Supporting information. ph- and Thermal-Responsive Multishape Memory Hydrogel

Transcription

1 Supporting information ph- and Thermal-Responsive Multishape Memory Hydrogel Xiao-Lei Gong,,, # Yao-Yu Xiao,, # Min Pan, Yang Kang, Bang-Jing Li,* and Sheng Zhang* State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute of Sichuan University, Chengdu , China. Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu , China. Library of Shenzhen People s Hospital, 2 nd Clinical Medical College of Jinan University, Shenzhen , China. * Correspondence and requests for materials should be addressed to Sheng Zhang ( zslbj@163.com) or Bang-Jing Li ( libj@cib.ac.cn). # These authors contributed equally to this work. 1 Materials All chemicals were commercially available and were used as received without further purification. Dansyl chloride, N,N'-methylenebisacrylamide (MBA), methacrylic anhydride and methacrylic anhydride were purchased from J&K Scientific Ltd. Acrylamide (AAm) was purchased from Aladdin Reagent Database Inc. Ethylenediamine, methanol, dichloromethane (DCM), dimethyl sulfoxide (DMSO), ethyl acetate, hexane,acetone,2-propanol, hydrochloric acid and NaOH were purchased from ChengDu Kelong Chemical Co.,Ltd., and all the other chemicals and solvents were also analytical grade and local commercial products. 1H NMR spectra were recorded on an Advance Bruker 600 NMR spectrometer at 600 MHz at room temperature. A PHS-3C digital ph meter was utilized to measure the ph values of aqueous solutions. 2 Preparation of N-[(5-N,N-Dimethylaminonaphthylsulfonylamino)ethyl]-2-methacrylamide (DnsEMA). - S-1 -

2 Scheme S1 The preparation route of DnsEMA. 2.1 Preparation of 2-Aminoethyl methacrylamide hydrochloride (AEMA) Ethylenediamine (11 ml, 0.16 mol) was added to an ethylenediamine dihydrochloride solution(10 g, 75 mmol, in 200 ml distilled water) in a three-necked round-bottom flask fitted with a head stirrer and a thermometer. After 1 h of stirring, methanol (230 ml) was added and the mixture was cooled down to -30 C. Methacrylic anhydride (22 ml, 0.15 mol) and 4-Methylphenol were first mixed with methanol (30 ml) and subsequently added to the mixture. After the coplete addition of the methacrylic anhydride, the solution was maintained at -30 C for 75 min and then hydrochloric acid (24 ml) was added. The ph of the solution was recorded and the solution was maintained at a ph of ~1 overnight. Finally, the solvent was removed under vacuum; the crude creamy product was washed with acetone. The product was extracted by hot 2-propanol and followed by crystallization in cold 2-propanol. 2-Aminoethyl methacrylamide hydrochloride (AEMA) was obtained. AEMA: 1 H NMR (600 MHz, D 2 O, ppm): δ5.67 (s,1h, olefin), δ 5.40 (s,1h, olefin), δ 3.47 (t, 2H, -NH-CH 2 -),δ3.08 (t, 2H, -CH 2 -NH 2 ), δ 1.83 (s, 3H, -CH 3 ). - S-2 -

3 Figure S1 1 H NMR Spectrum of AEMA. 2.2 Preparation of N-[(5-N,N-Dimethylaminonaphthylsulfonylamino)ethyl]-2-methacrylamide (DnsEMA). AEMA (1.282 g, 0.01 mol) was suspended in 100 ml of dichloromethane (DCM).Then triethylamine(2.08ml, 0.015mol) was added, and the suspension was stirred for 1 h at room temperature. Dansyl chloride (2.935 g, 0.01mol) dissolved in 30ml DCM was added dropwise with stirring. After reacting for 4h at room temperature, the precipitate was removed by the filtration, and the supernatant was concentrated under the reduced pressure. After evaporation of the solvent, the product was purified by silica gel column chromatography using a mixed solvent of ethyl acetate and hexane (1/1, v/v) as eluent to give the N-[(5-N,N-Dimethylaminonaphthylsulfonylamino)ethyl]-2-methacrylamide(DnsEMA). DnsEMA: 1 H NMR (600 MHz, DMSO-d 6, ppm): δ8.45 (d,1h, naphthyl), δ 8.25 (d, 1H, naphthyl), 8.07 (d, 1H, naphthyl), δ 7.96 (t, 1H, -NH-CO-), δ 7.75 (t, 1H, -SO 2 -NH-),δ7.59 (m, 2H, naphthyl),δ7.23 (d, 2H, naphthyl), δ5.53 (s,1h, olefin), δ 5.24 (s,1h, olefin), δ 3.10 (t, 2H, -CH 2 -NH-CO-),δ2.84 (t, 2H, -CH 2 -NH-SO 2 -), δ 2.81 (s, 6H, -N-(CH 3 ) 2 ). δ1.74 (s,3h, -CH 3 ). - S-3 -

4 Figure S2 1 H NMR Spectrum of DnsEMA. 3 Preparation of polymer samples The dansyl-modified water swellable polymer networks poly((n,n'-methylenediacrylamide)-co-(acrylamide)-co-dnsema were prepared by free radical copolymerization in bulk. The structure were shown in Scheme 1. Scheme S2 Dansyl-modified water-swellable polymer networks. Samples of the different feeding molar ratios given in Table 1 were prepared. General procedure (Dns5-PAAM): a predetermined amount of AAm (227.2 mg, 3.2 mmol), MBA (94.3 mg, 0.6 mmol) and DnsEMA (72.3 mg, 0.2 mmol) were dissolved in DMSO (4 ml). - S-4 -

5 After purging with dry argon for 30 min, AIBN (3.3 mg, 0.02 mmol) was added to the monomer solution. The reaction mixture was placed into a Polytetrafluoroethylene mold and sealed. The mold was set into an oven thermostated at 60 C for 8 h. The gel formed was purified by exposing to DMSO several days and then repeated washing with water to remove DMSO. Figure S3 IR- Spectra of Dns25-PAAM. FTIR (KBr): cm -1 (v N-CH3), cm -1 (ν C=O), cm -1 (ν N-H), cm -1 (vas SO2), cm -1 (vs SO2). 4 Instruments and measurements 4.1 Tensile Strength Test The average dimension of test specimens is cm(length width thick). First, the samples were immersed in the ph 5 (or ph 2) buffer solution for 24 h. Then remove the water on the surface of the film with filter paper. Tensile strength measurements at room temperature were carried out immediately with the wet samples on a universal tensile tester (SANS CMT4104). The strain rate was 50 mm min -1 in all experiments. 4.2 Rheological behavior Test All samples were measured in an oscillation experiment (amplitude sweep) from 10 up to 500 Pa with plate-to-plate geometry at 25 C (±0.25 C). The rheometer was equipped with serrated plates with a diameter of 35 mm. A frequency of 1 Hz was chosen and each sample - S-5 -

6 was measured three times successively with a relaxation time of 1s. Oscillation experiment was carried out on a rheometer (HAAKE MARS). 4.3 Determination of the equilibrium swelling ratio Three disc shaped samples of a kind were immersed into 50 ml in different ph for 3 days. After being taken out of the swelling medium, excess water from each discs surface was removed with a filter paper. The swelling ratio of each sample was determined by the weight ratio Ws/Wp, where Ws is the weight of the absorbed water and Wp is the weight of the dried polymer sample. The given swelling ratios are the arithmetic average of all three measured disc shaped samples. Buffer solution was 0.1M potassium chloride with hydrochloric acid adjust the ph to 1.5 and 2, and disodium hydrogen phosphate-citric acid buffer range from ph 2.5 to ph 8. A PHS-3C digital ph meter was utilized to measure the ph values of aqueous solutions. 4.4 Shape-Memory Experiments ph-responsive shape-memory test According to the method reported by Liu et al., the dual shape-memory effect (SME) of hydrogel based on ph can be measured. The method to evaluate the dual shape-memory property was illustrated in the Scheme S3. Scheme S3 The schematic representation of the dual shape-memory test. - S-6 -

7 First, the straight strip Dns-PAAM hydrogels was deformed with an angleγ(180 in this study) and then immersing in ph 2 buffer solution overnight. Before the external force was removed, this deformation was kept for 30 min in ph 5 buffer solution. After releasing the force, an angle α can be measured by protractor. The shape fixity ratio Rf was calculated as formula(1): Rf=α/180 (S1) To recover to the original shape, the hydrogels was transferred into ph 2 buffer solution, the ultimate angle was recorded as β. The shape recovery ratio Rr was calculated as formula(2): Rr=(α-β)/α (S2) Thermo-responsive shape-memory test The dual shape-memory effect (SME) of hydrogel based on heat can be measured thought the same way. The Dns-PAAM hydrogel was first deformed with an angle 180 at ph 5 buffer solution after heating at 50 C for 5 min. This deformation was kept for 1 min at room temperature before the external force was removed. After releasing the force, an angle α was obtained. Then, the film was heating at 50 C to recover to the original shape, the ultimate angle was recorded as β. The shape fixity ratio Rf and the shape recovery ratio Rr were calculated as formula(1) and (2). 4.5 Dynamic mechanical analysis (DMA) Dynamic mechanical analysis (DMA) was performed using a DMA Q800V7.1 in the strain mode at a fixed frequency of 1 Hz with the temperature range from 5 to 65 C, and a heating rate of 1.0 K min 1 was employed in these measurements. 4.6 Wide-angle X-ray diffraction (WAXD) Wide-angle X-ray diffraction (WAXD) were obtained on a Rigaku Smart lab 3 using Cu K α (1.54 Å) as a target over a scan range of 5-80 with 0.02 step size and 2 min -1 scan speed. - S-7 -

8 Figure S4 WAXD pattens of Dns-PAAM hydrogels with different dansyl molar ratio. Figure S5 The fixity ratio and recovery ratio of thermal-induced shape memory effect of Dns-PAAM hydrogels with different dansyl molar ratio. - S-8 -

9 Figure S6 ph- and thermal-induced shape memory behaviors of Dns25-PAAM. a) Original shape under ph 2 solution in room temperature. b) Temporary spiral shape deformed through ph changing process (ph 2 and ph 5) in room temperature. c) Sample recovered from temporary shape to original shape in buffer solution with ph 5 in hot water (>50 C). d) Sample recovered from the first temporary shape to original shape at 50 C 30 s later. Figure S7 Thermal- and ph- shape memory behaviors of Dns25-PAAM. a) Original shape in deionized water in room temperature. b) Sample was deformed into a S shape through heat process (room temperature and >50 C) in deionized water. c) Sample recovered from temporary shape to original shape in solution with ph 2 in room temperature. - S-9 -