Supporting information of highly sulfonated polymer-grafted graphene oxide composite

membranes for proton exchange membrane fuel cells

Hyunhee Leea, Jusung Hana, Kihyun Kimb, Junghwan Kima, Eunki Kima, Huiseob Shina, and

Jong-Chan Leea,＊

aDepartment of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National

University, 599 Gwanak-ro, Gwanak-gu, Seoul 151-744, Republic of Korea

bSchool of Materials Science and Engineering, Polymer Science and Engineering, Gyeongsang National

University, 501 Jinju-daero, Jinju, 660-701, South Korea

* Corresponding Author: Tel. +82 2 880 7070 / fax: +82 2 880 8899; e-mail: jongchan@snu.ac.kr

Table S1IEC and proton conductivities of the SPAES and composite membranes at 80 ℃.

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Samples IECwa

(meq g-1) Proton conductivity (σ) (mS cm-1)40% RH

50% RH

60% RH

70% RH

80% RH

90% RH

SPAES 1.92 2.68 7.93 18.33 38.57 67.22 97.91SPAES/GO-2.0 1.89 2.05 6.28 16.20 35.35 67.01 114.90SPAES/SATS-GO-1.0 1.94 3.28 9.25 21.97 44.19 80.59 123.71SPAES/SATS-GO-2.0 2.02 4.63 12.24 27.37 52.66 90.00 131.43SPAES/SATS-GO-3.0 2.06 3.18 9.03 21.60 42.96 77.74 118.,91Nafion 117 - 12.70 22.57 35.70 53.05 75.73 107.98

a Measured by a back-titration method.

Fig. S1. FT-IR spectra of GO, SATS, and SATS-GO.

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Fig. S2. Area-based dimensional change of SPAES and composite membranes after being

immersed in deionized water at 25 and 80 for 1 h: (a) SPAES, (b) SPAES/GO-2.0, (c) ℃ ℃

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SPAES/SATS-GO-1.0, (d) SPAES/SATS-GO-2.0, and (e) SPAES/SATS-GO-3.0.

Fig. S3. XPS analysis of GO and SATS-GO. (a) Survey spectrum of GO, (b) S 2p spectra of

GO, (c) C 1s spectra of GO, (d) survey spectrum of SATS-GO, (e) S 2p spectra of SATS-GO,

and (f) C 1s spectra of SATS-GO.

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5

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Fig. S4. Stress-strain curves of the SPAES and composite membranes.

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Fig. S5. TGA curves of GO, SATS, and SATS-GO.

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