Electronic Supplementary Materials
Preparation of Stimuli-Responsive Hydrogel Networks with Threaded βCyclodextrin End-Capped Chains via Combination of Controlled Radical
Polymerization and Click Chemistry
Tao Cai,a Wen Jing Yang,a Zhengbiao Zhangb, Xiulin Zhu*,b, Koon-Gee Neoha,c
and En-Tang Kang*,a,c
aNUS
Graduate School for Integrative Science and Engineering
National University of Singapore
Kent Ridge, Singapore 117576
bSchool
of Chemistry & Chemical Engineering
Soochow University
Suzhou, PR China 215006
cDepartment
of Chemical & Biomolecular Engineering
National University of Singapore
Kent Ridge, Singapore 119260
*To whom correspondence should be addressed
Email address: xlzhu@suda.edu.cn (XL Zhu); cheket@nus.edu.sg (ET Kang)
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Figure S1. XPS wide scan, C 1s and N 1s core-level spectra of the azido-βCD powder.
Other materials
Acryloyl chloride (97%), 4-(N,N-dimethylamino)pyridine (DMAP, ≥99%), poly(ethylene
glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (Pluronic® F-108,
PEG-b-PPG-b-PEG, 82.5 wt% of PEG, Mn=14,600 g/mol), triethylamine (TEA, ≥99%),
N-ethyl-N'-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDAC, ≥99%) and
propargyl alcohol (PA, 99%) were obtained from Sigma-Aldrich Chem. Co. and used as
received without further purification. Dichloromethane (DCM, reagent grade) was
obtained from Merck Chem. Co. and used as received without further purification. S,S'bis(α,α'-dimethyl-α''-acetic acid)trithiocarbonate (BDAT)1,2 was prepared according to
procedures described in the literature.
Synthesis of S,S'-bis(α,α'-dimethyl-α''-propargyl acetate)trithiocarbonate (BDPT)
S,S'-bis(α,α'-dimethyl-α''-propargyl
acetate)trithiocarbonate
(BDPT)
was
prepared
according to the method reported in literature with slight modification.3-5 BDAT (0.50 g,
1.77 mmol), EDAC (1.02 g, 5.3 mmol), DMAP (0.65 g, 5.3 mmol) and anhydrous
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CH2Cl2 (10 ml) were introduced into a 25 ml single-necked round bottom flask. The flask
was immersed in an ice bath, and propargyl alcohol (0.5 ml, 8.6 mmol) in 5 ml of dry
CH2Cl2 was added drop-wise. Upon completion of the addition, the solution was stirred at
room temperature for 24 h. The product was washed with doubly distilled water and brine
several times. The combined organic layer was dried over magnesium sulfate and
concentrated by rotary evaporator. About 0.45 g of a yellow liquid was obtained (yield
~71%). 1H NMR (CDCl3, δ, ppm, TMS): 1.67 (12H, -CH3), 2.46 (2H, -C≡CH), 4.68 (4H,
-COOCH2-).
Synthesis of PEG-b-PPG-b-PEG Diacrylate6
In a typical reaction, PEG-b-PPG-b-PEG (7.3 g, 0.5 mmol), TEA (0.25 g, 2.5 mmol) and
CH2Cl2 (20 ml) were introduced into a 50 ml single-neck round-bottom flask. The
reaction flask was immersed in an ice bath at 0 ºC. Acryloyl chloride (0.23 g, 2.5 mmol)
in 5 ml anhydrous CH2Cl2 was added dropwise to the flask. After the addition, the flask
was sealed, and the mixture was left to react at room temperature for 24 h. At the end of
the reaction, the mixture was filtered to remove the precipitated salt and the filtrate was
precipitated in an excess amount of anhydrous diethyl ether. The precipitated copolymers
were purified by re-dissolving in CH2Cl2 and re-precipitation in diethyl ether. The
dissolution-re-precipitation cycle was repeated twice. The purified product was dried
under reduced pressure at room temperature. About 7.0 g of a white solid was obtained
(yield ~95%). 1H NMR (CDCl3, δ, ppm, TMS): 1.12 (methyl group of PPG), 3.4
(methylidyne group of PPG), 3.55 (methylene group of PPG), 3.65 (methylene group of
PEG), 4.3 (4H, -COOCH2-), 5.8 (2H, CH2=CH), 6.15 and 6.4 (4H, CH2=CH).
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a
S
c
O
O
S
S
O
O
b
a
b
c
(b)
a
S
HO
OH
S
a
S
O
O
4
3
(a)
6
5
2
1
0
Chemical shift (ppm)
Figure S2. 1H NMR spectra of (a) S,S'-bis(α,α'-dimethyl-α''-acetic acid)trithiocarbonate
(BDAT) and (b) S,S'-bis(α,α'-dimethyl-α''-propargyl acetate)trithiocarbonate (BDPT).
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d
O
O
a
b O
O m
c n
O p
f
O
g
e
a
d
O
c
b
g
f
(b)
HO
O
e
d
a
b
d
O m
O
c
n
O p
OH
a
c
b
(a)
7
6
5
4
3
2
1
0
Chemical shift (ppm)
Figure S3. 1H NMR spectra of (a) PEG-b-PPG-b-PEG and (b) PEG-b-PPG-b-PEG
diacrylate block copolymers.
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(e)
(d)
(c)
Exo.
(b)
39.8 ºC
42.6 ºC
45.1 ºC
55.4 ºC
(aʹ)
Endo.
56.1 ºC
(a)
58.6 ºC
20
40
60
Temperature (℃)
80
Figure S4. Typical DSC thermograms of the (a) primary PEG-b-PPG-b-PEG, (b) slidingring PEG-b-PPG-b-PEG-thread-βCD, (c) sliding-ring PEG-b-PPG-b-PEG-thread-βCDcapped-PMES36, (d) sliding-ring PEG-b-PPG-b-PEG-thread-βCD-capped-PMES53 and (e)
sliding-ring PEG-b-PPG-b-PEG-thread-βCD-capped-PMES68 hydrogels, and (a′) PEG-bPPG-b-PEG and βCD-capped-PMES53 (1:1, w/w) blend hydrogels.
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