Supporting Information

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1 Supporting Information Photoinduced Oxygen Reduction for Dark Polymerization Sivaprakash Shanmugam, a Jiangtao Xu, a,b and Cyrille Boyer a,b * a- Centre for Advanced Macromolecular Design (CAMD), School of Chemical Engineering, UNSW Australia, Sydney, NSW 2052, Australia b- Australian Centre for NanoMedicine, School of Chemical Engineering, UNSW Australia, Sydney, NSW 2052, Australia EXPERIMENTAL SECTION Materials: Oligo(ethylene glycol) methyl ether methacrylate (OEGMA, average M n 300), N,Ndimethylacrylamide (DMA, 99%), N-isopropylacrylamide (NIPAAM), 2-hydroxyethyl acrylate (HEA), oligo(ethylene glycol) methyl ether acrylate (OEGA 480 ), 4,5,6,7-Tetrachloro-2,4,5,7 -tetraiodofluorescein sodium salt (Rose Bengal-RB) and 2,4,5,7 -Tetrabromofluorescein disodium salt (Eosin Y-EY) were all purchased from Aldrich. N,N-diethylacrylamide (DEA, 98%) was purchased from Tokyo Chemical Industry (TCI). Deinhibition of monomers was carried out by percolating over a basic alumina column (Ajax Chemical, AR). Milli-Q water was obtained from arium pro Ultrapure Water Systems (Sartorius). Thiocarbonylthiol compound: 4-cyanopentanoic acid dithiobenzoate (CPADB), and 2-(n-butyltrithiocarbonate)-propionic acid (BTPA) were synthesized according to literature procedures 1 and 4-((((2-carboxyethyl)thio)carbonothioyl)thio)- 4-cyanopentanoic acid (CETCPA) was purchased from Boron Molecular. Instrumentation: Gel Permeation Chromatography (GPC) was used for characterization of synthesized polymer with N,Ndimethylacetamide (DMAc). The DMAC instrument consists of Shimadzu modular system with an autoinjector, a Phenomenex 5.0 µm bead sizeguard column (50 x 7.5 mm) followed by four Phenomenex 5.0 µm bead size S1

2 columns (10 5, 10 4, 10 3 and 10 2 Å) and a differential refractive-index detector and a UV detector (λ = 305 nm). DMAc GPC was calibrated based on narrow molecular weight distribution of polystyrene and polymethyl methacrylate standards with molecular weights of 200 to 10 6 g mol -1. Nuclear Magnetic Resonance (NMR) spectroscopy was carried out with Bruker Avance III HD operating at 300, 400 and 600 MHz for 1 H using CDCl 3, DMSO-d 6, MeOD and D 2 O as solvent. Tetramethylsilane (TMS) was used as a reference with chemical shift (δ) of sample measured in ppm downfield from TMS. On-line Fourier Transform Near-Infrared (FTNIR) was used to determine monomer conversion by mapping the decrease in the integration of the vinylic C-H stretching overtone of monomer at ~ 6200 cm -1. A Bruker IFS 66/S Fourier transform spectrometer equipped with a tungsten halogen lamp, a CaF 2 beam splitter and liquid nitrogen cooled InSb detector was used. Polymerizations different wavelengths of visible light were carried out using FT-NIR quartz cuvette (1 cm 2 mm). Each spectrum composed of 16 scans with a resolution of 4 cm -1 was collected in the spectral region between cm -1 by manually placing the sample in the sample holder during periods of irradiation. For measurements during the dark period, the cuvette is left in the sample holder and scans were carried out in automation where 1 scan is taken every 15 minutes for a period of 9-12 hours. The total collection time per spectrum was about 15 seconds and analysis was carried out with OPUS software. ph/ion meter. ph measurements of reaction mixtures were carried out using Mettler Toledo SevenCompact ph meter calibrated to standard ph buffers. UV-vis Spectroscopy. UV-vis spectra were recorded using a CARY 300 spectrophotometer (Varian) equipped with a temperature controller. Fluorescence spectroscopy. Fluorescence spectra were recorded using Agilent fluorescent spectrometer. Solar Simulator: Oriel VeraSol LED solar simulator consisting of the LSS-7120 LED controller and LSH-7520 LED head was used as the light source for different wavelength irradiation. S2

3 General Procedures for Kinetic Studies of Dark Polymerization of N,N-dimethylacrylamide (DMA) with Online Fourier Transform Near-Infrared (FTNIR) Spectroscopy with Rose Bengal (RB) with Initial Irradiation of 45 minutes For reaction in the presence of [DMA]:[BTPA]:[RB]:[Asc acid] of 200 : 1 : : 1, a reaction stock solution consisting of Milli-Q water (337 µl), DMA (432 µl, g, mmol), BTPA (5.0 mg, MW: g/mol), RB (MW: g/mol, 82 µl of mm of RB stock solution in water, µmol), and ascorbic acid (MW: g/mol, 3.7 mg, mmol) was prepared in a 1 ml FTNIR quartz cuvette (1 cm 2 mm) covered in aluminum foil. Polymerization was carried out at 20 ppm catalyst concentration which is the molar ratio between [RB] : [DMA] and 4.9 M monomer concentration. No nitrogen sparging was carried out. The cuvette with the reaction mixture was then irradiated under yellow LED light (λ max = 560 nm, intensity = 8 mw/cm 2 ) at room temperature (~25 C). The cuvette was transferred to a sample holder manually for FTNIR measurements every 15 minutes for 45 min irradiation period. After 15 seconds of scanning, the cuvette was transferred back to the light source. Monomer conversions were calculated by taking the ratio of integrations of the wavenumber area cm -1 for all curves at different reaction times to that of 0 minutes. After 45 min irradiation, the cuvette with the reaction mixture was placed in the sample holder in complete darkness and 60 scans were taken in automation with a delay of 15 minutes between each scan. Care was taken to not agitate or shake the cuvettes as the air in the headspace may result in inhibition to polymerization upon mixing with the reaction solution. The reaction sample at the end of the kinetic run was analyzed by GPC (DMAc) to determine number average molecular weights (M n ) and polydispersities (M w /M n ). A similar procedure was repeated for polymerization of Eosin Y with DMA. These procedures were also repeated to study the effects of catalyst and ascorbic acid concentrations by simple manipulation of ratio of these two components in the reaction mixture. In addition, for experiments with continuous irradiation of reaction mixture, similar procedure was followed with the exception of continuously irradiating the reaction mixture throughout the reaction. S3

4 General Procedures for Synthesis and Chain Extensions of poly(n,n-dimethylacrylamide) (polydma) macromolecular chain transfer agent (macro-cta) with Different Monomers and Photocatalysts Synthesis of PDMA macro-cta was carried with [DMA]:[BTPA]:[EY]:[Asc acid] in the ratio of 200 : 1 : : 0.1, a reaction stock solution consisting of Milli-Q water (1095 µl), DMA ( ml, g, mmol), BTPA (15.0 mg, MW: g/mol), EY (MW: g/mol, 165 µl of mm of EY stock solution in water, µmol), and ascorbic acid (MW: g/mol, 1.11 mg, mmol) was prepared in a 3 ml FTNIR quartz cuvette (1 cm 1 cm) covered in aluminum foil. Polymerization was carried out at 20 ppm catalyst concentration which is the molar ratio between [EY] : [DMA] and 4.9 M monomer concentration. No nitrogen sparging was carried out. The cuvette with the reaction mixture was then irradiated under green LED light (λ max = 530 nm, intensity = 4 mw/cm 2 ) at room temperature (~25 C). The cuvette was transferred to a sample holder manually for FTNIR measurements every 10 minutes for 20 min irradiation period. After 15 seconds of scanning, the cuvette was transferred back to the light source. Monomer conversions were calculated by taking the ratio of integrations of the wavenumber area cm -1 for all curves at different reaction times to that of 0 minutes. After 20 min irradiation, the cuvette with the reaction mixture was placed in the sample holder in complete darkness and scans were taken in automation for 9 hours. Care was taken to not agitate or shake the cuvettes as the air in the headspace may result in inhibition to polymerization upon mixing with the reaction solution. The reaction sample was analyzed by GPC (DMAc) to determine number average molecular weights (M n ) and polydispersities (M w /M n ) after 9 hours: (α = 99%, M n,theo = g/mol, and M n,gpc = g/mol, M w /M n = 1.06). The macroinitator was then purified by dialysis against methanol for three days. The final product was dried in a 40 C vacuum oven for 24 hours. 1 H analysis was then carried out to determine the presence of RAFT end group. The macroinitator was then chain extended with DMA and NIPAAM using RB under 20 min yellow light irradiation followed by 3 hours in darkness. For DMA, chain extension was carried out with a molar ratio S4

5 of [monomer]:[macro-cta]:[rb]:[asc acid] of 500: 1 : : 1 using 8 ppm catalyst with Milli-Q water (457 µl), DMA ( ml, g, mmol), macrocta (100.0 mg, MW: g/mol), RB (MW: g/mol, µl of mm of RB stock solution in water, µmol), and ascorbic acid (MW: g/mol, 0.84 mg, mmol) was prepared in a 1 ml FTNIR quartz cuvette (2 mm 1 cm) covered in aluminum foil. Chain extension with NIPAM was carried out with a molar ratio of [monomer]:[macro- CTA]:[RB]:[Asc acid] of 200: 1 : : 1 using 40 ppm catalyst with Milli-Q water (881 µl), NIPAM (0.108 g, mmol), macrocta (100.0 mg, MW: g/mol), RB (MW: g/mol, 40 µl of mm of RB stock solution in water, µmol), and ascorbic acid (MW: g/mol, 0.84 mg, mmol) was prepared in a 1 ml FTNIR quartz cuvette (2 mm 1 cm) covered in aluminum foil. Both chain extensions were irradiated for 20 min under yellow light irradiation before placing in the dark for 3 hours. Final monomer conversions were determined with FTNIR for DMA and 1 H NMR for NIPAM with the molecular weight and molecular weight distributions determined by GPC (M n,gpc = g/mol, M w /M n = 1.10 and 50% DMA monomer conversion for PDMA-block-PDMA and M n,gpc = g/mol, M w /M n = 1.07 and 73% NIPAAM monomer conversion for PDMA-block-PNIPAM). General Procedures for UV-Vis Studies of RAFT Photopolymerization of N,N-dimethylacrylamide (DMA) Samples for UV-Vis measurements were prepared in a similar fashion as the preparation of reaction mixture stock solution in a 1 ml FTNIR quartz cuvette (1 cm 2 mm) as described above. Measurements were taken without any degassing. Formulations for the different UV-Vis measurements carried out are listed below based on the Figures in the paper and SI. Figure 8A [EY]:[DMeA]:[Asc acid] = 1 : 0.8: 2.6 with DMAc (3.456 ml), Milli-Q water (0.264 ml), EY (MW: g/mol, 440 µl of mm of EY stock solution in water, µmol), 9,10- dimethylanthracene (DMeA) (MW: g/mol, 0.35 mg, mmol), and ascorbic acid (MW: S5

6 g/mol, 2.96 mg, mmol). About 0.8 ml of the mixture was transferred to the quartz cuvette and irradiation was carried out for the length of time described. Figure 8D [EY]:[DMeA]:[Asc acid] = 1 : 0.8: 2.6 with DMAc (3.456 ml), Milli-Q water (0.264 ml), EY (MW: g/mol, 440 µl of mm of EY stock solution in water, µmol), 9,10- dimethylanthracene (DMeA) (MW: g/mol, 0.35 mg, mmol), and ascorbic acid (MW: g/mol, mg, mmol). About 0.8 ml of the mixture was transferred to the quartz cuvette and irradiation was carried out for the length of time described. SI, Figure S18 - [EY]:[DMeA] = 1 : 0.8 with DMAc (3.456 ml), Milli-Q water (0.56 ml), EY (MW: g/mol, 440 µl of mm of EY stock solution in water, µmol), and 9,10-dimethylanthracene (DMeA) (MW: g/mol, 0.35 mg, mmol). About 0.8 ml of the mixture was transferred to the quartz cuvette and irradiation was carried out for the length of time described. SI, Figure S19 - [DMA]:[RB]:[DMeA]:[Asc acid] = 2000 : 0.08 : 0.2 : 1 with Milli-Q water (683 µl), DMA (1.728 ml, g, mmol), RB (MW: g/mol, 656 µl of mm of RB stock solution in water, µmol), 9,10-dimethylanthracene (DMeA) (MW: g/mol, 0.35 mg, mmol), and ascorbic acid (MW: g/mol, 1.48 mg, mmol). About 0.8 ml of the mixture was transferred to the quartz cuvette and irradiation was carried out for the length of time described. SI, Figure S20 - [DMA]:[EY]:[DMeA]:[Asc acid] = 2000 : 0.04 : 0.2 : 1 with Milli-Q water (1.119 ml), DMA (1.728 ml, g, mmol), EY (MW: g/mol, 220 µl of mm of EY stock solution in water, µmol), 9,10-dimethylanthracene (DMeA) (MW: g/mol, 0.35 mg, mmol), and ascorbic acid (MW: g/mol, 1.48 mg, mmol) prepared in a 3 ml glass vial. About 0.8 ml of the mixture was transferred to the quartz cuvette and irradiation was carried out for the length of time described. S6

7 Polymerization of DMA with Addition of Different Volumes of Air Polymerization of DMA with different volumes of air was carried out with [DMA]:[BTPA]:[EY]:[Asc acid] in the ratio of 200 : 1 : : 0.1, a reaction stock solution consisting of Milli-Q water (1095 µl), DMA ( ml, g, mmol), BTPA (15.0 mg, MW: g/mol), EY (MW: g/mol, 165 µl of mm of EY stock solution in water, µmol), and ascorbic acid (MW: g/mol, 1.11 mg, mmol) was prepared in a 3 ml FTNIR quartz cuvette (1 cm 1 cm) covered in aluminum foil. Polymerization was carried out at 20 ppm catalyst concentration which is the molar ratio between [EY] : [DMA] and 4.9 M monomer concentration. The reaction mixture was sparged under nitrogen for 50 minutes for complete removal of air. Different volumes of air was then added at a rate of 0.1 ml every 10 seconds while making sure that the headspace of the cuvette is constantly flushed with nitrogen to prevent atmospheric air from diffusing into the solution while the addition is carried out. The cuvette with the reaction mixture was then irradiated under green LED light (λ max = 530 nm, intensity = 4 mw/cm 2 ) at room temperature (~25 C). The cuvette was transferred to a sample holder manually for FTNIR measurements every 10 minutes for 20 min irradiation period. After 15 seconds of scanning, the cuvette was transferred back to the light source. Monomer conversions were calculated by taking the ratio of integrations of the wavenumber area cm -1 for all curves at different reaction times to that of 0 minutes. After 20 min irradiation, the cuvette with the reaction mixture was placed in the sample holder in complete darkness and scans were taken in automation for 9 hours. Care was taken to not agitate or shake the cuvettes as the air in the headspace may result in inhibition to polymerization upon mixing with the reaction solution. The reaction sample was analyzed by GPC (DMAc) to determine number average molecular weights (M n ) and polydispersities (M w /M n ) after 9 hours. As the addition of 5 ml of air into the reaction mixture does not correspond to 5 ml of air in the solution as air bubbles out of the solution during addition, parallel singlet oxygen quenching experiment is carried out to have a rough estimation of the amount of oxygen that is trapped in the solution. The composition of the reaction S7

8 mixture for singlet oxygen quenching was similar to the actual reaction mixture for polymerization except that BTPA was not added and ascorbic acid was replaced with 9,10-dimethylanthracene (DMeA), singlet oxygen trapper. 2 The different components for singlet oxygen trapping consist of Milli-Q water (1095 µl), DMA (1.297 ml, g, mmol), EY (MW: g/mol, 165 µl of mm of EY stock solution in water, µmol), and 9,10-dimethylanthracene (DMeA) (MW: g/mol, 0.13 mg, mmol) prepared in a 3 ml FTNIR quartz cuvette (1 cm 1 cm) covered in aluminum foil. The reaction mixture was sparged under nitrogen for 50 minutes for complete removal of air. Different volumes of air was then added at a rate of 0.1 ml every 10 seconds while making sure that the headspace of the cuvette is constantly flushed with nitrogen to prevent atmospheric air from diffusing into the solution while the addition is carried out. An initial UV-Vis scan was obtained to determine the absorption of DMeA at 380 nm before irradiation (A 0 min,380nm). In addition, simultaneous FTNIR measurements were also carried to make sure that the recorded quenching of DMeA at 380 nm is due to singlet oxygen quenching and not quenching from propagating radicals. Irradiation under green light was carried out for every 5 minutes for the different volumes of injected air and stopped upon observing 1-2% monomer conversion as this indicated that singlet oxygen has been completely quenched which allowed for polymerization to commence. The amount of oxygen injected in different volumes of air was determined by: [(A 0 min,380nm A x min,380nm ) / A 0 min,380nm ] mmol (no of moles of DMeA). General Procedure for Nuclear Magnetic Resonance (NMR) Spectroscopy of Hydrogen Peroxide Formation from Reaction Between Singlet Oxygen and Ascorbic Acid/Sodium Ascorbate in the Presence of Eosin Y or Rose Bengal A reaction stock solution consisting of Milli-Q water (0.796 ml), ascorbic acid ( g/mol, 0.37 mg) and EY (MW: g/mol, 55 µl of mm of EY stock solution in water, µmol), was prepared in a glass vial covered in aluminum foil. The reaction mixture was then transferred to a 2 ml glass vial followed by sealing with a septum. The glass vial with the reaction mixture was then irradiated under green light (λ max = 530 S8

9 nm, 4 mw/cm 2 ) at room temperature (~25 C) for 20 minutes. About 100 µl of the reaction mixture was transferred to 500 µl of DMSO-d6 for analysis with Bruker Avance III 600 MHz Cryo NMR. The presence of hydrogen peroxide (H 2 O 2 ) was detected by cooling the sample down to -15 C and compared with a standard hydrogen peroxide (H 2 O 2, %) from a commercial source. These steps were repeated by using RB as the singlet oxygen generator. In addition, ascorbic acid was also replaced with sodium ascorbate and tested with EY and RB. The formulations for these reactions are shown below. Rose Bengal with ascorbic acid: Milli-Q water (0.769 ml), ascorbic acid ( g/mol, 0.37 mg) and RB (MW: g/mol, 82 µl of mm of RB stock solution in water, µmol). Eosin Y with sodium ascorbate: Milli-Q water (0.796 ml), sodium ascorbate ( g/mol, 0.42 mg) and EY (MW: g/mol, 55 µl of mm of EY stock solution in water, µmol) Rose Bengal with sodium ascorbate: Milli-Q water (0.769 ml), sodium ascorbate ( g/mol, 0.42 mg) and RB (MW: g/mol, 82 µl of mm of RB stock solution in water, µmol). Procedure for Hydroxyl Radical Detection A reaction stock solution consisting of Milli-Q water (5.408 ml), sodium ascorbate ( g/mol, mg), EY (MW: g/mol, 664 µl of mm of EY stock solution in water, µmol), and terephthalic acid (MW: g/mol, 0.65 mg) was prepared in a 5mL glass vial. Sodium ascorbate was used instead of ascorbic acid in order to increase the solubility of terephthalic acid as the latter increases ph of the solution to ~ ph Irradiation under green light was carried for 6 hours to maximize the conversion of terephtalic acid to 2-hydroxyterephthalate. The reaction mixture (2 ml) was transferred to a fluorescent cuvette and measurements were then taken with excitation wavelength of λ exc = 312 nm and emission wavelength of λ emm = nm. Measurements were repeated using RB with the following formulation: Milli-Q water (5.408 ml), sodium ascorbate ( g/mol, mg) and RB (MW: g/mol, ml of mm of RB stock solution in water, µmol), and terephthalic acid (MW: g/mol, 0.55 mg). S9

10 General Procedures for UV-Vis Studies of RAFT Stability in the Presence of Peroxide Initiator Samples for UV-Vis measurements were prepared in a similar fashion as the preparation of reaction mixture stock solution in a 1 ml FTNIR quartz cuvette (1 cm 2 mm) as described above. Measurements were taken without any degassing. Formulations for the different UV-Vis measurements carried out are listed below based on the Figures in the paper and SI. SI, Figure S27A - [BTPA]:[RB]:[Asc acid] = 1 : 0.004: 0.1 with 5 mg BTPA, DMAc (0.432 ml), Milli-Q water (0.338 ml), RB (MW: g/mol 82 µl of mm of RB stock solution in water, ascorbic acid (MW: g/mol, 0.37 mg). The mixture was transferred to the quartz cuvette and irradiation was carried out for 20 minutes and the sample was left in the dark. UV-Vis measurements were taken at specified period of time. SI, Figure S27B - [BTPA]:[EY]:[Asc acid] = 1 : 0.004: 0.1 with 5 mg BTPA, DMAc (0.432 ml), Milli-Q water (0.365 ml), EY (MW: g/mol, 55 µl of mm of EY stock solution in water), ascorbic acid (MW: g/mol, 0.37 mg). The mixture was transferred to the quartz cuvette and irradiation was carried out for 20 minutes and the sample was left in the dark. UV-Vis measurements were taken at specified period of time. SI, Figure S30B - 8 mg PDMA (M n = g/mol), Milli-Q water (0.800 ml), RB (MW: g/mol 82 µl of mm of RB stock solution in water, ascorbic acid (MW: g/mol, 0.37 mg). The mixture was transferred to the quartz cuvette and irradiation was carried out for 10 minutes and the sample was left in the dark. UV-Vis measurements were taken at specified period of time. SI, Figure S30C - 8 mg PDMA (M n = g/mol), Milli-Q water (0.800 ml), EY (MW: g/mol, 55 µl of mm of EY stock solution in water), ascorbic acid (MW: g/mol, 0.37 mg). The mixture was transferred to the quartz cuvette and irradiation was carried out for 10 minutes and the sample was left in the dark. UV-Vis measurements were taken at specified period of time. S10

11 Semi-quantitative calculation of oxygen amount in the reaction vessel 1) ml ml of FTNIR cell: ml reaction solution and ml free air space 2) Amount of oxygen dissolved in ml reaction solution: I. Amount of oxygen dissolved in acrylic monomer is estimated to be between in the 0.6-2mM range. 3 II. Amount of oxygen dissolved in water is estimated to be between in the mm range. 4 3) Assuming we have maximum oxygen concentration in the reaction mixture (0.432 ml DMA and ml water) occupying 1 ml cuvette, the total amount of oxygen should be: (2 mm ml) + (0.47 mm ml) = 1.06 µmol 4) Assuming the diffusion of oxygen from the free headspace is negligible due to the formation of polymer film on the surface of the reaction mixture, the maximum amount of oxygen in the solution should : 1.06 µmol 5) In a typical polymerization with molar ratio of [RAFT]:[Asc acid] = 1 : 0.1 and 5 mg of BTPA is used: 0.4 mg of Asc acid (2.27 µmol) is needed 6) Assuming that 1 Ascorbic acid molecule reacts with 1 molecule of O 2 to generate 1 molecule of H 2 O 2, 5 with [DMA]:[BTPA]:[RB/EY]:[Asc acid] = 200 : 1 : : 0.1, the amount H 2 O 2 generated is : 1.06 µmol. Taking this into account the [DMA]:[BTPA]:[RB/EY]:[Asc acid]:[h 2 O 2 ] ratio should be 200 : 1 : : 0.1 : S11

12 Additional Figures: ppm w log M M = g/mol n M = g/mol n,theo M /M = 1.05 w n α FTNIR = 79 % Log M (g/mol) Figure S1. GPC profile of final polymer synthesized with 100 ppm RB in darkness after 45-min yellow light irradiation (λ max = 560 nm, intensity = 8 mw/cm 2 ) with BTPA as the chain transfer agent ([DMA]:[BTPA]:[Asc acid] = 200: 1 : 1, 4.9 M monomer concentration) without nitrogen sparging. S12

13 Figure S2. GPC profile of final polymer product synthesized in darkness after 20 min irradiation (A) and 45 min irradiation (B) for polymerization of DMA at room temperature under yellow light irradiation (λ max = 560 nm, intensity = 8 mw/cm 2 ) with BTPA as the chain transfer agent ([DMA]:[BTPA]:[RB]:[Asc acid] = 200: 1 : : 0.1, 20 ppm RB with respect to molar ratio of monomer and 4.9 M monomer concentration) without nitrogen sparging min irr Dark Conversion Time (min) Figure S3. Plot of conversion against time for polymerization of DMA by FTNIR measurements at room temperature under yellow light irradiation (λ max = 560 nm, intensity = 8 mw/cm 2 ) with BTPA as the chain transfer agent ([DMA]:[BTPA]:[RB]:[Asc acid] = 200: 1 : : 0.1, 20 ppm RB with respect to molar ratio of monomer and 4.9 M monomer concentration) without nitrogen sparging and with initial irradiation period of 20 minutes (green region) followed by commencement of polymerization in complete darkness (grey region). S13

14 Figure S MHz 1 H NMR spectrum in deuterated methanol (MeOD) for characterization of RAFT end group and molecular weight (M n,nmr = (I ppm /2)/(I ppm /1) MW M + MW RAFT = g/mol) of poly(n,n-dimethylacrylamide) synthesized in the presence of 20 ppm Rose Bengal with 5 min yellow light irradiation followed by darkness. S14

15 Figure S5. Investigating the effects of brief initial irradiation periods of 1 min and 30 sec with Rose Bengal for RAFT photopolymerization of DMA by FTNIR measurements at room temperature under yellow light irradiation (λ max = 560 nm, intensity = 8 mw/cm 2 ) with BTPA as the chain transfer agent ([DMA]:[BTPA]:[EY]:[Asc acid] = 200: 1 : : 0.1, 20 ppm RB with respect to molar ratio of monomer and 4.9 M monomer concentration) without nitrogen sparging. (A) Plot of conversion against time for polymerization of DMA with initial irradiation period of 1 min (green region) followed by commencement of polymerization in complete darkness (grey region); (B) Plot of Ln([M] 0 /[M] t ) against time for polymerization of DMA in complete darkness after irradiation period of 1 min; (C) GPC profile of final polymer product synthesized in darkness after 1 min irradiation; (D) Plot of conversion against time for polymerization of DMA with initial irradiation period of 30 sec min (green region) followed by commencement of polymerization in complete darkness (grey region); (E) Plot of Ln([M] 0 /[M] t ) against time for polymerization of DMA in complete darkness after irradiation period of 30 sec; and (F) GPC profile of final polymer product synthesized in darkness after 30 sec irradiation. Figure S6. Plot of conversion against time for polymerization of DMA in the presence of EY with initial irradiation period of 45 minutes (green region) followed by commencement of polymerization in complete darkness (grey region); and (B) GPC profile of final polymer product synthesized in darkness after 45 min irradiation. S15

16 Figure S7. Investigating the effects of brief initial irradiation periods of 1 min and 30 sec with Eosin Y for RAFT photopolymerization of DMA by FTNIR measurements at room temperature under green light irradiation (λ max = 530 nm, intensity = 4 mw/cm 2 ) with BTPA as the chain transfer agent ([DMA]:[BTPA]:[EY]:[Asc acid] = 200: 1 : : 0.1, 20 ppm RB with respect to molar ratio of monomer and 4.9 M monomer concentration) without nitrogen sparging. (A) Plot of conversion against time for polymerization of DMA with initial irradiation period of 1 min (green region) followed by commencement of polymerization in complete darkness (grey region); (B) Plot of Ln([M] 0 /[M] t ) against time for polymerization of DMA in complete darkness after irradiation period of 1 min; (C) GPC profile of final polymer product synthesized in darkness after 1 min irradiation; (D) Plot of conversion against time for polymerization of DMA with initial irradiation period of 30 sec min (green region) followed by commencement of polymerization in complete darkness (grey region); (E) Plot of Ln([M] 0 /[M] t ) against time for polymerization of DMA in complete darkness after irradiation period of 30 sec; and (F) GPC profile of final polymer product synthesized in darkness after 30 sec irradiation. S16

17 Figure S8. RAFT photopolymerization of DMA with Eosin Y (EY) mapped with three reaction mixtures polymerized at room temperature under 5 min green light irradiation (λ max = 530 nm, intensity = 4 mw/cm 2 ) with BTPA as the chain transfer agent ([DMA]:[BTPA]:[EY]:[Asc acid] = 200: 1 : : 0.1, 20 ppm EY with respect to molar ratio of monomer and 4.9 M monomer concentration) without nitrogen sparging and with each reaction stopped at specified time points. (A) Plot of molecular weight (M n ) against time for polymerization of DMA with each reaction stopped at different time points; and (B) GPC profiles for evolution of molecular weights of the polymers at different time points. Figure S9. RAFT photopolymerization of DMA with Rose Bengal (RB) mapped with three reaction mixtures polymerized at room temperature under 20 min green light irradiation (λ max = 560 nm, intensity = 8 mw/cm 2 ) with BTPA as the chain transfer agent ([DMA]:[BTPA]:[RB]:[Asc acid] = 200: 1 : : 0.1, 20 ppm RB with respect to molar ratio of monomer and 4.9 M monomer concentration) without nitrogen sparging and with each reaction stopped at specified time points. (A) Plot of molecular weight (M n ) against time for polymerization of DMA with each reaction stopped at different time points; and (B) GPC profiles for evolution of molecular weights of the polymers at different time points. S17

18 Figure S MHz 1 H NMR spectrum in deuterated methanol (MeOD) for characterization of RAFT end group and molecular weight (M n,nmr = (I 4.2 ppm /2)/(I 7.65 ppm /1) MW M + MW RAFT = g/mol) of poly(n,ndimethylacrylamide) synthesized in the presence of 20 ppm Rose Bengal with 45 min yellow light irradiation followed by darkness. Figure S MHz 1 H NMR spectrum of PDMA macro-cta in deuterated methanol (MeOD) for characterization of RAFT end group and molecular weight (M n,nmr = (I ppm /2)/(I ppm /1) MW M + S18

19 MW RAFT = g/mol) of the polymer synthesized in the presence of 20 ppm Eosin Y with 20 min green light irradiation followed by darkness. Figure S12. Mapping visual changes in Eosin Y (EY) (top) and changes in UV-Vis absorption profile (bottom) in a typical DMA polymerization mixture upon irradiation under green light (λ max = 530 nm, intensity = 4 mw/cm 2 ) for a specific period of time. Figure S13. GPC profile of final polymer products synthesized from continuous irradiation with Eosin Y (A), Rose Bengal (B) and 45 min irradiation with Eosin Y. S19

20 Figure S14. Investigating the effects of complete removal of air on RAFT photopolymerization of DMA with FTNIR measurements carried out at room temperature with 20-minute irradiation followed by complete darkness with BTPA as the chain transfer agent ([DMA]:[BTPA]:[EY or RB]:[Asc acid] = 200: 1 : : 0.1, 20 ppm EY or RB with respect to molar ratio of monomer and 4.9 M monomer concentration). (A) Plot of conversion against time for polymerization of DMA in the presence of EY under 20 min green light irradiation (λ max = 530 nm, intensity = 4 mw/cm 2 ) followed by darkness; and (B) Plot of conversion against time for polymerization of DMA in the presence of RB under 20 min yellow light irradiation (λ max = 560 nm, intensity = 8 mw/cm 2 ) followed by darkness. S20

21 Figure S15. Investigating the effects of addition of different volumes of air in reaction mixtures sparged with nitrogen on RAFT photopolymerization of DMA in the presence Eosin Y through FTNIR measurements at room temperature under 20-minute green light irradiation (λ max = 530 nm, intensity = 4 mw/cm 2 ) with BTPA as the chain transfer agent ([DMA]:[BTPA]:[EY]:[Asc acid] = 200: 1 : : 0.1, 20 ppm EY with respect to molar ratio of monomer and 4.9 M monomer concentration). (A) Plot of Ln([M 0 ]/[M] t ) against time for polymerization of DMA injected with 3 ml of air before irradiation; (B) Plot of Ln([M 0 ]/[M] t ) against time for polymerization of DMA injected with 5 ml of air before irradiation; (C) Plot of Ln([M 0 ]/[M] t ) against time for polymerization of DMA injected with 10 ml of air before irradiation; and (D) Plot of Ln([M 0 ]/[M] t ) against time for polymerization of DMA with no nitrogen sparging or addition of air. S21

22 Figure S16. UV-Vis measurement of singlet oxygen ( 1 O 2 ) quenching by 9,10- dimethylanthracene (DMeA) in the presence of Eosin Y (EY) upon green light irradiation (λ max = 530 nm, intensity = 4 mw/cm 2 ) at 1,5,10, and 20 minutes with the molar ratio of [EY]:[DMeA] = 1 : 0.8. (A) Complete absorption profile of EY and DMA at different time points of green light irradiation; (B) narrowed absorption profile of DMA at different time points of green light irradiation; and (C) narrowed absorption profile of EY at different time points of green light irradiation. Figure S17. UV-Vis measurement of singlet oxygen ( 1 O 2 ) quenching by 9,10- dimethylanthracene (DMeA) in the presence of Rose Bengal (RB) upon yellow light irradiation (λ max = 560 nm, intensity = 8 mw/cm 2 ) at 1,5,10,20 and 30 minutes with the molar ratio of [DMA]:[RB]:[DMeA]:[Asc acid] = 2000 : 0.08 : 0.2 : 1. (A) Complete absorption profile of RB and DMeA at different time points of yellow light irradiation; (B) narrowed S22

23 absorption profile of DMeA at different time points of green light irradiation; (C) narrowed absorption profile of RB at different time points of yellow light irradiation; and (D) plot of conversion against time for DMA polymerization at different time points of irradiation. Figure S18. UV-Vis measurement of singlet oxygen ( 1 O 2 ) quenching by 9,10- dimethylanthracene (DMeA) in the presence of Eosin Y (EY) upon yellow light irradiation (λ max = 530 nm, intensity = 4 mw/cm 2 ) at 1,5,10,20,30 and 40 minutes with the molar ratio of [DMA]:[EY]:[DMeA]:[Asc acid] = 2000 : 0.04 : 0.2 : 1. (A) Complete absorption profile of EY and DMeA at different time points of yellow light irradiation; (B) narrowed absorption profile of DMeA at different time points of green light irradiation; (C) narrowed absorption profile of EY at different time points of yellow light irradiation; and (D) plot of conversion against time for DMA polymerization at different time points of irradiation. S23

24 Figure S MHz 1 H NMR spectrum in deuterated DMSO for characterization of hydrogen peroxide from commercial source (top) with hydrogen peroxide generated from interaction between singlet oxygen and ascorbic acid (bottom) upon irradiation. Figure S MHz 1 H NMR spectrum in deuterated DMSO for characterization of hydrogen peroxide from commercial source (top) with hydrogen peroxide generated from interaction between singlet oxygen and sodium ascorbate (bottom) upon irradiation. S24

25 Figure S MHz 1 H NMR spectrum in deuterated DMSO for characterization of hydrogen peroxide from commercial source (top) with hydrogen peroxide generated from interaction between singlet oxygen and sodium ascorbate (bottom) upon irradiation. Figure S22. RAFT photopolymerization of DMA in the presence of Rose Bengal (RB) and sodium ascorbate (Na + Asc) measured by FTNIR measurements at room temperature under yellow light irradiation (λ max = 560 nm, intensity = 8 mw/cm 2 ) with BTPA as the chain transfer agent ([DMA]:[BTPA]:[RB]:[Na + Asc] = 200: 1 : : 0.1, 20 ppm RB with respect to molar ratio of monomer and 4.9 M monomer concentration) without nitrogen sparging. (A) Plot of conversion against time for polymerization of DMA with initial irradiation period of 5 minutes (green region) followed by commencement of polymerization in complete darkness (grey region); (B) Plot of Ln([M 0 ]/[M] t ) against time for polymerization of DMA in complete darkness after 5 min irradiation period; and (C) GPC profile of final polymer product synthesized in darkness after 5 min irradiation. S25

26 Figure S MHz 1 H NMR spectrum in deuterated methanol (MeOD) for characterization of RAFT end group and molecular weight (M n,nmr = (I ppm /2)/(I ppm /1) MW M + MW RAFT = g/mol) of poly(n,n-dimethylacrylamide) synthesized in the presence of 20 ppm Rose Bengal and sodium ascorbate with 5 min yellow light irradiation followed by darkness. Figure S24. RAFT photopolymerization of DMA in the presence of Eosin Y (EY) and sodium ascorbate (Na + Asc) measured by FTNIR measurements at room temperature under green light irradiation (λ max = 530 nm, intensity = 4 mw/cm 2 ) with BTPA as the chain transfer agent ([DMA]:[BTPA]:[EY]:[Na + Asc] = 200: 1 : : 0.1, 20 ppm EY with respect to molar ratio of monomer and 4.9 M monomer concentration) without nitrogen sparging. (A) Plot of conversion against time for polymerization of DMA with initial irradiation period of 5 minutes (green region) followed by commencement of polymerization in complete darkness (grey region); (B) Plot of Ln([M 0 ]/[M] t ) against time for polymerization of DMA in complete darkness after 5 min irradiation period; and (C) GPC profile of final polymer product synthesized in darkness after 5 min irradiation. S26

27 Figure S MHz 1 H NMR spectrum in deuterated methanol (MeOD) for characterization of RAFT end group and molecular weight (M n,nmr = (I ppm /2)/(I ppm /1) MW M + MW RAFT = g/mol) of poly(n,n-dimethylacrylamide) synthesized in the presence of 20 ppm Eosin Y and sodium ascorbate with 5 min yellow light irradiation followed by darkness. S27

28 Figure S26. Trapping of hydroxyl radical generated during oxidation of sodium ascorbate by hydrogen peroxide (H 2 O 2 ) using terephthalic acid to generate monohydroxyterephthalate. (A) Normalized fluorescence measurements of the reaction mixture before irradiation (0 hour) and after leaving in darkness for 6 hours; and (B) normalized fluorescence measurements of the reaction mixture after irradiation for 6 hours. Figure S27. Control study for DMA polymerization with FTNIR in the presence of Rose Bengal with 5-min yellow light irradiation (λ max = 560 nm, intensity = 8 mw/cm 2 ) with no BTPA as the chain transfer agent ([DMA]:[BTPA]:[RB]:[Asc acid] = 200: 0 : : 0.1, 20 ppm RB with respect to molar ratio of monomer and 4.9 M monomer concentration) without nitrogen sparging. (A) Plot of conversion against time upon irradiation for 5 minutes followed by polymerization in complete darkness; and (B) Plot of Ln([M 0 ]/[M] t ) against time for polymerization of DMA with RB upon irradiation for 5 minutes followed by polymerization in complete darkness. S28

29 Conversion (A) 20 min irr. - Eosin Y with no RAFT Ln[M]0/[Mt] (B) min irr. - Eosin Y with no RAFT Time (min) Time (min) Figure S28. Control study for DMA polymerization with FTNIR in the presence of Eosin Y with 20 min green light irradiation (λ max = 530 nm, intensity = 4 mw/cm 2 ) with no BTPA as the chain transfer agent ([DMA]:[BTPA]:[RB]:[Asc acid] = 200: 0 : : 0.1, 20 ppm RB with respect to molar ratio of monomer and 4.9 M monomer concentration) without nitrogen sparging. (A) Plot of conversion against time upon irradiation for 20 minutes followed by polymerization in complete darkness; and (B) Plot of Ln([M 0 ]/[M] t ) against time for polymerization of DMA with RB upon irradiation for 20 minutes followed by polymerization in complete darkness. Figure S29. UV-Vis absorption profiles to determine the extent of degradation of trithiocarbonate in the absence of monomer. (A) Absorption profile for a mixture consisting of BTPA, ascorbic acid, RB, water and DMAc before and after 20- min irradiation; and (B) absorption profile for a mixture consisting of BTPA,ascorbic acid, EY, water and DMAc before and after 20- min irradiation. S29

30 Figure S MHz 1 H NMR spectrum in deuterated dimethyl sulphoxide (DMSO-d6) for characterization of trithiocarbonate after 10 min irradiation (in the presence of Rose Bengal, ascorbic acid, water, and DMAc) followed by 5 hours in darkness. S30

31 Figure S MHz 1 H NMR spectrum in deuterated dimethyl sulphoxide (DMSO-d6) for characterization of trithiocarbonate after 10 min irradiation (in the presence of Eosin Y, ascorbic acid, water, and DMAc) followed by 4 hours in darkness. Figure S32. UV-Vis absorption profiles of PDMA macro-cta before and after irradiation to determine the degradation of trithiocarbonate end group. (A) Absorption profile of PDMA macro-cta (0.953 mm) in water in the absence of any irradiation or photocatalysts; (B) Absorption profile of PDMA macro-cta in water in the presence of RB before and after irradiation in the presence of ascorbic acid; and (C) Absorption profile of PDMA macro-cta in water in the presence of EY before and after irradiation in the presence of ascorbic acid. S31

32 Figure S33. Mapping visual changes in methylene blue (MB) (top) and changes in UV-Vis absorption profile (bottom) in a typical DMA polymerization mixture upon irradiation under red light (λ max = 650 nm, intensity = 9 mw/cm 2 ) for 5 minutes. Figure S34. DMA polymerization measured with FTNIR in the presence of Fluorescein (FL) with 45-min yellow light irradiation (λ max = 505 nm, intensity = 4 mw/cm 2 ) with BTPA as the chain transfer agent ([DMA]:[BTPA]:[RB]:[Asc acid] = 200: 1 : : 0.1, 60 ppm FL with respect to molar ratio of monomer and S32

33 4.9 M monomer concentration) without nitrogen sparging. (A) Plot of conversion against time upon irradiation for 45 minutes followed by polymerization in complete darkness; and (B) Plot of Ln([M 0 ]/[M] t ) against time for polymerization of DMA with FL upon irradiation for 45 minutes followed by polymerization in complete darkness. Table S1. Control in complete darkness for 24 hours using Eosin Y (4.9 M monomer concentration and 20 ppm photocatalyst) with BTPA as the chain transfer agent. a no. Exp. Cond. a Time [DMA]:[BTPA]:[EY]:[Asc] (h) α b (%) 1 200: 1 : : : 0 : : : 0 : : : 0 : 0 : Note: a Reactions were performed with no nitrogen sparging at room temperature in water. b Monomer conversion was determined by using 1 H NMR spectroscopy. Table S2. Control in complete darkness for 24 hours using Rose Bengal (4.9 M monomer concentration and 20 ppm photocatalyst) with BTPA as the chain transfer agent. a no. Exp. Cond. a Time [DMA]:[BTPA]:[RB]:[Asc (h) acid] α b (%) 1 200: 1 : : : 0 : : : 0 : : d 4 c 200: 1 : : d Note: a Reactions were performed with no nitrogen sparging at room temperature in water. b Monomer conversion was determined by using 1 H NMR spectroscopy. c Degassed for 50 minutes. d Slight increase in monomer conversion could be due monomer self-activation. S33

34 Additional References 1. Shanmugam, S.; Xu, J.; Boyer, C., Utilizing the electron transfer mechanism of chlorophyll a under light for controlled radical polymerization. Chemical Science 2015, 6 (2), Corrigan, N.; Rosli, D.; Jones, J. W. J.; Xu, J.; Boyer, C., Oxygen Tolerance in Living Radical Polymerization: Investigation of Mechanism and Implementation in Continuous Flow Polymerization. Macromolecules 2016, 49 (18), Gou, L.; Coretsopoulos, C. N.; Scranton, A. B., Measurement of the dissolved oxygen concentration in acrylate monomers with a novel photochemical method. J. Polym. Sci., Part A: Polym. Chem. 2004, 42 (5), Chen, Y.-P.; Liu, S.-Y.; Yu, H.-Q., A simple and rapid method for measuring dissolved oxygen in waters with gold microelectrode. Analytica Chimica Acta 2007, 598 (2), Kramarenko, G. G.; Hummel, S. G.; Martin, S. M.; Buettner, G. R., Ascorbate Reacts with Singlet Oxygen to Produce Hydrogen Peroxide. Photochem. Photobiol. 2006, 82 (6), S34