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1 Korean Chem. Eng. Res., Vol. 44, No. 2, April, 2006, pp l so j i nsk j/ Œ j m m oo Ç q Ç k Çm *Ç qk** n ne k e 56-1 * edš e o 14-1 **l CT l ne e 134 (2005 7o 19p r, o 10p }ˆ) Preparation of Composite Nafion/polyphenylene Oxide(PPO) with Hetropoly Acid(HPA) Membranes for Direct Methanol Fuel Cells Donghyun Kim, Junho Sauk, Hwayong Kim, Kab Soo Lee*Gand Joon Yong Sung** School of Chemical and Biological Engineering, & Institute of Chemical Process, Seoul National Universty, San 56-1, Shinlim-dong, Gwanak-gu, Seoul , Korea *Environmental System Engineering, Kimpo College, San 14-1, Ponae-ri, Wolgot-myun, Gyounggi-do , Korea **Center for Clean Technology, Yonsei University, 134, Chinchon-dong, Seodaemun-gu, Seoul , Korea (Received 19 July 2005; accepted 10 March 2006) k m p (PPO) pn l (HPA)p reˆ rs n q p rs p m. p dšp (PWA)p p (PMA)p PPO p p n l v kp n n l rs m. l l PWA p o n ˆmp PPO p o n p n mp, PPO-PWA nkp o Ž ol r m. p PPO-PWA l m p n l p rs m, rs p pm r m ˆm Œ r l m. PPO-PWA p ˆm s SEM(scanning electron microscopy) EDS(energy dispersive spectrometer) m, p vr ˆm l rv(dmfc)n r v p p e m. PPO-PWA s v p p pn p f DMFC l p ˆm Œ p 66Í tp pl. h Abstract The preparation and characterization of new polymer composite membranes containing polyphenylene oxide (PPO) thin films with hetropoly acid (HPA) are presented. PPO thin films with phosphotungstic acid (PWA) or phosphomolybdic acid (PMA) have been prepared by using the solvent mixture. The PWA and PPO can be blended using the solvent mixture, because PPO and PWA are not soluble in the same solvent. In this study, methanol was used as a solvent dissolving PWA and chloroform was used as a solvent dissolving PPO. PPO-PWA solutions were cast onto a glass plate with uniform thickness. The composite membranes were prepared by casting Nafion mixture on porous PPO-PWA films. The morphology and structure of these PPO-PWA films were observed with scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The composite membranes were characterized by measuring their ion conductivity and methanol permeability. The performance was evaluated with composite membranes as electrolytes in fuel cell conditions. The methanol cross-over of composite membranes containing PPO-PWA barrier films in the DMFC reduced by 66Í. Key words: Polyphenylene Oxide, Hetropoly Acid, Phosphotungstic Acid, PPO-PWA Films, Direct Methanol Fuel Cells, Methanol Cross-over To whom correspondence should be addressed. hwayongk@snu.ac.kr 187

2 188 Ë t Ë nëp Ë tn 1. l rv 2 rvm - r lp, l v v r r l v eˆ tn l v r edšp. l rv p l v r p, rp n p m p p n p n op t p [1-3]. l n l rvp n, dp r q l tp n rrp v pp, ˆmp l n vr ˆm l rv(dmfcs) r k~l p np d edšp l n ro q l rn lv p p. DMFC l ˆmp p ˆ m vr, p ˆmp p l v v }l d, l, qop p p l, DMFC p pp ~r ~ l vop p [4-6]. p DMFCp qrl DMFCp en l v rrp p. p p ˆmp vr q r v p l ˆmp dm (crossover) p. ˆmp dm p r l p ppˆp f r~ l rvp pl ep p [7-9]. l rvl pl q r v p r n p p m p pm q s sp r m n r, r p v qr pv, m p rkp p p ˆmp dm p rr v p l[10,11] ˆm dm p tp p r v l l rp k p. DMFC l ˆm dm p tp o r v rs l p l v l. Kim Yamazaki[12] ˆm Œ tp o ml p d(calcium phosphate)p ~ l r v p rs p rk m, Shao [8]p m k m(pva)p o p n l ˆm dm p tp p ep. Sauk [13]p p p ˆ p pn l DMFC n m/ dˆp p rs m, Hanaka [14]p l Ž - nlž p n l DMFC n t ~ p rs m. (heteropoly acid, HPA) pv el r qn p, ml p k q r v pp p o n l p n v p. p k m p n l p n l n p v p. p l l rvn q r v p p pnl ep km, Li [15]p PVAl PWA ve q r v p rs l m. l l r v p Œ p k q r eˆ o, p dšp (phosphotungstic acid, PWA) p (phosphomolybdic acid, PMA)p q p rs o n n l p reˆ qlp m. ˆm n n l op qlp pl p PPO-HPA p rs m [16-19]. o44 o k l p rp p PWA PPOl re p p n p rs p f rv p ˆm Œ pp t p p. PPO-PWAp s p kp sr rl m, p ˆ o SEM(scanning electron microscopy) n m. pm r m ˆm Œ r m 115 p s l rs PPO-PMA m m (HPA)p dšp (H 3 PW 12, PWA) p (H 3 PMO 12, PMA)p Fluka Chemicalsl mp, p p sep Fig. 1l ˆ l. p HPA rr 300 o C l (calcine)e. m p (PPO, poly-2,6- dimethyl-1,4-phenylene oxide, Aldrich Co) q n m. ˆm(M) (C)p n n m, p rs o p m 15 wtí nkp n m m oo HPAm PPO p n l v k l, n n l pl. l l Lee [16]p l q l rp PPO-HPA p rs m, p Fig. 2l ˆ l. p PPO p o n n m. l l p PWAp kp 0.5 gp reˆ, PPO p o p kp sr l e m., ps l p PMA n l pm m. PWA(0.5 g)p 3mlp ˆml m, 0.9 g p PPO 14~20 mlp nkl p l PWA-M nkp PPO-C nkl l tl, PPO-PWA-MC nkp mr v ltl. o Ž ol PPO-PWA nkp p rs mp, PPO-PWA p k ml seˆ, o Ž p o /lˆm k( 1:1)kl 10 k. p 3~4 µm m. p PPO-PWA ol m nkp pn l p r s pl. PPO-PWA p o Ž ol, m Fig. 1. Chemical structure of (a) H 3 PMo 12 (PMA)/H 3 PW 12 (PWA), (b) poly-2,6-dimethyl-1,4-phenylene oxide(ppo).

p ~ p rs 189 Fig. 2. Preparation procedures of Nafion / PPO-HPA composite membranes. p l. o Žp 80 o C m l 8e k se, s rp v ˆp m l r se. n mr v eˆ, m v mr PPO-PWA p. l p p lt o Žp p p l. p 80 o C, 0.

m Š SEM(FE-SEM, JSM-6700F)p n l PPO-PWA p ˆ r p m. r p o p Pt p. rs PPO-PWA p l dš o p p o l EDS p ee m. pm r ml AC r p d (EG&G model 273A potentiostat/galvanost) n l r m.

3 p ~ p rs 189 Fig. 2. Preparation procedures of Nafion / PPO-HPA composite membranes. p l. o Žp 80 o C m l 8e k se, s rp v ˆp m l r se. n mr v eˆ, m v mr PPO-PWA p. l p p lt o Žp p p l. p 80 o C, 0.5 Mp H 2 SO 4 (98Í, Aldrich)p 1e k } tp qn ˆ eˆ pl, ql p r o rs p 80 o C p v l 1e k. p m nkp kp sr l d rl p l. rs PWA-PPO p 3~4 µmp, m/pwa- PPO p 100±5 µm p m Š SEM(FE-SEM, JSM-6700F)p n l PPO-PWA p ˆ r p m. r p o p Pt p. rs PPO-PWA p l dš o p p o l EDS p ee m. pm r ml AC r p d (EG&G model 273A potentiostat/galvanost) n l r m. AC rkp v p 10 mvpmp, l l 4-ˆ p n l l r r p r m. l ˆm Œ pp vr k p pn l ml r m. ˆm Œ pp r (NAR-3T, ATAGO) r l m. p ˆm Œ pp, e l v Œ ˆmp v m ns l rv l r v p p d m. r s l k p p p - r 125 o C, 13.8 MPap k l 2 k mk l rs m [20]. r p v p 4.0 mg/cm 2 p E-TEKl l n m. l rv s p ˆmp 2M, q m 80 o C, k p pp k p 2 kgf/cm 2 plp, p o p v o sr (300 ml/min) sr m PPO-PWA m Š FE-SEM vp l PPO-PWA rp ˆ r m. Fig. 3l PPO-C nkl p Fig. 3. Scanning electron micrographs of (a) 14 ml, (b) 16 ml, (c) 18 ml, (d) 20 ml, amounts of chloroform on PPO-PWA-MC films. kp 14~20 ml eˆ rs PPO-PWA-MC p SEM p v ˆ l. p kp 12 ml p l p rs v p, 14 ml p l p ˆ m. p ˆr p n p v pl p p l, l s v plp, ƒ vp Fig. 4l ˆ l [21]. rs p p kp 14 ml p p q p r l, 16 ml p q p mp, 16 ml p p nl e s p v rs l. Fig. 5(a)l p 16 ml n mp np PPO- Fig. 4. Model for pore formation and PWA distribution through PPO-PWA. Korean Chem. Eng. Res., Vol. 44, No. 2, April, 2006

190 Ë t Ë nëp Ë tn Fig. 5. (a) EDS spectra of PPO-PWA thin films, (b) Cross-sectional EDS image of PPO-PWA thin films by mapping on tungsten(w). PWA l dšp EDS p lt. dš n 1.4, 1.8, 2.

Fig. 6p rs PPO-PWA l m nkp pn l p v rv ee p. rv Fig. 3p ˆ v p kp 16 mlp q sp p ˆ p, p p k p rp n, pl v p m. p p r s PPO-PWA p ˆ l p p lv, p s, r p 16 mlp p ~ PPO-PWA pn m l p n q sp p v p p.

4 190 Ë t Ë nëp Ë tn Fig. 5. (a) EDS spectra of PPO-PWA thin films, (b) Cross-sectional EDS image of PPO-PWA thin films by mapping on tungsten(w). PWA l dšp EDS p lt. dš n 1.4, 1.8, 2.1 KeVl ~ l, p p l dšp sq ppp ˆ. Fig. 5(b)l EDS PPO-PWA p dš ˆ l. p p dšp r~l ~ p ppp p p l PWA q lpp k pl. PMA-PPO p mp l 30e p v ph r m. p ph 5.4m, 30e p v ph r ll p k, PMA n p v k rp r lpp k pl. Fig. 6p rs PPO-PWA l m nkp pn l p v rv ee p. rv Fig. 3p ˆ v p kp 16 mlp q sp p ˆ p, p p k p rp n, pl v p m. p p r s PPO-PWA p ˆ l p p lv, p s, r p 16 mlp p ~ PPO-PWA pn m l p n q sp p v p p. q p sk 16 ml p 0.35 Vl 120 ma r p m 115m kp, v m 115 lv p m. Fig. 7p p dšp p p pn l r PPO-PWAm PPO-PMAp ˆ p. p p s l rs l. p } PPO-PMA p s PPO-PWAp s s p p p pl mj n j j ˆ PWAm PMAp pm r ˆm Œ Table 1l ˆ l. p p p d p m 115m m. m 115l p pm r S/cmm, PWA, PMA pn p m 115 p pm r v, PWA PMA p pm r m. p rs p ˆ l p p, PPO-HPAp s p p p l p p k r p, Fig. 6l p } PPO-PWAp s PPO- PMAp sl p p v k, sp p l r p v e pm r l. Fig. 6. Effect of various amounts of chloroform in composite membranes on performance of single-cell DMFC at 80 o C. o44 o k Fig. 7. Scanning electron micrographs of (a) PPO-PMA, (b) PPO- PWA films.

5 Table 1. Comparison of ion conductivity and methanol permeability of composite membranes at room temperature Type of membranes Ion Conductivity (S/cm) p ~ p rs 191 Methanol Permeability (cm 2 /s) Nafion Nafion/PPO-PMA Nafion/PPO-PWA l r lpp k pl. rv q p s v 16 mlp p n l p rs mp 0.35 Vl 120 ma r q p p m p, p m 115m p tpl. p s l p p p ˆ. PWA PMAl p v, PPOl re p rs n s PMA p s p p o, ˆm Œ m Í tmp, pm r le e rv p v. PMA pn l p rs n pmr eˆv kp ˆm Œ 39Í e m 115 rv p ˆ. PMAm PWA HPA pn l p rs n, ˆm Œ r e m 115m p rv lp pl. y Fig. 8. Single cell DMFC performance of composite membranes at 80 o C. ˆm Œ le m cm 2 /s q k, PPO-PMA 39Í l cm 2 /s, PPO-PWA 66Í l cm 2 /s m. p le p m p p n s v PPO-PWAp n p ˆm Œ v p k pl ns 80 o Cl PPO-PMA, PPO-PWA p DMFC p m 115m l Fig. 8l e m. l ˆ p PPO-PMA p 0.35 Vl 160 ma m Í p p p m, PPO-PWA p m 115m p p m. p PPO-PMAp pm r m v, ˆmp dm p r e ˆm Œ m Í l rv p p. PPO-PWAp nl ˆm Œ r lv, p m r le k rv p p pv. 4. PWA PPOl re p rs, pl m nkp n l p rs m. p s n t PPO p p kp sr p f d rl pl. rs p SEM EDS, 16 mlp p n mp n q p s v, PWA q 1. Smitha, B., Sridhar, S. and Khan, A. A., Synthesis and Characterization of Proton Conducting Polymer Membranes for Fuel Cells, Journal of Membrane Science, 225(1), 63-76(2003). 2. Appleby, A. J. and Foulkes, F. R., Fuel Cell Handbook, Van Nostrand Reinhold, N.Y., 3-7(1989). 3. Yu, J., Yi, B., Xing, D., Liu, F., Shao, Z. and Fu, Y., Degradation Mechanism of Polystyrene Sulfonic Acid Membrane and Application of its Composite Membranes in Fuel Cells, Journal of Power Sources, 4937, 1-6(2002). 4. Jörissen, L., Gogel, V., Kerres, J. and Garche, J., New Membranes for Direct Methanol Fuel Cells, Journal of Power Sources, 105(2), (2002). 5. Kordesh, K. V., 25 Years of Fuel Cell Development, J. Electrochem. Soc., 125(1), 77-91(1978). 6. Vielstich, W., Lamm, A., Gasteiger, H. A., Handbook of Fuel Cells, John Wiley & Sons Ltd., England(2003). 7. Scott, K. and Taama, W., Performance of a Direct Methanol Fuel Cell, J. Appl. Electrochem., 28(3), (1998). 8. Shao, Z.G G., Wang, X. and Hsing, I. M., Composite Nafion/ Polyvinyl Alcohol Membranes for the Direct Methanol Fuel Cell, Journal of Membrane Science, 210(1), (2002). 9. Cruickshank, J. and Scott K., The Degree and Effect of Methanol Crossover in the Direct Methanol Fuel Cell, Journal of Power Sources, 70(1), 40-47(1998). 10. Dimitrova, P., Friedrich, K. A., Stimming, U. and Vogt, B., Modified Nafion -Based Membranes for Use in Direct Methanol Fuel Cells, Solid State Ionics, 150(1), (2002). 11. Dimitrova, P., Friedrich, K. A., Vogt, B. and Stimming, U., Transport Properties of Ionomer Composite Membranes for Direct Methanol Fuel Cells, Journal of Electroanalytical Chemistry, 532(1), 75-83(2002). 12. Kim, Y. S. and Yamazaki, Y., Low Methanol Permeable and High Proton-Conducting Nafion/Calcium Phosphate Composite Membrane for DMFC, Solid Stete Ionics, 176(11), (2005). 13. Sauk, J., Byun, J., Kang, Y. and Kim, H., Preparation of Nafion/ Polystyrene Composite Membranes Using Supercritical CO 2 Impregnation for DMFCs, Korean Chem. Eng. Res., 42(5), 619- Korean Chem. Eng. Res., Vol. 44, No. 2, April, 2006

6 192 Ë t Ë nëp Ë tn 623(2004). 14. Hatanaka, T., Hasegawa, N., Kamiya, A., Kawasumi, M., Morimoto, Y. and Kawahara, K., Cell Performances of Direct Methanol Fuel Cells with Grafted Membranes, Fuel, 81(17), (2002). 15. Li, L., Xu, L. and Wang, Y., Novel Proton Conducting Composite Membranes for Direct Methanol Fuel Cell, Materials Letters, 57(8), (2003). 16. Lee, J. K., Song, I. K. and Lee, W. Y., Design of Novel Catal Yst Imbedding Heteropoly Acids in Polymer Films: Catalytic Activity for Ethanol Conversion, Fuel Journal of Molecular Catalysis A: Chemical, 120(1), (1997). 17. Kozhenvnikov, I. V. and Matveev, K. III., Homogeneous Catalysts Based on Heteropoly Acid, Applied Catalysis, 5(2), (1983). 18. Song, I. K., Lee, J. K. and Lee, W. Y., Preparation and Catalytic Activity of H 3 PMo 12 -Blended Polymer Film for Ethanol Conversion Reaction, Applied Catalysis A, 119(1), (1994). 19. Okuhara, T., Mizuno, N. and Misono, M., Catalytic Chemistry of Heteropoly Compounds, Adv Catal, 41, (1996). 20. Sauk, J., Byun, J. and Kim, H., Grafting of Styrene on to Nafion Membranes Using Supercritical CO 2 Impregnation for Direct Methanol Fuel Cells, Journal of Power Sources, 132(1), (2004). 21. Lee, H. Y. and Song, I. K., Design of Heteropolyacid-imbedded Polymer Films and Catalytic Membranes, HWAHAK KONGHAK, 38(3), (2000). o44 o k

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<30372E31362D323028BDC5C7F6C5C32DB9CCB1B970626D292E666D> k m v r1 r1 16~20 (2009) J. Korean Academy of Managed Care Pharmacy Vol. 1, No. 1 Pharmacy Benefit Management iç 1# x sƒ, 1 w w w Overview on Pharmacy Benefit Management in USA Kyung Eob ChoiGand Hyun