Sequence-controlled methacrylic multiblock. copolymers via sulfur-free RAFT emulsion. polymerization

Transcription

1 DOI: /NCHEM.2634 Sequence-controlled methacrylic multiblock copolymers via sulfur-free RAFT emulsion polymerization Nikolaos G. Engelis a, Athina Anastasaki* a,b,gabit Nurumbetov a, Nghia P. Truong b, Vasiliki Nikolaou a, Ataulla Shegiwal a, Michael R. Whittaker b, Thomas P. Davis* b and David M. Haddleton* a,b a - University of Warwick, Chemistry Department, Library road, CV4 7AL, Coventry, United Kingdom. b - ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University (Parkville Campus), 399 Royal Parade, Parkville, Victoria 3152, Australia These authors contributed equally to this work. Table of contents 1.Materials/Instrumentation 2.Synthetic protocols 3.Supplementary tables and figures 4.Supplementary references p2 p3 p4 p18 NATURE CHEMISTRY 1

2 Section A. Materials / Instrumentation All reagents were purchased from Sigma-Aldrich or MP Biomedicals and used without further purification unless otherwise stated. Bis[(difluoroboryl) dimethylglyoximato]cobalt(ii) (CoBF) was synthesised according to the procedure of Espenson. 4,4 -Azobis cyanovaleric acid (CVA) was employed for the synthesis of the initial PMMA macromonomer while potassium persulfate was used for all chain extension reactions. Sodium dodecyl sulphate (SDS) was employed as surfactant. Deionised water (RO grade) was used in all reactions. Instrumentation. 1 H NMR spectra were recorded on Bruker DPX-300 and HD-400 spectrometers using a mixture of deuterated chloroform and deuterated acetone (v/v=3:2), both obtained from Aldrich. Chemical shifts are given in ppm downfield from the internal standard tetramethylsilane. Size exclusion chromatography (SEC) measurements were conducted using an Agilent 1260 GPC- MDS fitted with differential refractive index (DRI), light scattering (LS) and viscometry (VS) detectors equipped with 2 x PLgel 5 mm mixed-d columns (300 x 7.5 mm), 1 x PLgel 5 mm guard column (50 x 7.5 mm) and autosampler. Narrow linear poly(methyl methacrylate) standards in range of x 10 6 g mol -1 were used to calibrate the system. All samples were passed through 0.45 μm PTFE filter before analysis. The mobile phase was chloroform with 2% triethylamine at a flow rate of 1.0 ml/min. SEC data were analysed using Cirrus v3.3. Matrix-assisted laser desorption ionization mass spectrometry (MALDI-ToF-MS) was conducted using a Bruker Daltonics Ultra flex II MALDI- ToF-MS mass spectrometer, equipped with a nitrogen laser delivering 2 ns laser pulses at 337 nm with positive ion ToF detection performed using an accelerating voltage of 25 kv. Solutions in tetrahydrofuran (50 μl) of 2,5-dihydroxybenzoic acid (DHB) as matrix (saturated solution), sodium iodide as cationization agent (1.0 mg/ml), and sample (1.0 mg/ml) were mixed, and 0.7 μl of the mixture was applied to the target plate. Spectra were recorded in reflector mode calibrating PEG-Me 1100 kda. DLS measurements were performed on a Malvern instrument Zetasizer Nano Series instrument with a detection angle of 173, where the intensity weighted mean hydrodynamic size (Zaverage) and the width of the particle size distribution were obtained from analysis of the NATURE CHEMISTRY 2

3 autocorrelation function. 1μL of latex was diluted with 1 ml of deionized water previously filtered with 0.20 μm membrane to ensure the minimization of dust and other particulates. At least 3 measurements at 25 C were made for each sample with an equilibrium time of 2 min before staring measurement. Section B. Synthetic Protocols 1) PMMA Macromonomer Synthesis In a typical CCTP in emulsion, CoBF (7.5 mg) was placed in a 100 ml round bottom flask together with a stirring bar. Nitrogen was purged in the flask for at least 1h. Subsequently, MMA (20 ml, g, mmol) previously degassed for 30 min was to the flask via a degassed syringe. The mixture was vigorously stirred under inert atmosphere until total dissolution of the catalyst. Meanwhile, CVA (0.5 g, mmol), SDS (0.3 g, mmol) and 130 ml of water were charged into a three-neck, 500 ml double jacketed reactor, equipped with a RTD temperature probe and an overhead stirrer. The mixture was purged with nitrogen and stirred at 325 rpm for at least 30 min. Subsequently, the mixture was heated under inert atmosphere. When the temperature in the reactor reached 70 C, the addition of the MMA-CoBF solution started using a degassed syringe and a syringe pump (feeding rate=0.666 ml/min, feeding time=30 min). When the addition was over, stirring continued for another 30 min under the same conditions. Subsequently, the heat pump settings were adjusted to 107 C and stirring continued for 60 min enabling the reaction to stay at C. 2) PMMA-b-PBMA Diblock Copolymer Synthesis In a typical chain extension aiming for DP=10 for the BMA block, 125 ml of PMMA macromonomer latex were diluted by adding 37 ml of water to achieve a 10% solid content. The resulting latex was charged in the reactor and purged with nitrogen for 30 min under stirring. Subsequently, the emulsion was heated. When the temperature in the reactor reached C and was stabilised, the simultaneous addition of BMA (15.9 ml, g, 0.1 mol) and potassium persulfate aqueous solution (79.53 mg potassium persulfate in 15.9 ml of water), both previously degassed for 30 min started by the use of degassed syringes and a syringe pump (feeding rate=0.16 NATURE CHEMISTRY 3

4 ml/min, feeding time=100 min). When the addition was over, stirring continued for another 60 min under the same conditions. For all the chain extension reactions the same process was followed, each time adjusting the monomer and potassium persulfate aqueous solution quantities according to the desired degree of polymerisation. Section C. Tables and Figures Supplementary Figure 1. 1 H NMR trace of the of the PMMA macromonomer obtained via CCT in emulsion polymerisation. NATURE CHEMISTRY 4

5 Intensity m/z Observed mass [Na + ]: Expected mass [Na + ]: Intensity m/z Supplementary Figure 2. MALDI spectra of the of the PMMA macromonomer obtained via CCT in emulsion polymerisation. NATURE CHEMISTRY 5

6 Supplementary Figure 3. Proposed mechanisms of CCTP and addition-fragmentation reaction. 1, 2 NATURE CHEMISTRY 6

7 Supplementary Figure 4. Typical set up for the synthesis of macromonomers or multiblock copolymers employing a double jacketed reactor and securing a constant monomer addition rate by the use of a syringe pump. Supplementary Table 1. Experimental conditions used for the preparation of the tetracosablock BMA homopolymer in emulsion at 85 C with potassium persulfate as initiator Entry Cycle M DP targeted mmonomer (g) MCTA (g) mkps VH2O Vtotal (ml) [a] S.C. (g/ml) % wt solids (mg) (ml) 1 2 BMA BMA BMA BMA BMA b BMA BMA BMA BMA BMA BMA c BMA BMA NATURE CHEMISTRY 7

8 14 15 BMA BMA BMA BMA d BMA BMA BMA BMA BMA BMA [a]: after the end of each cycle, a sample of 5 ml was taken. The amount of CTA removed from the system was taken into account for the calculations of the next cycle [b]: 70 ml of the latex of cycle 6 were diluted to 10 % wt of solids by adding ml of H 20 [c]: 180 ml of the latex of cycle 12 were diluted to 10 % wt of solids by adding ml of H 20 [d]: 200 ml of the latex of cycle 18 were diluted to 10 % wt of solids by adding 73.6 ml of H 20 Supplementary Table 2. Characterisation data for the synthesis of the tetracosablock BMA homopolymer in emulsion at 85 C with potassium persulfate as initiator Entry Cycle Conv. a Mn,th Mn,SEC Size b ÐSEC (%) (g/mol) (g/mol) (nm) ÐDLS 1 CTA >99 1,800 2, >99 3,200 3, >99 4,600 4, >99 6,000 6, >99 7,400 7, >99 8,800 9, >99 10,200 10, >99 11,600 11, >99 13,000 12, >99 14,400 13, >99 15,800 15, >99 17,200 16, >99 18,600 17, >99 20,000 18, >99 21,400 20, >99 22,800 21, >99 24,200 23, >99 25,600 24, >99 27,000 25, >99 28,400 26, >99 29,800 27, >99 31,200 28, NATURE CHEMISTRY 8

9 23 22 >99 32,600 29, >99 34,000 30, wdlogm M (g/mol) Supplementary Figure 5. SEC traces of the of the tetracosablock BMA homopolymer (ppm) Supplementary Figure 6. 1 H NMR traces of the of the tetracosablock BMA homopolymer. NATURE CHEMISTRY 9

10 450 Hydrodynamic Diameter (nm) M (g/mol) Supplementary Figure 7. Evolution of the hydrodynamic diameter of the tetracosablock BMA homopolymer, as obtained by Z-average measurements, along with the corresponding numberaverage molecular weight values. M w /M n M (g/mol) CTA (a) (b) Number of cycles Supplementary Figure 8. a) Evolution of theoretical (black straight line) and experimental molecular weight M n ( ) and M w ( ) determined by SEC b) M w/m n ( ) versus the number of cycles during synthesis of tetracosablock homopolymer. NATURE CHEMISTRY 10

11 CTA Monomer b a d c (ppm) Supplementary Figure 9. 1 H NMR traces of the of the PMMA macromonomer obtained via CCT in emulsion polymerisation and the residual MMA monomer. Entry Supplementary Table 3. Experimental conditions used for the preparation of the tetracosablock copolymer in emulsion at 85 C with potassium persulfate as initiator Cycle Monom er DP targeted M monomer (g) MCTA (g) mkps VH2O Vtotal (ml) [a] S.C. (g/ml) % wt solids (mg) (ml) 1 2 BMA BzMA b EHMA BMA BzMA c EHMA BMA BzMA d EHMA BMA BzMA EHMA BMA BzMA e EHMA BMA BzMA EHMA BMA BzMA f EHMA BMA BzMA NATURE CHEMISTRY 11

12 [a]: after the end of each cycle, a sample of 5 ml was taken. The amount of CTA removed from the system was taken into account for the calculations of the next cycle [b]: 60 ml of the latex of cycle 3 were diluted to 10 % wt of solids by adding 69.6 ml of H 20 [c]: 55 ml of the latex of cycle 6 were diluted to 10 % wt of solids by adding ml of H 20 [d]: 70 ml of the latex of cycle 9 were diluted to 10 % wt of solids by adding ml of H 20 [e]: 70 ml of the latex of cycle 15 were diluted to 10 % wt of solids by adding ml of H 20 [f]: 70 ml of the latex of cycle 21 were diluted to 10 % wt of solids by adding ml of H 20 Supplementary Table 4. Characterisation data for the synthesis of the tetracosablock copolymer in emulsion at 85 C with potassium persulfate as initiator Entry Cycle Conv. a M n,th M n,sec Size b ÐSEC (%) (g/mol) (g/mol) (nm) ÐDLS 1 CTA >99 2,000 2, ,400 3, ,200 5, >99 7,200 6, ,600 7, ,400 9, >99 12,400 10, >99 13,800 11, ,600 12, >99 17,600 13, ,000 14, ,800 16, >99 22,800 17, >99 24,200 18, >99 26,000 20, >99 28,000 21, ,400 22, >99 31,200 24, >99 33,200 25, >99 34,600 28, >99 36,400 29, >99 38,400 30, >99 39,800 31, >99 41,600 33, NATURE CHEMISTRY 12

13 400 Hydrodynamic Diameter (nm) M (g/mol) Supplementary Figure 10. Evolution of the hydrodynamic diameter of the tetracosablock copolymer blocks, as obtained by Z-average measurements, along with their corresponding number-average molecular weight. 98% 99% 99% 99% 99% 99% 99% 99% 99% (ppm) Supplementary Figure H NMR traces of the of the tetracosablock copolymer blocks. NATURE CHEMISTRY 13

14 1.0 wdlogm M (g/mol) Supplementary Figure 12. SEC traces of the of the tetracosablock copolymer blocks M w /M n Number of cycles Supplementary Figure 13. Dispersity (Ð) as a function of the number of cycles for the tetracosablock copolymer NATURE CHEMISTRY 14

15 Supplementary Table 5. Experimental conditions used for the preparation of the heptablock copolymer in emulsion at 85 C with potassium persulfate as initiator Entry Cycle M DP m monomer (g) M CTA m KPS V H2O V total (ml) [a] S.C. (g/ml) % wt solids (g) (mg) (ml) 1 2 b BMA c BzMA d EHMA BMA BzMA EHMA [a]: after the end of each cycle, a sample of 5 ml was taken. The amount of CTA removed from the system was taken into account for the calculations of the next cycle [b]: 100 ml of the latex of cycle 1 were diluted by adding 70 ml of H 20 [c]: 100 ml of the latex of cycle 2 were diluted by adding ml of H 20 [d]: 150 ml of the latex of cycle 3 were diluted to 10 % wt of solids by adding ml of H 20 Supplementary Table 6. Characterisation data for the synthesis of the heptablock copolymer in emulsion at 85 C with potassium persulfate as initiator Entry Cycle Conv. a Mn,th Mn,SEC Size b ÐSEC (%) (g/mol) (g/mol) (nm) ÐDLS 1 CTA 100 1,800 2, ,200 7, ,100 16, ,000 22, ,400 27, >99 39,300 33, ,200 41, NATURE CHEMISTRY 15

16 100% 100% 99% 100% 99% 99% (ppm) Supplementary Figure H NMR traces of the of the heptablock copolymer blocks. 450 Hydrodynamic Diameter (nm) M (g/mol) Supplementary Figure 15. Evolution of the hydrodynamic diameter of the heptablock copolymer blocks, as obtained by Z-average measurements, along with their corresponding number-average molecular weight. NATURE CHEMISTRY 16

17 Supplementary Table 7. Experimental conditions used for the preparation of the undecablock copolymer in emulsion at 85 C with potassium persulfate as initiator Cycle Monomer DP targeted m monomer (g) M CTA m KPS V H2O V total (ml) [a] S.C. (g/ml) % wt solids (g) (mg) (ml) 2 BMA BzMA EHMA b BMA EHMA EHMA BzMA c BzMA BMA BMA [a]: after the end of each cycle, a sample of 5 ml was taken. The amount of CTA removed from the system was taken into account for the calculations of the next cycle [b]: 60 ml of the latex of cycle 4 were diluted to 10 % wt of solids by adding ml of H 20 [c]: 50 ml of the latex of cycle 8 were diluted to 10 % wt of solids by adding ml of H 20 Supplementary Table 8. Characterisation data for the synthesis of the undecablock copolymer in emulsion at 85 C with potassium persulfate as initiator Entry Cycle Conv. a Mn,th Mn,SEC Size b ÐSEC (%) (g/mol) (g/mol) (nm) ÐDLS 1 CTA >99 2,000 2, ,700 3, ,500 5, ,500 8, >99 10,800 11, >99 15,800 14, >99 21,700 18, ,900 23, ,600 29, >99 37,000 34, >99 44,100 42, NATURE CHEMISTRY 17

18 M w /M n Number of cycles Supplementary Figure 16. Dispersity (Ð) as a function of the number of cycles for the undecablock copolymer 600 Hydrodynamic Diameter (nm) M (g/mol) Supplementary Figure 17. Evolution of the hydrodynamic diameter of the undecablock copolymer blocks, as obtained by Z-average measurements, along with their corresponding number-average molecular weight. Supplementary references 1. Suddaby, K. G., Haddleton, D. M., Hastings J. J., Richards S. N. & O'Donnell J. P. Catalytic Chain Transfer for Molecular Weight Control in the Emulsion Polymerization of Methyl Methacrylate and Methyl Methacrylate-Styrene. Macromolecules 29, (1996). NATURE CHEMISTRY 18

19 2. Krstina, J. et al. Narrow Polydispersity Block Copolymers by Free-Radical Polymerization in the Presence of Macromonomers. Macromolecules 28, (1995). NATURE CHEMISTRY 19