High Hydroxide-Conducting Polymer Electrolyte Membranes from Aromatic ABA Triblock Copolymers

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1 Supporting informtion High Hydroxide-Conducting Polymer Electrolyte Membrnes from Aromtic ABA Triblock Copolymers Qing Li, Lei Liu, Qingqing Mio, b Bngkun Jin* nd Ruke Bi* CAS Key Lbortory of Soft Mtter Chemistry, Deprtment of Polymer Science nd Engineering, University of Science nd Technology of Chin, Hefei , P. R. Chin. b CAS Key Lbortory of Soft Mtter Chemistry, Deprtment of Chemistry, University of Science nd Technology of Chin, Hefei , P. R. Chin. E-mil: birk@ustc.edu.cn Experimentl Section Mterils Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) ws supplied by the Institute of Chemicl Engineering of Beijing (Chin). 4,4 -Difluorodiphenyl sulfone (FPS), bisphenol A (BPA), dimethylmino pridine (DMAP), CuCl, 2,2 -zobisisobutyronitrile (AIBN), N-bromosuccinimide (NBS), N-methyl-2-pyrrolidone (NMP), N,N-dimethylformmide (DMF), chlorobenzene, toluene, methnol, tetrhydrofurne (THF), chloroform nd potssium crbonte (K 2 CO 3 ) were used s purchsed. AIBN ws dissolved in boiled methnol, then recrystllized in n ice bth nd dried t room temperture under vcuum. CuCl ws dissolved in strong HCl, precipitted by dilution with wter nd filtered off. The precipitte ws wshed with ethnol nd diethyl ether, then dried nd stored in vcuum desicctor. Synthesis of OH-terminted poly(rylene ether sulfone)s (HO-PAES-OH) Into three-neck flsk equipped with mgnetic stirrer, Den Strk trp, nd n rgon gs inlet were dded 46 mmol of FPS, 48 mmol of BPA, nd 60 mmol of K 2 CO 3. Then, 60 ml of NMP nd 30 ml of toluene were chrged into the rection flsk under n rgon tmosphere nd the rection mixture ws heted to 140 o C. After dehydrtion nd removl of toluene for 4 hours, the rection temperture ws incresed to bout 170 o C. The rection ws mintined t 170 C for 20 h, then ws cooled to room temperture nd poured into lrge excess of deionized wter

2 cidified with HC1 under vigorous stirring. The precipitte ws wshed thoroughly with wter nd ethnol severl times, nd dried under vcuum t 60 C for 24 h. Yield: 97%. Synthesis of triblock copolymers contining poly(2,6-dimethyl-1,4-phenylene oxide) nd poly(rylene ether sulfone)s (PPO-PAES-PPO). The following represents typicl procedure for the synthesis of PPO-PAES-PPO-0.38 (0.38 represents the weight rtio of PPO to PAES). HO-PAES-OH (2.11 g), PPO (0.8 g), DMAP (0.186 g) nd CuCl (0.096 g) were dded into the rection flsk under n rgon tmosphere. The rection ws strted by the ddition of chloroform (60 ml). After rection during 1 week t room temperture, the rection mixture ws poured into methnol. The obtined precipitte ws wshed thoroughly with methnol nd wter severl times nd dried in vcuum oven t 60 C for 24 h. Yield: 92% Synthesis of brominted triblock copolymers (BPPO-PAES-BPPO) A typicl synthetic procedure for BPPO-PAES-BPPO-0.38 s follows: PPO-PAES-PPO-0.38 (1.5 g, c. 3.4 mmol of PPO repet units) ws dissolved in chlorobenzene (40 ml) nd then, NBS (1.6 g, 9 mmol) nd AIBN (0.3 g) were dded. The mixture ws heted t reflux conditions (135 C) for 4 h. After cooling, the rection mixture ws poured into methnol to precipitte the product. The polymer ws filtered nd wshed with methnol, nd the residue subsequently ws redissolved in chloroform (120 ml) nd precipitted into methnol. The polymer ws collected nd dried in vcuum oven t 45 C for 24 h, the degree of bromomethyltion: Yield: 94%. Membrne preprtion nd quterniztion BPPO-PAES-BPPO polymers were dissolved in chlorobenzene to form 5 wt % solutions. The solutions were cst onto glss dish nd dried t 60 o C for 24 h to form trnsprent nd tough membrnes. The membrnes were immersed in 30 wt % trimethylmine queous solution t room temperture for 48 h for the quterniztion rection. The quternry mmonium triblock copolymer membrnes were wshed with wter severl times nd immersed in 1 M NOH t room temperture for 48 h to obtin the hydroxide conductive QPPO-PAES-QPPO membrnes (thickness: 30 ± 5 μm). They were then wshed thoroughly with deionized wter nd stored in closed vessel filled with deionized wter. Chrcteriztion NMR spectr were recorded on Bruker AVANCEⅡ spectrometer with TMS s n internl

3 stndrd. Therml nlysis ws crried out on NETZSCH STA 449F3 thermogrvimetric nlyzer (TGA). Smples were heted from 50 to 800 o C t heting rte of 10 o C /min under nitrogen flow. Tensile mesurements of fully humidified membrnes were crried out using Q800 dynmic mechnicl nlyzer (DMA, TA Instruments) t stretch rte of 0.5 N/min t room temperture. The cross sectionl re of the smples is bout 0.40 mm 2. Stress-strin curves were recorded nd tensile modulus ws determined from the slope of the initil, liner portion of the stress-strin curve. Tpping mode tomic force microscopy (AFM) observtions were performed with veeco diinnov SPM, using micro-fbricted Cntilevers with force constnt of pproximtely 20 N/m. Smll-ngle X-ry scttering (SAXS) ws mesured for the dry triblock copolymer membrnes experiments t room temperture. SAXS experiments were performed t the bemline BL16B1 of Shnghi Synchrotron Rdition Fcility (SSRF) (wvelength, λ=0.124 nm). Two-dimensionl SAXS ptterns were obtined using Mr165 CCD detector ( pixels with pixel size of 80 μm). The effective scttering vector (q) were clculted from the scttering ngles (θ) using (q = 4πsin2θ/λ), where λ nd 2θ re the incident wvelength nd totl scttering ngle, respectively. Where λ is the wvelength nd 2θ is the scttering ngle. The Brgg distnce d is relted to q, d = 2π/q. The moleculr weight nd moleculr weight distribution of the polymers were mesured on Wters gel permetion chromtogrphy (GPC) system, which ws equipped with Wters 1515 HPLC solvent pump, Wters 2414 refrctive index detector, nd three Wters Styrgel high-resolution columns t 40 C using HPLC grde chloroform s eluent t flow rte of 1.0 ml/min. Monodispersed polystyrenes were used to generte the clibrtion curve. Hydroxide conductivity The ionic conductivities of the membrnes were mesured using the commonly encountered four-point probe technique. The impednce ws recorded using n Autolb PGSTAT 30 (Eco Chemie, Netherlnd) t glvnosttic mode with current mplitude of 0.1 ma over frequencies rnging from 1 MHz to 50 Hz. Bode plots were used to determine the frequency region over which the the mgnitude of the impednce ws constnt, nd the ionic resistnce ws then obtined from the ssocited Nyquist plot (Fig. S5). The membrne being studied ws set into

4 Teflon cell where it ws in contct with 2 current collecting electrodes nd 2 potentil sensing electrodes (the distnce between the potentil sensing electrodes ws 1 cm). The cell ws completely immersed in deionized wter nd the impednce spectrum ws collected. This ws done quickly to minimize the potentil error cused by rection of the hydroxide ions in the membrne with dissolved crbon dioxide (resulting in the formtion of crbonte/bicrbonte nions nd reduced membrne conductivity). The ionic conductivity ws clculted ccording to the following eqution: σ= L RWd (1) where R is the obtined membrne resistnce, L is the distnce between potentil-sensing electrodes (here 1 cm), nd W nd d re the width (here 1 cm) nd thickness of the membrne, respectively. Ion exchnge cpcity (IEC) IEC ws mesured using stndrd bck titrtion methods. The membrnes in OH - form were immersed in 100 ml of 0.1 M HCl stndrd solution for 24 h. The solutions were then titrted with stndrdized NOH solution using phenolphthlein s n indictor. The IEC vlue ws clculted using the eqution: IEC = V0,NOH C NOH - Vx,NOHCNOH (2) m dry where V 0,NOH nd V x,noh re the volume of the NOH consumed in the titrtion without nd with membrnes, respectively, C NOH is the mole concentrtion of the stndrdized NOH solution, nd m dry is the mss of the dry membrnes. Three replictes were conducted for ech smple. Wter uptke nd swelling rtio The wter uptke vlues were determined for ll the membrnes in their OH - forms. The membrnes were dried in vcuum oven t 80 C to obtin constnt dry weight. The dry membrne smples were soked in the deionized wter t given temperture for 24 h. The hydrted polymer membrnes were tken out, wiped with tissue pper, nd quickly weighed on microblnce. The wter uptke vlues of membrnes were clculted ccording to

5 Wwet -Wdry Wter uptke (%) = 100 (3) W dry Where W dry nd W wet re the weight of the dry nd wter-swollen membrnes, respectively. The number of bsorbed wter molecules per mmonium group (λ) ws clculted ccording to Wter uptke λ = IEC (4) The swelling rtio ws chrcterized by liner expnsion rtio, which ws determined by the difference between wet nd dry dimensions in the length or thickness direction of membrne smple. The swelling rtio ws clculted from lwet -ldry Swelling rtio () % = 100 (5) l dry Where l wet nd l dry re the dimensions of wet nd dry membrnes, respectively. Fig. S1 1 H NMR spectrum of HO-PAES-OH in CDCl 3.

6 Fig. S2 1 H NMR spectr of () PPO-PAES-PPO-0.38 nd (b) BPPO-PAES-BPPO-0.38 in CDCl 3. Tble S1. Moleculr weights nd moleculr weight distributions of triblock copolymers. smple M n, GPC M w, GPC M w, GPC / M n, GPC (g/mol) (g/mol) HO-PAES-OH PPO-PAES-PPO PPO-PAES-PPO PPO-PAES-PPO Determined by GPC.

7 Fig. S3 Representtive GPC trces of HO-PPO-OH nd PPO-PAES-PPO Tble S2. Solubility of HO-PAES-OH, PPO, PPO-PAES-PPO nd BPPO-PAES-BPPO. smple H 2 O CHCl 3 THF DMF chlorobenzene HO-PAES-OH PPO PPO-PAES-PPO BPPO-PAES-BPPO , soluble t room temperture;, insoluble. Fig. S4 TGA curves for the QPPO-PAES-QPPO membrnes under N 2 tmosphere.

Fig. S5 Representtive Nyquist plots of Z vs. Z from AC impednce spectroscopy mesurements of the QPPO-PAES-QPPO-0.76 membrne. Fig. S6 The AFM tpping phse imge of QPPO-PAES-QPPO-1.14 Tble S3.

8 Fig. S5 Representtive Nyquist plots of Z vs. Z from AC impednce spectroscopy mesurements of the QPPO-PAES-QPPO-0.76 membrne. Fig. S6 The AFM tpping phse imge of QPPO-PAES-QPPO-1.14 Tble S3. Mechnicl properties of the QPPO-PAES-QPPO membrnes Smple Tensile strength (MP) Tensile modulus (MP) Elongtion t brek (%) QPPO-PAES-QPPO QPPO-PAES-QPPO QPPO-PAES-QPPO Tble S4. The lkline stbility of QPPO-PAES-QPPO-0.38 nd QPPO-1 membrnes in 1 M NOH t 80 o C. Smple OH - conductivity (ms/cm) t 30 o C 0 dys 1 dy 3 dys 5 dys 7 dys 10 dys QPPO QPPO-PAES-QPPO The membrne ws broken into smll pieces, not to mesure.

Supplementary Figures.

Supplementary Figures. Supplementry Figures. c c Supplementry Figure 1 13 C NMR spectrum of representtive smple of PCPC in CDCl 3. The polymer ws purified y using DMS/MeH. CH 2 Cl 2 H 2 DMS Supplementry Figure 2 1 H NMR spectrum