL) was
added dropwise to a mixture of 1,4-dibromobutane (16.6 g, 76.9 mmol) and K2CO3 (22.1 g, 160
mmol) in dry acetone (100 mL) at room temperature. After complete addition, the reaction mixture
was allowed to stir for 72 h at room temperature. The resulting mixture was diluted with 300 mL
of water. After extraction with dichloromethane (4 × 60 mL), the combined organic phase was
washed with brine (4 × 60 mL) and dried with anhydrous MgSO4 overnight and filtered. The
filtrate was concentrated and purified by a silica gel column using petroleum ether/EtOAc (10/1,
v/v) as eluent. A yellow transparent viscous liquid of methyl 3,5-bis(4-bromobutoxy)benzoate was
obtained (7.11 g, 70.3%). 1H NMR (CDCl3, δ, ppm): 7.16 (d, 2H, J = 1.96 Hz, Ar-H), 6.63 (t, 1H,
J1 = 2.45 Hz, J2 = 2.43 Hz Ar-H), 4.01 (t, 4H, J1 = 6.36 Hz, J2 = 5.87 Hz, OCH2), 3.90 (s, 3H, CH3),
3.49 (t, 4H, J1 = 6.87 Hz, J2 = 6.34 Hz, CH2Br), 2.07 (m, 4H, CH2), 1.95 (m, 4H, CH2).
Secondly, a mixture of the as-produced methyl 3,5-bis(4-bromobutoxy)benzoate (5.87 g, 13.4
mmol) and NaN3 (3.05 g, 46.9 mmol) in 100 mL of DMF/H2O mixture (7/1, v/v) was stirred at
room temperature for 48 h. The resulting mixture was diluted with 300 mL of water. After
extraction with dichloromethane (4 × 60 mL), the combined organic phase was washed with brine
(4 × 60 mL) and dried with anhydrous MgSO4. After filtration, the filtrate was concentrated and
purified by a silica gel column using petroleum ether as the eluent. A light yellow transparent
viscous liquid was obtained (4.34 g, 89.3%). 1H NMR (CDCl3, δ, ppm): 7.16 (d, 2H, J = 1.81 Hz,
Ar-H), 6.63 (s, 1H, Ar-H), 4.01 (t, 4H, J1 = 6.11 Hz, J2 = 6.10 Hz, OCH2), 3.90 (s, 3H, CH3), 3.37
(t, 4H, J1 = 6.72 Hz, J2 = 6.40 Hz, CH2N3), 1.88 (m, 4H, CH2), 1.79 (m, 4H, CH2).
13
C NMR
(CDCl3, δ, ppm): 166.50, 159.86, 131.95, 107.68, 106.36, 67.44, 51.97, 51.03, 26.32, 25.59. IR
4
(KBr), ν (cm-1): 2952, 2876, 2099, 1722, 1596, 1445, 1176, 1245. Anal. Calcd for C16H22N6O4: C,
53.03; H, 6.12; N, 23.19. Found: C, 53.05; H, 6.10; N, 23.16. Calcd: [M]+ m/z = 362.384. Found
TOF-MS: [M + K]+ = 401.305.
3. Postpolymerization Functionalization
3.1. Synthesis of PTAII-1
PTAII (1.30 g, 4.29 mmol based on benzoate moiety) was dissolved in DMF (20 mL) and
hydrazine hydrate (25 mL, 0.40 mol) was added dropwise over a period of 0.5 h. The resulting
solution was allowed to stir at 75 ºC for 24 h. After completion of reaction, the mixture was poured
into 100 mL of water to precipitate polymer. The functionalized polymer (PTAII-1) was collected
by filtration, washed several times with distilled water and dried under vacuum at room
temperature. 1H NMR (DMSO-d6, δ, ppm): 9.72, 8.26, 7.83, 7.12-6.48, 5.32, 5.15, 4.45, 3.99, 1.97,
1.68. IR (KBr), ν (cm-1): 3419, 3326, 2935, 28775, 166059, 1590, 11664, 1053.
3.2. Synthesis of PTAII-2
PTAII-1 (1.30 g, 4.29 mmol based on benzohydrazide moiety) was dissolved in DMF (20 mL). To
this a solution of KOH (0.36 g, 6.46 mmol) in absolute ethanol (9.0 mL) was added followed by
drop wise addition of carbon disulphide (0.49 g, 6.45 mmol) at 0 ºC. The reaction mixture was
stirred at this temperature for 15 h. After completion of reaction, the potassium salt of the polymer
5
obtained was poured into absolute ethanol (50 mL). The separated product was filtered, washed
with absolute ethanol to yield PTAII-2. The potassium salt thus obtained was in quantitative yield
and was used in the next step without further purification.
3.3. Synthesis of PTAII-3
A solution of the as-synthesized PTAII-2 in water (10 mL) and hydrazine hydrate (30 mL) was
stirred at 75 ºC for 3 h. The color of the reaction mixture changed to green with the evolution of
hydrogen sulfide gas. The reaction mixture was then cooled to room temperature and diluted with
water (20 mL). Upon acidification with hydrochloric acid, the polymer was precipitated out of the
solution. The functionalized polymer (PTAII-3) was collected by filtration, washed several times
with distilled water. 1H NMR (DMSO-d6, δ, ppm): 13.96, 8.27, 7.83, 7.35-6.62, 5.78, 5.36, 5.18,
4.45, 4.02, 3.34, 1.98, 1.70. IR (KBr), ν (cm-1): 3412, 2929, 2622, 1650, 1596, 1559, 1514, 1441,
1405, 1258, 1224, 1053, 948, 847.
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SCHEME S1
Flow Chart of the Multi-Step Fractionation Experiment
(i) Dissolved in CH2Cl2 and precipitated in acetone;
(ii) Evaporated to dryness, dissolved in CH2Cl2 and precipitated in acetone/ethyl acetate (1/1, v/v);
(iii) Evaporated to dryness, dissolved in CH2Cl2 and precipitated in ethyl acetate.
7
*
b
HO
OH
d
a
COOCH3 d
a
b
B
~
O
c
d
c
e
b
O
a
COOCH3 d
*
a
8
e
b
7
A
6
5
4
3
2
Chemical shift (ppm)
1
0
FIGURE S1 1H NMR spectra of (A) methyl 3,5-dipropargyloxylbenzoate in CDCl3, and (B)
methyl 3,5-dihydroxybenzoate in D2O. The solvent peaks are marked with asterisks.
8
~
g
O
k
O
i
Br
j
h
f
COOCH3 d
d
*
h
f
b
jk
g
g
~
O
k
O
h
B
i
N3
j
f
d
h
COOCH3 d
*f
8
7
g
b
jk
6
5
4
3
2
Chemical shift (ppm)
A
1
0
FIGURE S2 1H NMR spectra of methyl 3,5-bis(4-azidobutoxy)benzoate (A), and methyl
3,5-bis(4-bromobutoxy)benzoate (B) in CDCl3. The solvent peaks are marked with asterisks.
9
FIGURE S3 13C NMR spectrum of methyl 3,5-bis(4-azidobutoxy)benzoate in CDCl3. The solvent
peak is marked with asterisk.
10
C
B
A
8
7
6
5
4
3
2
1
0
Chemical shift (ppm)
FIGURE S4 1H NMR spectra of the as-prepared methyl 3,5-dipropargyloxylbenzoate (A), and
after 36 h of heat treatment at 80 oC (B), and 100 oC (C), respectively.
11
C O
H
C
B
A
10
8
6
4
2
0
Chemical shift (ppm)
FIGURE S5 1H NMR spectra of the as-prepared methyl 3,5-bis(4-azidobutoxy)benzoate (A), and
after 36 h of heat treatment at 80 oC (B), and 100 oC (C), respectively.
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SCHEME S2
Proposed Thermal Side Reactions for Diazide Monomer
It is worthy of note that the signals at δ 2.96, and 2.88 ppm in Fig. S5 might be assigned to the
methylene protons neighboring to the nitrogen atom in the pyrilidine ring.
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36 h
28 h
20 h
12 h
8h
4h
2h
0h
2200
2000
1800
1600
1400
1200
-1
Wavenumber (cm )
FIGURE S6 FTIR spectra of polymerization mixture at different reaction time.
14
C
B
A
3750
3000
2250
1500
750
-1
Wavenumber (cm )
FIGURE S7 FTIR spectra of the diazide (A), dialkyne (B), and PTAII (C).
15
Endo
PTAII
PTAII-3
30
60
90
120
150
o
Temperature ( C)
FIGURE S8 DSC curves of PTAII and PTAII-3 at a scan rate of 10 oC/min in nitrogen.
16
180
PTAII
PTAII-3
-0.8
80
-0.6
60
TP2
TP
-0.4
40
TP1
-0.2
20
0
0.0
150
300
450
600
150
300
450
600
o
Temperature ( C)
FIGURE S9 TGA curves of PTAII and PTAII-3 at a heating rate of 5 oC/min in nitrogen.
17
dW/dT
Mass Loss (%)
100
PTAII-3
PTAII
10
12
14
Elution time (min)
FIGURE S10 GPC traces of PTAII and PTAII-3 in DMF.
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16