Electronic Supplementarymaterials

Electronic SupplementaryMaterials

Preparation of Stimuli-Responsive Hydrogel Networks withThreadedβ-Cyclodextrin End-Capped Chains via Combination ofControlled RadicalPolymerization and Click Chemistry

Tao Cai,aWen 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: (XL Zhu); (ET Kang)

Figure S1.XPS widescan, C 1sand 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%) andpropargyl alcohol (PA, 99%)were obtained from Sigma-Aldrich Chem. Co. and used as received without further purification. Dichloromethane (DCM, reagent grade)was obtained from MerckChem. Co. andused as received without further purification. S,S'-bis(α,α'-dimethyl-α''-acetic acid)trithiocarbonate (BDAT)1,2was 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 literaturewith 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 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 CH2Cl2and 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).

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).

Figure S3.1H NMR spectra of (a) PEG-b-PPG-b-PEG and (b) PEG-b-PPG-b-PEG diacrylate block copolymers.

Figure S4.Typical DSC thermograms of the (a)primary PEG-b-PPG-b-PEG, (b) sliding-ring PEG-b-PPG-b-PEG-thread-βCD, (c)sliding-ring PEG-b-PPG-b-PEG-thread-βCD-capped-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-PMES68hydrogels, and (a′)PEG-b-PPG-b-PEG and βCD-capped-PMES53(1:1, w/w) blend hydrogels.

References

[1] J. T.Lai, D.Filla, R.Shea,Macromolecules,2002, 35, 6754-6756.

[2] S. H. Thang, Y. K. Chong, R. T. A. Mayadunne, G. Moad, E. Rizzardo, Tetrahedron, 1990, 40, 2435-2438.

[3] T.Zhang, Z. H.Zheng, X. B.Ding, Y. X. Peng, Macromol. Rapid Commun.,2008, 29, 1716-1720.

[4] L.Wang, K.Zeng, S. X.Zheng,ACS Appl. Mater. Interface,2011, 3, 898-909.

[5] X. M.Lian, J.Jin, J.Tian, H. Y.Zhao, ACS Appl. Mater. Interface,2010, 2, 2261-2268.

[6] F.Cellesi, N.Tirelli, J. A.Hubbell,Macromol. Chem. Phys.,2002, 203, 1466-1472.

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