Supporting Information. Systematic Alkaline Stability Study of Polymer Backbones for Anion Exchange Membrane Applications

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1 Supporting Information Systematic Alkaline Stability Study of Polymer Backbones for Anion Exchange Membrane Applications Angela D. Mohanty, a Steven E. Tignor, a Jessica A. Krause, a Yoong-Kee Choe, b, * and Chulsung Bae a, * a Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute, Troy, NY 12180, USA b National Institute of Advanced Industrial Science & Technology, Tsukuba, , Japan Table of Contents: 1. General experimental details... S3 2. Synthesis of polymer materials... S3 Scheme S1: Fluorination reaction of PSU-CH 2 Cl to form PSU-CH 2 F... S4 Scheme S2: Radical bromination of PPO to form PPO-CH 2 Br... S5 Scheme S3: Amination of PPO-CH 2 Br to form PPO-CH 2 QA... S5 Scheme S4: Synthesis of PPO-(CH 2 ) 6 QA... S6 Scheme S5: Acid-catalyzed Friedel-Crafts polycondensation... S6 Scheme S6: Chloromethylation of SEBS to form SEBS-CH 2 Cl... S7 3. General procedure for KOH alkaline stability test (i.e. condition i)... S7 4. General procedure for NaOCH 3 alkaline stability test (i.e. condition ii)... S7 5. General procedure for 2M NaOCH 3 polymer film alkaline stability test (i.e. condition iii)... S8 6. Synthesis of small molecule model compounds... S8 Scheme S7: Coupling reactions to prepare compounds 1, 2, and 3... S8 Scheme S8: Radical bromination reactions to prepare compounds 4 and 5... S9 Scheme S9: Amination reactions to prepare compounds 6 and 7... S9 Scheme S10: Methylation reactions to prepare compounds 8 and 9... S10 Scheme S11: Copper acetate coupling reactions to prepare compounds 10 and S10 Scheme S12: Bromination of 11 to prepare compound S11 Scheme S13: Amination of 12 to prepare compound S11 Scheme S14: Methylation of 13 to prepare compound S11 Scheme S15: Friedel-Crafts acylation of diphenyl ether... S11 Scheme S16: Reduction of ketone 15 to compound S12 Scheme S17: Amination of compound 16 with dimethylamine... S12 Scheme S18: Methylation of 17 to prepare quaternary ammonium S12 7. General procedure for room temperature small molecule stability test... S13 8. General procedure for 80 and 100 C small molecule stability tests... S13 9. General procedure for PPO NaOCH 3 alkaline stability test (i.e. condition iv)... S GPC and NMR data for polymer alkaline stability studies... S14 Alkyl-tethered polysulfones (Table S1, Figures S1, S2, & S3)... S14 PSU (Table S2, Figures S4 & S5)... S16 PSU-CH 2 Cl (Table S3, Figures S6 & S7)... S17 PSU-CH 2 F (Table S4, Figures S8 & S9)... S18 PPO (Table S5, Figures S10 & S11)... S19 PPO-CH 2 Br (Table S6, Figures S12 & S13)... S20 PB (Table S7, Figures S14 & S15)... S21 PBA (Table S8, Figures S16 & S17)... S22 SEBS (Table S9, Figures S18 & S19)... S23 S1

2 SEBS-CH 2 Cl (Table S10, Figures S20 & S21)... S24 PPO-(CH 2 ) 6 Br (Table S11, Figures S76 & S77)... S52 PPO-CH 2 QA and PPO-(CH 2 ) 6 QA (Table S12, Figure S78)... S NMR spectra for small molecule stability studies... S Computational simulation details and data... S References... S57 S2

3 1. General experimental details Unless otherwise noted, all reagents were purchased from Alfa Aesar, Acros Organics, or Sigma Aldrich and were used without further purification. Solvents (chloroform, tetrachloroethane, dichloromethane, methanol, ethanol, tetrahydrofuran (THF), dioxane, dimethylsulfoxide (DMSO), and N,Ndimethylacetamide) were reagent grade and used as received. Anhydrous THF and DMSO were obtained from Acros Organics and stored in a nitrogen-filled glovebox. Deuterated solvents (CDCl 3, DMSO-d 6 ) were purchased from Cambridge Isotope Laboratories, Inc. Bis(pinacolato)diboron (B 2 Pin 2 ) and chloro(1,5-cyclooctadiene)iridium(i) dimer ([IrCl(COD)] 2 ) were donated by Frontier Scientific Co. and Sinocompound Technology Co., respectively. Udel polysulfone (PSU) was purchased from Scientific Polymer Products, Inc. Poly(phenylene oxide) (PPO) and Polystyrene-b-poly(ethylene-co-butylene)-bpolystyrene (SEBS) [containing 30 mol% styrene content] were purchased from Sigma Aldrich. 1 H NMR spectra were obtained with a Varian Unity 500 MHz spectrometer. All NMR spectra were recorded at 25 C and chemical shifts were referenced to TMS internal standard (at 0.00 ppm). NMR spectra were processed with MestReNova 8.1 (Mestrelab Research SL) software. Molecular weight measurement was performed using a Viscotek GPC equipped with three general mixed-bed Viscotek columns and a RI detector at 30 C with a flow rate of 0.8 ml/min using THF as the mobile phase. The instrument was calibrated using polystyrene standards. 2. Synthesis of polymer materials Synthesis of PSU-CH 2 Cl: Chloromethylation of PSU was performed according to a previous literature report. 1 In a two-neck 250 ml round-bottom flask, PSU (5.00 g, 11.3 mmol polymer repeat unit) was dissolved in tetrachloroethane (150 ml) under a nitrogen atmosphere. Chloromethyl methyl ether (CMME, 17.2 ml, 226 mmol) and zinc chloride (0.77 g, 5.7 mmol) were added. After stirring at 50 C for 2.5 h, the reaction was cooled to rt and poured into methanol to precipitate the polymer. The crude product was dissolved in chloroform and then poured into methanol to precipitate the polymer. PSU- CH 2 Cl was isolated as white fibers after drying under vacuum at rt for 14 h (4.20 g, 81 mol% CH 2 Cl). The mol% of CH 2 Cl was estimated based on the relative intensity of resonances of C(CH 3 ) 2 in the polymer main chain (at ppm) and the methylene of the chloromethyl group (at ppm). NMR spectrum is shown in Figure S2b, and GPC data are shown in Table S1 and Figure S1. Hydroxylation of PSU-CH 2 Cl to PSU-CH 2 OH: To a 250 ml round-bottom flask was added KOH (0.41 g, 7.3 mmol), 18-crown-6 (1.90 g, 7.30 mmol), THF (16 ml), and water (1.2 ml). After stirring at rt for 30 min, a solution of PSU-CH 2 Cl (1.50 g, 81 mol% CH 2 Cl, 2.43 mmol of CH 2 Cl) in THF (34 ml) was added to the reaction mixture. The reaction was stirred at 60 C for 2 h, then at rt for 12 h. The reaction was stopped by precipitating the polymer in 1M HCl aqueous solution. The polymer was collected by filtration, dissolved in DMSO, and precipitated in 1M HCl. PSU-CH 2 OH was isolated as an off-white colored solid after drying under vacuum at rt for 14 h (1.20 g, quantitative conversion to CH 2 OH). NMR spectrum is shown in Figure S2c, and GPC data are shown Table S1 and Figure S1. Synthesis of PSU-CH 2 O-Br: In a nitrogen-filled glovebox, PSU-CH 2 OH (0.76 g, 81 mol% CH 2 OH, 1.30 mmol of CH 2 OH) was dissolved in a 1:1 mixture of anhydrous THF (11.6 ml) and anhydrous DMSO (11.6 ml) in a 40 ml vial. After dissolution, 1,6-dibromohexane (1.6 ml, 10.4 mmol) followed by NaH (60 wt% oil dispersion, 0.16 g, 3.9 mmol) were added under nitrogen atmosphere. After stirring at rt for 14 h, the reaction was poured into methanol to precipitate the polymer. The polymer was filtered, dissolved in THF, and filtered through a short plug of silica gel to remove insoluble components. The filtrate was concentrated using a rotary evaporator and poured into methanol to precipitate the polymer. PSU-CH 2 O-Br was isolated as a yellow powder after drying under vacuum at rt for 14 h (0.50 g, quantitative conversion). NMR spectrum is shown in Figure S2d, and GPC data are shown in Table S1 and Figure S1. S3

4 Synthesis of PSU-Bpin: Ir-catalyzed C H borylation of PSU was performed according to a previous literature procedure. 1 In a nitrogen-filled glovebox, PSU (5.00 g, 11.3 mmol polymer repeat unit), B 2 Pin 2 (1.70 g, 6.80 mmol), [IrCl(COD)] 2 (69 mg, 0.10 mmol), dtbpy (54 mg, 0.20 mmol), and anhydrous THF (25 ml) were placed into a 100 ml round-bottom flask. The flask was removed from the glovebox, fitted with a reflux condenser under nitrogen, and then stirred in an 75 C oil bath for 14 h. After cooling to rt, the reaction solution was diluted with THF (25 ml) and filtered through a short plug of silica gel to remove the catalyst. The filtrate was concentrated using a rotary evaporator and poured into methanol to precipitate the polymer. The dissolution and precipitation process was repeated one more time. PSU- Bpin was isolated as white fibers after drying under vacuum at rt for 14 h (6.10 g, 75 mol% Bpin). The mol% of Bpin was estimated based on the relative intensity of resonances of C(CH 3 ) 2 in the polymer main chain (at ppm) and the four methyl groups of Bpin (at ppm). NMR spectrum is shown in Figure 3b, and GPC data are shown in Table S1 and Figure S1. Oxidation of PSU-Bpin to PSU-OH: Oxidation of PSU-Bpin was performed according to a modified literature report. 2 PSU-Bpin (2.00 g, 75 mol% Bpin, 2.80 mmol of Bpin) was dissolved in dioxane (240 ml). 2M NaOH aqueous solution (12 ml) and 30% H 2 O 2 (12 ml) were slowly added in sequence to the stirring polymer solution. After stirring at 50 C for 1 h, the reaction was concentrated on a rotary evaporator to remove dioxane. The polymer was precipitated in water, filtered, and dissolved in DMSO. The polymer in DMSO solution was poured into 0.5M HCl aqueous solution to precipitate the polymer. PSU-OH was isolated as a yellow solid after drying under vacuum at rt for 14 h (1.90 g, quantitative conversion). NMR spectrum is shown in Figure S3c. The molecular weights of PSU-OH could not be analyzed with GPC due to its insolubility in THF. Synthesis of PSU-O-Br: In a nitrogen-filled glovebox, PSU-OH (1.90 g, 75 mol% OH, 3.20 mmol of OH) was dissolved in anhydrous DMSO (55 ml) in a 250 ml round-bottom flask. After dissolution, 1,6- dibromohexane (3.9 ml, 25.4 mmol) followed by NaH (60 wt% oil dispersion, 0.38 g, 9.5 mmol) were added under nitrogen atmosphere. After stirring at rt for 14 h, the reaction mixture was poured into methanol to precipitate the polymer. The polymer was filtered, dissolved in THF, and filtered through a short plug of silica gel to remove insoluble components. The filtrate was concentrated using a rotary evaporator and poured into methanol to precipitate the polymer. PSU-O-Br was isolated as a yellow powder after drying under vacuum at rt for 14 h (1.10 g, quantitative conversion). NMR spectrum is shown in Figure S3d, and GPC data are shown in Table S1 and Figure S1. General procedure for amination to form PSU-CH 2 O-QA and PSU-O-QA: The following is a general procedure for homogeneous amination to yield PSU-CH 2 O-QA and PSU-O-QA in Br - form. The respective precursor polymer [PSU-CH 2 O-Br (81% alkyl bromide) or PSU-O-Br (75% alkyl bromide)] was dissolved in N,N-dimethylacetamide (8% w/v) in a 40 ml vial. Aqueous trimethylamine (45 wt% in H 2 O, 5 equiv. based on mmol alkyl bromide) was added and the reaction was stirred at rt for 24 h. The reaction mixture was then filtered through cotton and cast onto a glass plate to form a film. The film was dried in an oven at 50 C for 12 h with a positive flow of air, followed by at 80 C for 4 h. The film was removed from the glass plate by immersion in water. Unfortunately, the films from both polymer systems were brittle and broke easily into small pieces (see Figure 1b). NMR specra of PSU-CH 2 O-QA and PSU- O-QA are shown in Figure S2e and Figure S3e, respectively. Scheme S1: Fluorination reaction of PSU-CH 2 Cl to form PSU-CH 2 F. S4

5 Synthesis of PSU-CH 2 F: Fluorination was performed according to a modified literature procedure. 3 Tetrabutylammonium fluoride trihydrate (TBAF-3H 2 O, 3.90 g, 15.0 mmol) was heated in a 40 ml vial with magnetic stirring at C under vacuum. After several hours, the sample became liquefied. After 24 h, a solution of PSU-CH 2 Cl (0.50 g, 130 mol% CH 2 Cl, 1.0 mmol of CH 2 Cl) in anhydrous THF (16 ml) was added to the anhydrous TBAF. The solution was stirred at 65 C for 3 h and at rt for 14 h, after which it was poured into methanol to precipitate the polymer. The polymer was filtered, dissolved in THF, and precipitated in methanol. PSU-CH 2 F was isolated as a white powder after drying under vacuum at rt for 14 h (0.30 g, 100% conversion to CH 2 Cl). NMR spectrum is shown in Figure S9, and GPC data are shown in Table S4 and Figure S8. 1 H NMR: 5.34 ppm (doublet for CH 2 F, J H-F = 47.6 Hz); 19 F NMR: 212 ppm (two triplets for CH 2 F both with J H-F = 46.4 Hz). Note: two triplets were observed in the 19 F NMR spectrum possibly due to uneven distribution of CH 2 F on the PSU aromatic rings. Scheme S2: Radical bromination of PPO to form PPO-CH 2 Br. Synthesis of PPO-CH 2 Br: Radical bromination of PPO was performed according to reported literature procedure. 4 To a 25 ml round-bottom flask was added PPO (1.00 g, 8.30 mmol polymer repeat unit), N- bromosuccinimide (NBS, 0.89 g, 5.0 mmol), 2,2 -azobis(2-methylpropionitrile) (AIBN, 41 mg, 0.25 mmol), and chlorobenzene (5 ml). The flask was fitted with a reflux condenser and the reaction was heated to reflux (~135 C) for 3 h. The reaction was then cooled to rt and poured into ethanol to precipitate the polymer as a dark brown sticky solid. The polymer was stirred in ethanol for 2 h, filtered, dissolved in chloroform, and precipitated again into ethanol. PPO-CH 2 Br was isolated as brown fibers after drying under vacuum at rt for 14 h (1.50 g, 39 mol% CH 2 Br). The mol% of CH 2 Br was estimated based on the relative intensity of the aromatic C H resonance in the polymer main chain (at ppm) the methylene resonance of the bromomethyl group (at ppm). NMR spectrum is shown in Figure S13, and GPC data are shown in Table S6 and Figure S12. Scheme S3: Amination of PPO-CH 2 Br to form PPO-CH 2 QA. Synthesis of PPO-CH 2 QA: Amination was performed according to a reported literature procedure. 5 PPO- CH 2 Br (0.50 g, 3.32 mmol CH 2 Br) was dissolved in N,N-dimethylacetamide (5 ml) in a 20 ml vial. A 45 wt% aqueous solution of trimethylamine (2.5 ml) was added and the reaction was stirred at rt for 24 h. The solution was then poured into a petri dish and the solvent was evaporated under a stream of air in a 70 C oven. The polymer was removed from the petri dish by soaking in water, and was then vacuum dried to yield PPO-CH 2 QA having 39 mol% CH 2 N(CH 3 ) 3 functional groups. S5

6 Scheme S4: Synthesis of PPO-(CH 2 ) 6 QA. Synthesis of PPO-CO(CH 2 ) 5 Br: Friedel-Crafts acylation of PPO was performed according to a reported literature procedure. 6 PPO (0.50 g, 4.17 mmol) was dissolved in chlorobenzene (20 ml) in a 40 ml vial fitted with a Teflon-lined cap. The solution was cooled in an ice bath, and 6-bromohexanoyl chloride (0.96 ml, 6.25 mmol) and AlCl 3 (0.260 g, 1.94 mmol) were added. The ice bath was removed and the reaction was stirred at rt for 14 h. After 14 h, the reaction was poured into methanol to precipitate the polymer. The polymer was filtered, redissolved in chloroform, and precipitated again into methanol. PPO-CO(CH 2 ) 5 Br was isolated as white fibers after drying under vacuum at rt for 8 h (0.72 g, 24 mol% CO(CH 2 ) 5 Br). Synthesis of PPO-(CH 2 ) 6 Br: Reduction of the ketone was performed according to literature procedure. 6 To a 100 ml round-bottom flask equipped with a reflux condenser was added PPO-CO(CH 2 ) 5 Br (0.50 g, 0.73 mmol CO(CH 2 ) 5 Br), triethylsilane (0.77 ml, 4.8 mmol), trifluoroacetic acid (29 ml), and dichloroethane (20 ml). After heating at 70 C for 17 h, the solution was poured slowly into a 30 wt% KOH aqueous solution (50 ml). After stirring for 30 min, the resulting biphasic mixture was poured into a separatory funnel and the aqueous layer was removed. The organic layer was washed with water (2 x 10 ml) and then poured into a beaker containing water (50 ml). The solution in beaker was stirred and heated to 50 C to evaporate volatile organic solvents. The clumpy polymer precipitates were filtered and redissolved in chloroform, and poured into ethanol to precipitate polymer. After vacuum drying at rt for 8 h, PPO-(CH 2 ) 6 Br was isolated as white fibers (0.22 g, 100% reduction of ketone, 24 mol% (CH 2 ) 6 Br). Synthesis of PPO-(CH 2 ) 6 QA: Amination was performed according to literature procedure. 6 To a 20 ml vial was added PPO-(CH 2 ) 6 Br (0.20 g, 0.30 mmol (CH 2 ) 6 Br), N-methyl-2-pyrrolidone (3.6 ml), and a 45 wt% aqueous solution of trimethylamine (0.16 ml, 1.2 mmol). After stirring at 35 C for 24 h, the solution was poured into a petri dish and the solvent was evaporated under a stream of air in a 80 C oven. The polymer was removed from the petri dish by soaking in water, and then was vacuum dried to yield PPO-(CH 2 ) 6 QA having 24 mol% (CH 2 ) 6 N(CH 3 ) 3 functional groups. Scheme S5: Acid-catalyzed polycondensation of biphenyl and trifluoromethyl ketones. Synthesis of PB: Acid-catalyzed polycondensation of biphenyl was performed according to a reported literature procedure. 7 To a 40 ml vial was added biphenyl (1.00 g, 6.50 mmol), which was vacuum dried and purged with nitrogen. Anhydrous dichloromethane (4.8 ml) and 1,1,1-trifluoroacetone (0.7 ml, 7.8 mmol) were added via a syringe. The reaction mixture was cooled in an ice bath and trifluoromethanesulfonic acid (TFSA, 4.8 ml) was added in one portion. The reaction mixture was stirred in ice bath for 30 min, then at rt for 3.5 h. The resulting dark-brown, gel-like solid was shredded and poured slowly into methanol. The precipitated polymer was stirred in warm methanol (~45 C) for 2 h, filtered, dissolved in tetrachloroethane, and precipitated in methanol. PB was isolated as white fibers S6

7 after drying under vacuum at rt for 14 h (1.96 g). NMR spectrum is shown in Figure S15, and GPC data are shown in Table S7 and Figure S14. Synthesis of PBA: PBA was polymerized according to a similar procedure of PB. A mixture of 7-bromo- 1,1,1-trifluoroheptan-2-one (1.12 g, 4.53 mmol), biphenyl (0.70 g, 4.53 mmol), anhydrous dichloromethane (3.0 ml) and TFSA (3.0 ml) was stirred at room temperature for 12 h and then poured into methanol. The polymer was filtered and washed with hot methanol. PBA was isolated as white fibers after drying under vacuum at rt for 14 h (1.70 g). NMR spectrum is shown in Figure S17, and GPC data are shown in Table S8 and Figure S16. Scheme S6: Chloromethylation of SEBS to form SEBS-CH 2 Cl. Synthesis of SEBS-CH 2 Cl: In a two-neck 100 ml round bottom flask, SEBS (0.50 g, 2.07 mmol aromatic styrene units) was dissolved in tetrachloroethane (15 ml) under a nitrogen atmosphere. Chloromethyl methyl ether (CMME, 1.70 ml, 20.7 mmol) and zinc chloride (0.17 g, 1.2 mmol) were added. After stirring at 50 C for 45 min, the reaction mixture was cooled to rt and poured into methanol to precipitate the polymer. The crude product was dissolved in chloroform and then poured into methanol to precipitate the polymer. SEBS-CH 2 Cl was isolated as white fibers after drying under vacuum at rt for 14 h (0.53 g, 6.8 mol% CH 2 Cl). The mol% of CH 2 Cl was estimated based on the relative intensity of CH 3 in the polymer main chain of 1,2-butylene units (at ppm) and the methylene of the chloromethyl group (at ppm). NMR spectrum is shown in Figure S21, and GPC data are shown in Table S10 and Figure S General procedure for KOH alkaline stability test (i.e. condition i) The treatment of polymers with KOH was followed according to the same procedure as the synthesis of PSU-CH 2 OH. To a 20 ml vial was added KOH (3 equiv. based on mmol polymer repeat unit), 18- crown-6 (3 equiv. based on mmol KOH), THF (2 ml), and water (0.5 ml). After stirring at rt for 30 min, a solution of the desired polymer (0.1 g) in THF (2 ml) was added to the reaction mixture. The reaction was stirred at 60 C for 2 h, then at rt for 12 h. The reaction was stopped by precipitating the polymer in 0.5M HCl aqueous solution. The alkaline treated polymer was collected by filtration, washed with water, and dried under vacuum at rt for 14 h. The polymers were then analyzed with GPC and 1 H NMR spectroscopy. 4. General procedure for NaOCH 3 alkaline stability test (i.e. condition ii) The desired polymer (0.1 g) was dissolved in THF (4 ml) in a 20 ml vial. A NaOCH 3 solution in methanol (30% w/w, 10 equiv. based on mmol polymer repeat unit) was added and the reaction was stirred at 60 C for 14 h. The alkaline treated polymer was collected by filtration, washed with water, and dried under vacuum at rt for 14 h. The polymers were then analyzed with GPC and 1 H NMR spectroscopy. S7

8 5. General procedure for 2M NaOCH 3 polymer film alkaline stability test (i.e. condition iii) Thin films (approximately m thick) of each polymer material were prepared by solution casting (solvent: chloroform or THF) onto a glass plate. An approximately 2 x 2 cm 2 piece of each film was immersed in a 2M NaOCH 3 /methanol solution. The solution was heated to 60 C for 7 days, after which the films were removed and rinsed with water for 12 h. The films were dried under vacuum at rt for 14 h. The polymer films were then analyzed with GPC and 1 H NMR spectroscopy. 6. Synthesis of small molecule model compounds Scheme S7: Coupling reactions to prepare compounds 1, 2, and 3. Synthesis of 4-phenoxydiphenyl sulfone [1]: To a 50 ml round-bottom flask was added 4-chlorophenyl phenyl sulfone (2.00 g, 7.91 mmol), phenol (1.86 g, 19.8 mmol), potassium carbonate (3.28 g, 23.8 mmol), N,N-dimethylacetamide (20 ml), and a magnetic stirring bar, and the solution was heated to 160 o C for 24 h. After the reaction was complete, the solution was extracted with dichloromethane (100 ml) and washed with water (2 x 25 ml). The combined organic layer was dried over MgSO 4, filtered, and concentrated using a rotary evaporator. The crude product was then recrystallized from ether to yield pure product 1 as white crystals (0.30 g, 12% yield). HRMS for MH + : expected , observed Synthesis of 1-(2-methylphenoxy)-4-(phenylsulfonyl)benzene [2]: To a 100 ml round-bottom flask was added 4-chlorophenyl phenyl sulfone (4.00 g, 15.8 mmol), o-cresol (5.00 ml, 47.5 mmol), potassium carbonate (8.75 g, 63.3 mmol), N,N-dimethylacetamide (40 ml), and a magnetic stirring bar, and the solution was heated to 160 o C for 24 h. After the reaction was complete, the solution was extracted with dichloromethane (2x100 ml) and washed with water (3x50 ml). The combined organic layer was dried over MgSO 4, filtered, and concentrated using a rotary evaporator. The crude product was then recrystallized from ether to yield pure product 2 as brown crystals (4.34 g, 84% yield). HRMS for MH + : expected , observed Synthesis of 1-(3-methylphenoxy)-4-(phenylsulfonyl)benzene [3]: To a 100 ml round-bottom flask was added 4-chlorophenyl phenyl sulfone (2.00 g, 7.91 mmol), m-cresol (2.5 ml, 23.7 mmol), potassium carbonate (4.375 g, 31.7 mmol), N,N-dimethylacetamide (20 ml), and a magnetic stirring bar, and the solution was heated to 160 o C for 24 h. After the reaction was complete, the solution was extracted with dichloromethane (2 x 100 ml) and washed with 1M HCl (50 ml), distilled water (100 ml), and brine (50 ml). The combined organic layter was dried over MgSO 4, filtered, and concentrated using a rotary S8

9 evaporator. The crude product was recrystallized from ether to yield pure product 3 as a brown solid (1.30 g, 51% yield). HRMS for MH + : expected , observed Scheme S8: Radical bromination to prepare compounds 4 and 5. Synthesis of 1-(2-bromomethylphenoxy)-4-(phenylsulfonyl)benzene [4]: To a 50 ml round-bottom flask attached with a reflux condenser was added compound 2 (0.500 g, 1.54 mmol), N-bromosuccinimide (0.274 g, 1.54 mmol), 2,2 -azobis(2-methylpropionitrile) (AIBN) (10 mg, mmol), carbon tetrachloride (15 ml), and a magnetic stirring bar, and the solution was stirred at 80 o C for 2 h. The reaction was cooled and filtered to remove succinimide, then concentrated using a rotary evaporator. The resulting crude product 4 was used in the next step without further purification. Synthesis of 1-(3-bromomethylphenoxy)-4-(phenylsulfonyl)benzene [5]: Crude product 5 was obtained using a similar procedure for preparation of compound 4 with compound 3 (1.00 g, 3.10 mmol), N- bromosuccinimide (0.550 g, 3.10 mmol), AIBN (20 mg, 0.12 mmol), and carbon tetrachloride (20 ml). The resulting crude product 5 was used in the next step without further purification. Scheme S9: Amination reactions to prepare compounds 6 and 7. Synthesis of 1-(2-(N,N-dimethylamino)phenoxy)-4-(phenylsulfonyl)benzene [6]: To a 25 ml roundbottom flask was added crude compound 4, a 2M solution of dimethylamine in THF (2.5 ml), THF (5 ml), and a magnetic stirring bar. After stirring the solution at room temperature for 24 hours, 1M sodium bicarbonate (25 ml) was added. The solution was extracted with diethyl ether (25 ml) and washed with water (2 x 25 ml), and the combined organic layer was dried over MgSO 4, filtered, and concentrated using a rotary evaporator. The resulting crude product 6 was used in the next step without further purification. Synthesis of 1-(3-(N,N-dimethylamino)phenoxy)-4-(phenylsulfonyl)benzene [7]: Crude product 7 was obtained using a similar procedure for preparation of compound 6 with crude compound 5, a 2M solution of dimethylamine in THF (5 ml), and dry THF (5 ml) and used in the next step without further purificaiton. S9

10 Scheme S10: Methylation reactions to prepare compounds 8 and 9. Synthesis of ortho-substituted quaternary ammonium [8]: To a 25 ml round-bottom flask was added crude compound 6, diethyl ether (about 10 ml; until completely dissolved), and a magnetic stirring bar. After addition of methyl iodide (0.4 ml, 3.1 mmol) at room temperature, a solid began to form in a few minutes. The solution was stirred for 2 h and filtered to yield compound 8 as a white solid (0.32 g). Synthesis of meta-substituted quaternary ammonium [9]: A similar procedure for preparation of compound 8 using crude compound 7 and methyl iodide (0.8 ml, 6.2 mmo) yielded compound 9 as a white solid (0.18 g). Scheme S11: Copper acetate coupling reactions to prepare compounds 10 and 11. Synthesis of 4-tert-butyl-1-phenoxybenzene [10]: The coupling reaction was performed according to a reported literature procedure. 8 To a 100 ml round-bottom flask was added 4-tert-butylphenol (1.00 g, 6.67 mmol), phenylboronic acid (1.64 g, 13.3 mmol), copper(ii) acetate (1.21 g, 6.67 mmol), pyridine (2.69 ml, 33.3 mmol), 4Å molecular sieves, and dichloromethane (30 ml), and the solution was stirred at room temperature. The progress of the reaction was monitored by GC-MS. When the reaction was complete (about 20 h), the solution was filtered and concentrated using a rotary evaporator. Purification of the crude product by flash column chromatography (400 ml of hexanes followed by 400 ml of a 2:1 mixture of dichloromethane/hexanes) afforded pure product 10 as a colorless oil (0.880 g, 59% yield). Synthesis of 4-tert-butyl-2-methyl-1-phenoxybenzene [11]: A similar procedure for preparation of compound 10 with 4-tert-butyl-2-methylphenol (0.200 g, 1.22 mmol), phenylboronic acid (0.300 g, 2.44 mmol), copper(ii) acetate (0.220 g, 1.22 mmol), pyridine (0.5 ml, 6.1 mmol), 4Å molecular sieves, and dichloromethane (20 ml) afforded pure product 11 as a colorless oil (0.210 g, 74% yield). S10

11 Scheme S12: Bromination of 11 to prepare compound 12. Synthesis of 4-tert-butyl-2-(bromomethyl)-1-phenoxybenzene [12]: Crude product 12 was obtained using a similar procedure for preparation of compound 4 with compound 11 (0.205 g, 0.9 mmol), N- bromosuccinimide (0.16 g, 0.9 mmol), AIBN (6 mg, mmol), and carbon tetrachloride (15 ml). The resulting crude product 12 was used in the next step without further purification. Scheme S13: Amination of 12 to prepare compound 13 Synthesis of 4-tert-butyl-(2-(N,N-dimethylamino)methyl)-1-phenoxybenzene [13]: Crude product 13 was obtained using a similar procedure for preparation of compound 6 with crude compound 12, a 2M solution of dimethylamine in THF (1 ml), and dry THF (5 ml) and used in the next step without further purificaiton. Scheme S14: Methylation of 13 to prepare compound 14 Synthesis of ortho-substituted quaternary ammonium [14]: A similar procedure for preparation of compound 8 with crude compound 13, diethyl ether (10 ml), and methyl iodide (0.5 ml, 3.9 mmol) yielded compound 14 as a white solid (0.18 g). Scheme S15: Friedel-Crafts acylation of diphenyl ether. Synthesis of 6-bromo-1-(4-phenoxyphenyl)-1-hexanone [15]: In a nitrogen-filled glovebox, 6- bromohexanoyl chloride (0.45 ml, 2.94 mmol) and AlCl 3 (0.390 g, 2.94 mmol) were added to a 20 ml S11

12 vial. Under nitrogen atmosphere, anhydrous dichloromethane (5 ml) then diphenyl ether (0.47 ml, 2.94 mmol) were added via a syringe. After stirring at rt for 24 h, the solution was slowly poured into ice water, extracted with dichloromethane (3 x 15 ml), dried over MgSO 4, filtered, and concentrated using a rotary evaporator. Crude product 15 was isolated as a brown liquid (1.27 g) and used in the next step without further purification. Scheme S16: Reduction of ketone 15 to compound 16. Synthesis of 1-(6-bromohexyl)-4-phenoxybenzene [16]: To a 25 ml round-bottom flask equipped with a reflux condenser was added crude ketone 15 (1.27 g, 3.61 mmol), dichloromethane (5 ml), triethylsilane (Et 3 SiH, 3.75 ml, 23.4 mmol), and trifluoroacetic acid (TFA, 2.68 ml, 36.1 mmol). After refluxing for 16 h, the reaction was slowly quenched by adding 1M NaHCO 3 (10 ml) followed by 1M NaOH (10 ml). The solution was extracted with dichloromethane (3 x 15 ml), washed with brine (1 x 15 ml), dried over MgSO 4, filtered, and concentrated using a rotary evaporator. The product 16 was purified by column chromatography using a 4:1 mixture of hexanes/dichloromethane (0.36 g, 37% yield). Scheme S17: Amination of compound 16 with dimethylamine. Synthesis of 1-(6-N,N-dimethylhexylamine)-4-phenoxybenzene [17]: In a nitrogen-filled glovebox, compound 16 (0.36 g, 1.07 mmol), anhydrous THF (1 ml), and 2M dimethylamine in THF (2.15 ml, 4.31 mmol) were added to a 25 ml round-bottom flask. After stirring at rt for 24 h, the reaction mixture was quenched with 1M NaHCO 3 and extracted with diethyl ether (3 x 20 ml). The combined organic layer was dried over MgSO 4, filtered, and concentrated using a rotary evaporator to yield pure 17 (0.34 g, 100% yield). Scheme S18: Methylation of 17 to prepare quaternary ammonium 18. Synthesis of 1-(6-N,N,N-trimethylhexylammonium)-4-phenoxybenzene [18]: To a 25 ml round-bottom flask was added amine 17 (0.33 g, 1.10 mmol), methyl iodide (0.68 ml, 11.0 mmol), and diethyl ether (1 S12

13 ml). After stirring at rt for 5 h, a white solid precipitated from the solution. The white powder was filtered and dried under vacuum to yield pure 18 in iodide form (63 mg, 13% yield). 7. General procedure for room temperature small molecule stability test A 0.55 M solution of sodium methoxide in DMSO-d 6 and methanol-d 4 was prepared by combining 124 mg of sodium methoxide, 4 ml of DMSO-d 6, and 0.2 ml of methanol-d 4. To a 5 ml vial was added 0.05 mmol of desired model compound, 1 drop of a 0.5M 18-crown-6 ether solution in DMSO-d 6, and 0.07 ml of DMSO-d 6. A portion of the sodium methoxide solution (0.38 ml) was added. The resulting solution was immediately transferred to an NMR tube and 1 H NMR spectrum was recorded (labeled as 0 h). Subsequent NMR spectra were recorded at specified time intervals of 0.5, 1, 2, 3, 4, 5, 6, 8, 10, 13, 16, and 20 h. Percentage of backbone degradation was estimated based on the change in the relative intensity of selected aromatic resonances of the model compounds to the methylene resonance of the 18- crown-6 ether internal standard (at 3.7 ppm, set to an integral value of 10). Percentage of cation degradation was estimated based on the change in the relative intensity of the trimethyl (CH 3 ) 3 resonance of the quaternary ammonium to the methylene resonance of 18-crown-6 internal standard. 8. General procedure for 80 and 100 C small molecule stability tests (for Figures 10 and 12 of manuscript) The same DMSO-d 6 and methanol-d 4 solution of sodium methoxide used for the room temperature experiments was used for the 80 and 100 C experiments. To a 5 ml vial was added 0.05 mmol of desired model compound, 1 drop of a 0.5M 18-crown-6 ether solution in DMSO-d 6, and 0.07 ml of DMSO-d 6. A portion of the sodium methoxide solution (0.38 ml) was added. The resulting solution was immediately transferred to an NMR tube and 1 H NMR spectrum was recorded (labeled as 0 h). Then the NMR tube was placed in an 80 or 100 C oil bath and subsequent NMR spectra were recorded at specified time intervals. Percentage of backbone degradation was estimated based on the change in the relative intensity of selected aromatic resonances of the model compound to the methylene resonance of the 18-crown-6 ether internal standard (at 3.7 ppm, set to an integral value of 10). Percentage of cation degradation was estimated based on the change in the relative intensity of the trimethyl (CH 3 ) 3 resonance of the quaternary ammonium to the methylene resonance of 18-crown-6 internal standard. 9. General procedure for PPO polymer NaOCH 3 alkaline stability test (i.e. condition iv) The same DMSO-d 6 and methanol-d 4 solution of sodium methoxide that was used for the room temperature small molecule stability test was used for condition iv stability test. To a 5 ml vial was added 30 mg of PPO-CH 2 QA or PPO-(CH 2 ) 6 QA and 1.13 ml of DMSO-d 6. A portion of the sodium methoxide solution (0.31 ml) was added and the vial was placed in 80 C oil bath for 72 h. The polymer solutions were then poured into 0.05M HCl solution, stirred, filtered, and vacuum dried. The polymers were then analyzed for molecular weight with GPC. S13

14 10. GPC and NMR data for polymer alkaline stability studies Note: M n = number average molecular weight, M w = weight average molecular weight, and polydispersity index (PDI) = M w /M n Table S1: Molecular weight data for synthesis of alkyl-tethered polysulfones (see Figure 2 of manuscript for structures). Polymer M n (kg/mol) M w (kg/mol) PDI (M w /M n ) PSU PSU-CH 2 Cl PSU-CH 2 OH PSU-CH 2 O-Br PSU-Bpin PSU-OH Not soluble in THF PSU-O-Br Figure S1: GPC curves for alkyl-tethered polysulfones. S14

15 Figure S2: 1 H NMR spectra of (a) PSU, (b) PSU-CH 2 Cl, (c) PSU-CH 2 OH, (d) PSU-CH 2 O-Br, and (e) PSU-CH 2 O-QA. Spectra (a), (b), and (d) are in CDCl 3, and spectra (c) and (e) are in DMSO-d 6 (* in spectrum (e) indicates N,N-dimethylacetamide). Figure S3: 1 H NMR spectra of (a) PSU, (b) PSU-Bpin, (c) PSU-OH, (d) PSU-O-Br, and (e) PSU-O-QA. Spectra (a), (b), and (d) are in CDCl 3, and spectra (c) and (e) are in DMSO-d 6 (* in spectrum (e) indicates N,N-dimethylacetamide). S15

16 Table S2: Observed molecular weights for PSU before and after alkaline tests. Condition M n (kg/mol) M w (kg/mol) PDI PSU a condition i condition ii condition iii a Molecular weight data collected for pristine polymer before alkaline treatment. Figure S4: GPC curves of PSU before and after alkaline treatment. Figure S5: 1 H NMR spectra of PSU before and after alkaline treatment. Note the appearance of new peaks due to degradation products after treatment with 10 equiv. NaOCH 3 /methanol in THF for 14 h at 60 C. All other spectra remained unchanged. S16

17 Table S3: Observed molecular weights for PSU-CH 2 Cl before and after alkaline tests. Condition M n (kg/mol) M w (kg/mol) PDI PSU-CH 2 Cl a condition i condition ii condition iii a Molecular weight data collected for pristine polymer before alkaline treatment. Figure S6: GPC curves of PSU-CH 2 Cl before and after alkaline treatment. Figure S7: 1 H NMR spectra of PSU-CH 2 Cl before and after alkaline treatment. Note the appearance of new peaks due to degradation products after treatment with 10 equiv. NaOCH 3 /methanol in THF for 14 h at 60 C. 1 H NMR remained unchanged after immersion of PSU-CH 2 Cl film in 2M NaOCH 3. PSU- CH 2 Cl after 3 equiv KOH treatment had poor solubility in CDCl 3, and thus is not shown. S17

18 Table S4: Observed molecular weights for PSU-CH 2 F before and after alkaline tests. Condition M n (kg/mol) M w (kg/mol) PDI PSU-CH 2 F a condition i condition ii condition iii a Molecular weight data collected for pristine polymer before alkaline treatment. Figure S8: GPC curves of PSU-CH 2 F before and after alkaline treatment. PSU-CH 2 Cl GPC profile is also included as a reference. Figure S9: 1 H and 19 F NMR spectra of PSU-CH 2 F before and after alkaline treatment. Note the appearance of new peaks due to degradation products after treatment with 10 equiv. NaOCH 3 /methanol in THF for 14 h at 60 C. All 19 F signals remained unchanged, indicating the fluorine remained intact. S18

19 Table S5: Observed molecular weights for PPO before and after alkaline tests. Condition M n (kg/mol) M w (kg/mol) PDI PPO a condition i condition ii condition iii a Molecular weight data collected for pristine polymer before alkaline treatment. Figure S10: GPC curves of PPO before and after alkaline treatment. Figure S11: 1 H NMR spectra of PPO before and after alkaline treatment. unchanged. All spectra remained S19

20 Table S6: Observed molecular weights for PPO-CH 2 Br before and after alkaline tests. Condition M n (kg/mol) M w (kg/mol) PDI PPO-CH 2 Br a condition i Not soluble condition ii condition iii a Molecular weight data collected for pristine polymer before alkaline treatment. Figure S12: GPC curves of PPO-CH 2 Br before and after alkaline treatment. Figure S13: 1 H NMR spectra of PPO-CH 2 Br before and after alkaline treatment. PPO-CH 2 Br after 3 equiv KOH treatment had poor solubility in CDCl 3, and thus is not shown. PPO-CH 2 Br was converted to PPO-CH 2 OCH 3 after 10 equiv NaOCH 3 treatment, as seen by the appearance of the OCH 3 methyl resonance at ppm. S20

21 Table S7: Observed molecular weights for PB before and after alkaline tests. Condition M n (kg/mol) M w (kg/mol) PDI PB a condition i condition ii condition iii a Molecular weight data collected for pristine polymer before alkaline treatment. Figure S14: GPC curves of PB before and after alkaline treatment Figure S15: 1 H NMR spectra of PB before and after alkaline treatment. All spectra remained unchanged. S21

22 Table S8: Observed molecular weights for PBA before and after alkaline tests. Condition M n (kg/mol) M w (kg/mol) PDI PBA a condition i condition ii condition iii a Molecular weight data collected for pristine high molecular weight PBA before alkaline treatment. Figure S16: GPC curves of PBA before and after alkaline treatment. Figure S17: 1 H NMR spectra of PBA before and after alkaline treatment. S22

23 Table S9: Observed molecular weights for SEBS before and after alkaline tests. Condition M n (kg/mol) b M w (kg/mol) c PDI d SEBS a condition i condition ii condition iii a Molecular weight data collected for pristine polymer before alkaline treatment. Figure S18: GPC curves of SEBS before and after alkaline treatment. Figure S19: 1 H NMR spectra of SEBS before and after alkaline treatment. unchanged. All spectra remained S23

24 Table S10: Observed molecular weights for SEBS-CH 2 Cl before and after alkaline tests. Condition M n (kg/mol) b M w (kg/mol) c PDI d SEBS-CH 2 Cl a condition i condition ii condition iii a Molecular weight data collected for pristine polymer before alkaline treatment. Figure S20: GPC curves of SEBS-CH 2 Cl before and after alkaline treatment. The GPC profile of SEBS is included for reference. Figure S21: 1 H NMR spectra of SEBS-CH 2 Cl before and after alkaline treatment. The structure of the broad resonance at 3.30 ppm (labeled *) is unknown; it was probably caused by a side reaction during chloromethylation and its intensity has increased after alkaline treatment. S24

25 11. NMR spectra for small molecule stability studies Note: all NMR spectra taken in DMSO-d 6 were referenced to the residual solvent peak at 2.49 ppm in 1 H NMR and at 39.5 ppm in 13 C NMR. Stability studies were taken using a relaxation delay of 5 sec. Figure S22: 1 H NMR spectra of compounds 1 (a), 2 (b), and 8 (c) in DMSO-d 6. Figure S23: 13 C NMR spectrum of compound 1 in DMSO-d 6. S25

26 Figure S24: 1 H NMR spectra for degradation study of compound 1 from 0 to 20 h at room temperature in 4 eq NaOCH 3 in DMSO. Percentage of C O bond degradation was estimated based on the average change in the relative intensity of peaks h and g relative to 18-crown-6. Figure S25: 1 H NMR spectrum for byproduct analysis for compound 1, taken after 20 h of stability test. Suggested byproducts are labeled accordingly. S26

27 Figure S26: (a) Proton decoupled and (b) deuterium decoupled 13 C NMR spectra for byproduct analysis for compound 1, taken after 20 h stability test. Suggested byproducts are labeled accordingly. Figure S27: HSQC NMR spectrum for byproduct analysis for compound 1 taken after 20 h stability test. Suggested byproducts are labeled accordingly. S27

28 Figure S28: (a) GC-MS for the byproduct analysis of compound 1, taken after 20 h stability test. The DMSO NMR sample was treated with 1M HCl and extracted with CHCl 3 before analysis with GC-MS. (b) and (c) show mass spectral data for the observed byproducts. [Note: the structure of compound of (c) has a molecular weight of 248, however the byproduct detected in (c) showed M + = 251. The increase in 3 mass units is a result of the attack of OCD 3 from methanol-d 4 NMR solution instead of OCH 3 ]. Figure S29: 13 C NMR spectrum of compound 2 in DMSO-d 6. S28

29 Figure S30: 1 H NMR spectra for degradation study of compound 2 from 0 to 20 h at room temperature in 4 eq NaOCH 3 in DMSO. Percentage of C O bond degradation was estimated based on the average change in the relative intensity of peaks g, h, and j relative to 18-crown-6. Figure S31: 1 H NMR spectrum for byproduct analysis for compound 2, taken after 20 h of stability test. Suggested byproducts are labeled accordingly. Note that 57% of compound 2 remained after 20 h. S29

30 Figure S32: (a) Proton decoupled and (b) deuterium decoupled 13 C NMR spectra for byproduct analysis for compound 2, taken after 20 h stability test. Suggested byproducts are labeled accordingly. Figure S33: HSQC NMR spectrum for byproduct analysis for compound 2 taken after 20 h stability test. Suggested byproducts are labeled accordingly. S30

31 Figure S34: (a) GC-MS for the byproduct analysis of compound 2, taken after 20 h stability test. The DMSO NMR sample was treated with 1M HCl and extracted with CHCl 3 before analysis with GC-MS. (b) and (c) show mass spectral data for the observed byproducts, whereas (d) shows mass spectrum for remaining compound 2. Figure S35: 13 C NMR spectrum of compound 8 in DMSO-d 6. S31

32 Figure S36: 1 H NMR spectra for degradation study of compound 8 from 0 to 20 h at room temperature in 4 eq NaOCH 3 in DMSO. Percentage of C O bond degradation was estimated based on the average change in the relative intensity of peaks e and h relative to 18-crown-6. Note the rapid decrease in intensity of peak m as a result of H/D exchange. For percentage of degradation of the cation functional group, the change in relative intensity of peak n was used relative to 18-crown-6. Figure S37: 1 H NMR spectrum for byproduct analysis for compound 8, taken after 20 h of stability test. Suggested byproducts are labeled accordingly. S32

33 Figure S38: (a) Proton decoupled and (b) deuterium decoupled 13 C NMR spectra for byproduct analysis for compound 8, taken after 20 h stability test. Suggested byproducts are labeled accordingly. Note evidence of H/D exchange at the benzylic position (peak q). Peak q at 71 ppm shows splitting in (a) due to C D coupling, but converges into a single peak in (b) when running deuterium decoupled 13 C NMR. Figure S39: HSQC NMR spectrum for byproduct analysis for compound 8 taken after 20 h stability test. Suggested byproducts are labeled accordingly. S33

34 Figure S40: (a) GC-MS for the byproduct analysis of compound 8, taken after 20 h stability test. The DMSO NMR sample was treated with 1M HCl and extracted with CHCl 3 before analysis with GC-MS. (b) and (c) show mass spectral data for the observed byproducts. Figure S41: 1 H NMR spectra of compounds 1 (a), 3 (b), and 9 (c) in DMSO-d 6. S34

35 Figure S42: 13 C NMR spectrum of compound 3 in DMSO-d 6. Figure S43: 1 H NMR spectra for degradation study of compound 3 from 0 to 20 h at room temperature in 4 eq NaOCH 3 in DMSO. Percentage of C O bond degradation was estimated based on the change in the relative intensity of peak g relative to 18-crown-6. S35

36 Figure S44: 1 H NMR spectrum for byproduct analysis for compound 3, taken after 20 h of stability test. Suggested byproducts are labeled accordingly. Figure S45: (a) Proton decoupled and (b) deuterium decoupled 13 C NMR for byproduct analysis for compound 3, taken after 20 h stability test. Suggested byproducts are labeled accordingly. S36

37 Figure S46: HSQC NMR spectrum for byproduct analysis for compound 3 taken after 20 h stability test. Suggested byproducts are labeled accordingly. Figure S47: (a) GC-MS for the byproduct analysis of compound 3, taken after 20 h stability test. The DMSO NMR sample was treated with 1M HCl and extracted with CHCl 3 before analysis with GC-MS. (b) and (c) show mass spectral data for the observed byproducts. S37

38 Figure S48: 13 C NMR spectrum of compound 9 in DMSO-d 6. Figure S49: 1 H NMR spectra for degradation study of compound 9 from 0 to 20 h at room temperature in 4 eq NaOCH 3 in DMSO. Percentage of C O bond degradation was estimated based on the average change in the relative intensity of peaks g, h, and k relative to 18-crown-6. Note the rapid decrease in intensity of peak j as a result of H/D exchange. For percentage of degradation of the cation functional group, the change in relative intensity of peak i was used relative to 18-crown-6. S38

39 Figure S50: 1 H NMR spectrum for byproduct analysis for compound 9, taken after 20 h of stability test. Suggested byproducts are labeled accordingly. Figure S51: (a) Proton decoupled and (b) deuterium decoupled 13 C NMR spectra for byproduct analysis for compound 9, taken after 20 h stability test. Suggested byproducts are labeled accordingly. S39

40 Figure S52: HSQC NMR spectrum for byproduct analysis for compound 9 taken after 20 h stability test. Suggested byproducts are labeled accordingly. Figure S53: (a) GC-MS for the byproduct analysis of compound 9, taken after 20 h stability test. The DMSO NMR sample was treated with 1M HCl and extracted with CHCl 3 before GC-MS analysis. (b) shows the mass spectrum for the observed byproducts. S40

41 Figure S54: 1 H NMR spectra of compounds 10 (a), 11 (b), and 14 (c) in DMSO-d 6. Figure S55: (a) GC-MS and (b) 13 C NMR spectrum of pure compound 10 in DMSO-d 6. S41

42 Figure S56: 1 H NMR spectra for degradation study of compound 10 from 0 to 792 h at 100 C in 4 eq NaOCH 3 in DMSO. Percentage of C O bond degradation was estimated based on the average change in the relative intensity of peaks b, e, and f relative to 18-crown-6. Note the decrease in intensity of peaks c and d were a result of H/D exchange. Figure S57: 1 H NMR spectrum for byproduct analysis for compound 10, taken after 792 h at 100 C of stability test. Note that no byproducts were identified; only unreacted starting compound 10 was isolated. S42

43 Figure S58: (a) Proton decoupled and (b) deuterium decoupled 13 C NMR spectra for byproduct analysis for compound 10, taken after 792 h stability test after CDCl 3 extraction. Note the evidence of H/D exchange in peaks c and d. Figure S59: HSQC NMR spectrum for byproduct analysis for compound 10 taken after 792 h stability test. S43

44 Figure S60: (a) GC-MS for the byproduct analysis of compound 10, taken after 792 h stability test. The DMSO NMR sample was treated with 1M HCl and extracted with CHCl 3 before analysis with GC-MS. (b), (c), and (d) show mass spectral data for the observed byproducts. Figure S61: 13 C NMR spectrum of compound 14 in DMSO-d 6. S44

45 Figure S62: 1 H NMR spectra for degradation study of compound 14 from 0 to 96 h at 100 C in 4 eq NaOCH 3 in DMSO. Percentage of C O bond degradation was estimated based on the average change in the relative intensity of peaks e and f relative to 18-crown-6. Note the immediate loss in signal for quaternary ammonium peak i after 3 h due to rapid cation degradation. Figure S63: 1 H NMR spectra for degradation study of compound 14 from 0 to 48 h at 80 C in 4 eq NaOCH 3 in DMSO. Percentage of C O bond degradation was estimated based on the average change in the relative intensity of peaks e and f relative to 18-crown-6. Note the loss in signal for h was a result of H/D exchange. For percentage of degradation of the cation functional group, the change in relative intensity of peak i was used relative to 18-crown-6. S45

46 Figure S64: 1 H NMR spectrum for byproduct analysis for compound 14, taken after 48 h at 80 C of stability test. Suggested byproducts are labeled accordingly. Figure S65: (a) Proton decoupled and (b) deuterium decoupled 13 C NMR spectra for byproduct analysis for compound 14, taken after 48 h at 80 C stability test after CDCl 3 extraction. Note the evidence of H/D exchange in peaks h and i. S46

47 Figure S66: HSQC NMR spectrum for byproduct analysis for compound 14 taken after 48 h stability test at 80 C. Figure S67: (a) GC-MS for the byproduct analysis of compound 14, taken after 48 h at 80 C stability test. The DMSO NMR sample was treated with 1M HCl and extracted with CHCl 3 before analysis with GC-MS. (b) and (c) show mass spectral data for the observed byproducts. We were unable to identify the byproduct in (b). S47

48 Figure S68: Chromatogram from LC-MS for the byproduct analysis of compound 14, taken after 48 h at 80 C stability test. The first peak at 5.98 min was identified as the dimethylamine-containing byproduct, which matched with that identified in Figure S67c. LC-MS confirmed incorporation of at least five deuterium. The second peak at min was a high molecular weight compound which cannot be identified. Figure S69: 1 H NMR spectra of compounds 15 (a), 16 (b), and 17 (c) in CDCl 3, and 18 (d) in DMSO-d 6. S48

49 Figure S70: HMQC spectrum of compound 18 in DMSO-d 6. Figure S71: 1 H NMR spectra for degradation study of compound 18 from 0 to 48 h at 80 C in 4 eq NaOCH 3 in DMSO. Percentage of C O bond degradation was estimated based on the average change in the relative intensity of peaks b and a relative to 18-crown-6. For percentage of degradation of the cation functional group, the change in relative intensity of peaks n and o were used relative to 18-crown-6. S49

50 Figure S72: 1 H NMR spectrum for byproduct analysis for compound 18, taken after 48 h at 80 C of stability test. Suggested byproducts are labeled accordingly. Figure S73: 13 C NMR spectrum for byproduct analysis for compound 18, taken after 48 h at 80 C stability test. Suggested byproducts are labeled accordingly. S50

51 Figure S74: HMQC NMR spectrum for byproduct analysis for compound 18 taken after 48 h stability test at 80 C. Figure S75: (a) GC-MS for the byproduct analysis of compound 18, taken after 48 h at 80 C stability test. The DMSO NMR sample was treated with 1M HCl and extracted with CHCl 3 before analysis with GC-MS. (b) and (c) show mass spectral data for the observed byproducts. S51

52 Table S11: Observed molecular weights for PPO-(CH 2 ) 6 Br before and after alkaline test. Condition M n (kg/mol) M w (kg/mol) PDI PPO-(CH 2 ) 6 Br a condition ii a Molecular weight data collected for pristine PPO-(CH 2 ) 6 Br before alkaline treatment. Figure S76: GPC curves of PPO-(CH 2 ) 6 Br before and after alkaline treatment of condition ii. Figure S77: 1 H NMR spectra of PPO-(CH 2 ) 6 Br before and after alkaline treatment. PPO-(CH 2 ) 6 Br was converted to PPO-(CH 2 ) 6 OCH 3 after 10 equiv NaOCH 3 treatment, as seen by the appearance of the OCH 3 methyl resonance at 3.30 ppm. S52

53 Table S12: Observed molecular weights for PPO-CH 2 QA and PPO-(CH 2 ) 6 QA before and after alkaline tests. Condition M n (kg/mol) M w (kg/mol) PDI PPO-CH 2 Br a PPO-CH 2 QA after condition iv b PPO-(CH 2 ) 6 Br c PPO-(CH 2 ) 6 Br after condition iv d a Molecular weight data collected for pristine PPO-CH 2 Br before alkaline treatment. b Molecular weight data collected for PPO-CH 2 QA after alkaline treatment using condition iv. c Molecular weight data collected for pristine PPO-(CH 2 ) 6 Br before alkaline treatment. d Molecular weight data collected for PPO- (CH 2 ) 6 QA after alkaline treatment using condition iv. Figure S78: GPC curves of PPO-CH 2 Br (red solid line) and PPO-(CH 2 ) 6 Br (blue dashed line) before alkaline treatment, and PPO-CH 2 QA (orange solid line) and PPO-(CH 2 ) 6 QA (purple dashed line) after alkaline treatment of condition vi. Alkaline treated polymers were precipitated from their alkaline solutions into 1M HCl to isolate the polymers and neutralize unreacted base before analysis with GPC. Insoluble parts were filtered and removed from the GPC solutions (prepared in THF). S53

54 12. Computational simulation details and data DFT calculations were performed by Gaussian 09 program. 9 Geometrical parameters for all stationary points (reactants, intermediates, transition states and products) were optimized and additional frequency calculations were performed for all the stationary points to verify whether they are minima or transition states. For DFT calculations, we employed M06-2X 10 functional in conjunction with 6-31+G(d) basis sets. Solvent effects were taken into consideration by the SMD model. 11 DMSO for 1, 2, 8, 14 and THF for 2-Cl, 2-F were used in the SMD calculations for consistency with experiment. Free energies were evaluated at the standard conditions (1 atm and 298 K). Degradation of the polymer backbone having aryl ether bonds by a base such as OH - has been studied theoretically in a paper published by one of the authors. 12 The degradation by the base corresponds to nucleophilic aromatic substitution reactions (SnAr) where the reaction, in many cases, proceeds via two transition states. 13 SnAr starts with the attack of a nuchleophile on the aromatic ring of the polymer which leads to an intermediate (Meisenheimer complex) via transition state involving bond formation between the base and the aromatic ring (Scheme S19). Scheme S19. Mechanism of nucleophilic aromatic substitution (SnAr). Then, a leaving group is detached from the intermediate via another transition state. We already observed 12 that the former transition state is a rate determining step in case of the aryl ether bond cleavage, so that the barrier height for the former transition state should correlate with the experimental degradation rate (the higher the barrier is, the slower the degradation rate is). Therefore, we report herein free energies related to the former transition states. It should be noted that, for 14, the Meisenheimer complex has not been formed which indicates that the formation of the aryl-och 3 bond and the detachment of the leaving group occurs in a concerted manner. S54

55 Figure S79: Molecular structures and NBO charge of (a) 2-Cl and (b) 2-F. S55