Supporting Information

Transcription

1 Supporting Information UCST or LCST? Composition-Dependent Thermoresponsive Behavior of Poly(N-Acryloylglycinamide-co-Diacetone Acrylamide) Wenhui Sun, Zesheng An*, Peiyi Wu * Experimental Materials Glycinamide hydrochloride (98%, Acros) and acryloyl chloride (96%, Fluka) were used as received. Diacetone acrylamide (DAAM, 99%) and 2,2 -Azobis(2-methylpropionamidine) dihydrochloride (V-50, 97%) were purchased from Sigma-Aldrich. The chain transfer agent (CTA) 2-ethylsulfanylthiocarbonylsulfanyl-propionic acid methyl ester was synthesized according to a previous report. 1 Characterization Turbidity measurements (1 wt%) were carried out at 500 nm on a Lamda 35 UV vis spectrometer with deionized water as reference at a heating/cooling rate of 1 C min -1. Hydrodynamic diameters (D h ) (1 mg ml -1 ) were measured on a Malvern ZS90 at a heating/cooling rate of 1 C min -1 after being allowed to equilibrate at the setting temperatures for 2 min. Molecular weight and dispersity were determined using S1

2 Waters size exclusion chromatography (SEC) equipped with Styragel HR4 and HR5 columns and a Waters 2410 refractive index detector. The measurements were made using DMSO with LiBr (2 mg ml -1 ) as eluent at 70 C column temperature. Prior to the measurements, the samples were allowed to dissolve at 70 C for 2h. Samples soluble in N,N-Dimethylformamide (DMF) were also run using DMF (LiBr, 2 mg ml -1 ), Styragel HR4, HR5, and HR6 columns, column temperature 30 C) as an eluent. The flow rate was 1.0 ml min -1 in all cases. Calibration was made with pullulan standards (Shodex Standard) in DMSO or PMMA standards in DMF. 1 H NMR spectra of the copolymers were recorded on a Varian Mercury plus (500 MHz) spectrometer using D 2 O as the solvent. Varible-temperture 1 H NMR spectra of copolymer solutions were recorded on a Varian Mercury plus (500 MHz) spectrometer using D 2 O as the solvent (concentration = 10 wt%) at an increment or a decrement of 1 o C. FTIR spectra were recorded on a Nicolet Nexus 6700 FTIR spectrometer equipped with a DTGS detector at 25 o C. Synthesis of N-Acryloyl Glycinamide (NAGA) NAGA was synthesized according to the previous reported procedure in literature. 2 Typically, glycinamide hydrochloride (3 g, mmol) and K 2 CO 3 (7.5 g, mmol) were dissolved together in 50 ml of water and cooled in ice bath. Acryloyl chloride (1.975 ml, mmol) dissolved in 100 ml of diethyl ether was added dropwise to the cooled solution under vigorous stirring. The reaction was allowed to proceed at room temperature for 2 h. Diethyl ether was removed and the remaining solution was freeze-dried. The crude solid product was extracted with acetone (6 S2

3 times, 200 ml, 40 C, 15 min). Insoluble potassium salt was filtered off under vacuum and half of the acetone was removed by rotary evaporation at 40 C. The concentrated solution was cooled for several hours at 4 C leading to the formation of white crystals which were filtered and redissolved in minimum amount of methanol: acetone mixture (1:2, v/v) and recrystallized at 4 C. The NAGA crystal was filtered, dissolved in deionized water and freeze-dried. 1 H NMR (500 MHz, D 2 O): δ = 3.92 (s, 2H, N CH 2 CONH 2 ), 5.76 (dd, J(doublet 1) = 2.0 Hz, J(doublet 2) = 9.5 Hz, 1H), 6.19 (dd, J(doublet 1) = 2.0 Hz, J(doublet 2) = 17.1 Hz, 1H), 6.29 (dd, J(doublet 1) = 9.5 Hz, J(doublet 2) = 17.2 Hz, 1H). Synthesis of Poly(N-Acryloyl Glycinamide) (PNAGA) Homopolymer CTA 2-ethylsulfanylthiocarbonylsulfanyl-propionic acid methyl ester (3.6 mg, mmol), NAGA (410 mg, 3.20 mmol) was dissolved in 8.3 ml of water. The solution was degassed with nitrogen at 0 o C for 40 min before immersion into a preheated oil bath at 70 o C. When the temperature was stabilized, a degassed solution of V-50 (0.35 mg, mmol) in water was injected via a microsyringe. After designated time the reaction was stopped by exposing the solution to air and cooling. The polymer PNAGA was purified by extensive dialysis against distilled water and lyophilized. Synthesis of Poly(Diacetone Acrylamide) (PDAAM) Homopolymer CTA 2-ethylsulfanylthiocarbonylsulfanyl-propionic acid methyl ester (3.6 mg, mmol) and DAAM (542 mg, 3.20 mmol) was dissolved in 5.5 ml of DMF. The solution was degassed with nitrogen at 0 o C for 40 min before immersion into a preheated oil bath at 70 o C. When the temperature was stabilized, a degassed solution S3

4 of AIBN (0.21 mg, mmol) in DMF was injected via a microsyringe. After designated time the reaction was stopped by exposing the solution to air and cooling. The polymer PDAAM was purified by extensive dialysis against distilled water and lyophilized. Synthesis of P(NAGA-co-DAAM) Copolymers The total monomer concentration was 10% and the molar ratio of [CTA]/[Mono]/[V-50] was controlled at 1/200/0.08. The target degree of polymerization (DP) was 200, and the actual DP of all thermosensitive copolymers was around 200. The molar ratio of NAGA/DAAM was varied from 99 : 1 to 35: 65. An exemplary synthesis of the copolymers is given for P(NAGA 96 -co-daam 95 ). CTA 2-ethylsulfanylthiocarbonylsulfanyl-propionic acid methyl ester (3.6 mg, mmol), NAGA (205 mg, 1.60 mmol) and DAAM (271 mg, 1.60 mmol) were dissolved in 4.8 ml of water. The solution was degassed with nitrogen at 0 o C for 40 min before immersion into a preheated oil bath at 70 o C. When the temperature was stabilized, a degassed solution of V-50 (0.35 mg, mmol) in water was injected via a microsyringe. After designated time the reaction was stopped by exposing the solution to air and cooling. Aliquots were sampled at predetermined time intervals for polymerization kinetics study. For molar ratios of NAGA/DAAM in the range of 30 : 70 to 5: 95, the copolymerization was conducted in DMSO with AIBN as the initiator. The copolymers were purified by extensive dialysis against distilled water and isolated via lyophilization. The resulting copolymers were named as NAGA-X (X is the monomer in molar percentage). S4

5 Figure S1. 1 H NMR spectrum of NAGA in D 2 O. Figure S2. 1 H NMR spectra of copolymers in D 2 O. S5

6 Table S1 Synthetic Conditions and Results of Copolymers. a polymer Composition code Conv. M n,th (%) b (g/mol) c M n (GPC) d Đ UCST/LCST (g/mol) (GPC) d ( o C) PDAAM PDAAM NAGA5 P(NAGA 10 -co-daam 192 ) NAGA10 P(NAGA 20 -co-daam 178 ) Insoluble NAGA20 P(NAGA 38 -co-daam 162 ) NAGA30 P(NAGA 58 -co-daam 138 ) a Target DP = ~200 b Monomer conversion determined by 1 H NMR. c Theoretical molecular weight of copolymers = (target DP NAGA monomer conversion) M NAGA + (target DP DAAM monomer conversion) M DAAM + M CTA. d Molecular weight determined by GPC (DMF, PMMA). Figure S3. Polymerization kinetics of copolymerization of NAGA50, [Monomer]/[CTA]/[V-50] = 200:1:0.08, concentration = 10%. S6

7 Figure S4. Thermal transitions of UCST-type (co)polymers measured by turbidimetry (a) PNAGA, (b) NAGA99 and (c) NAGA95 (1wt%) during cooling/ heating cycle. Figure S5. Thermal transitions of UCST-type (co)polymers measured by turbidimetry during cooling in D 2 O (1wt%). Figure S6. Thermal transitions of NAGA95 at different concentrations in water measured by turbidimetry. S7

8 Figure S7. Thermal transitions of LCST-type copolymers measured by turbidimetry (a) NAGA45, (b) NAGA50 and (c) NAGA56 (1wt%) during heating /cooling cycle. Figure S8. Thermal transitions of LCST-type copolymers measured by turbidimetry upon heating in D 2 O (1wt%). S8

9 Figure S9. Thermal transitions of NAGA50 at different concentrations in water measured by turbidimetry. Figure S10. Thermal transitions of NAGA50 measured by turbidimetry in PBS solutions (ph = 7.4) (a), and in H 2 O with different ph (1 wt%) (b). S9

10 Table S2 Synthetic Conditions and Results of Copolymers with Different DPs. a polymer Composition code Conv. M n,th (%) b (g/mol) c M n (GPC) d Đ LCST (g/mol) (GPC) d ( o C) e 45 P(NAGA 23 -co-daam 22 ) P(NAGA 44 -co-daam 48 ) P(NAGA 143 -co-daam 145 ) P(NAGA 196 -co-daam 192 ) P(NAGA 243 -co-daam 242 ) a [Mono] = 0.67 M, NAGA: DAAM = 1:1, Monomer: V-50 = 200:0.08, 70 o C b Monomer conversion determined by 1 H NMR. c Theoretical molecular weight of copolymers = (target DP NAGA monomer conversion) M NAGA + (target DP DAAM monomer conversion) M DAAM + M CTA. d Molecular weight determined by GPC (DMF, PMMA). e The temperature at 50% transmittance of the thermal transition was taken as the LCST. Figure S11. Variable-temperature 1 H NMR spectra of (a) NAGA90 in D 2 O upon cooling and (b) NAGA50 in D 2 O upon heating. (1) Xu, Y. Y.; Li, Y. C.; Cao, X. T.; Chen, Q. J.; An, Z. S., Versatile RAFT dispersion polymerization in cononsolvents for the synthesis of thermoresponsive nanogels with controlled composition, functionality and architecture. Polym. Chem. 2014, 5 (21), (2) Seuring, J.; Bayer, F. M.; Huber, K.; Agarwal, S., Upper Critical Solution Temperature of Poly(N-acryloyl glycinamide) in Water: A Concealed Property. Macromolecules 2012, 45 (1), S10

11 S11