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RISS 인기검색어
- 검색키워드
- 저자 : Hanmo Yang (검색결과 4 건)
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Ahmed, Faiz,Sutradhar, Sabuj Chandra,Ryu, Taewook,Jang, Hohyoun,Choi, Kunyoung,Yang, Hanmo,Yoon, Sujin,Rahman, Md. Mahbubur,Kim, Whangi Pergamon Press 2018 International journal of hydrogen energy Vol.43 No.10
<P><B>Abstract</B></P> <P>Branched and linear sulfonated poly(phenylene)s (BSPs and LSPs, respectively) polymer electrolyte membranes (PEMs) containing benzophenone moiety were successfully synthesized and the performance of the LSPs and BSPs were compared in conjunction with Nafion 211<SUP>®</SUP>. The LSPs and BSPs were synthesized by the CC coupling polymerization reaction between 1,4-dichloro-2,5-dibenzoylbenzene (PBP) and 1,4-dichloro-2-benzoylbenzene, and from PBP, 1,4-dichloro-2-benzoylbenzene, and 1,3,5-trichlorobenzene (branching agent), respectively. The degree of sulfonation in both LSPs and BSPs were controlled by varying the concentrations of chlorosulfonic acid and the structures of the resultant PEMs were confirmed by <SUP>1</SUP>H-NMR spectroscopy. The optimal LSP (LSP-2) and BSP (BSP-2) PEMs showed excellent chemical stability due to the absence of ether linkages in the polymer backbone, while the BSP-2 exhibited better proton conductivity (94.6 mS/cm under 90% relative humidity at 80 °C), water resistivity, and lower dimensional changes compared to the LSP-2, which is comparable to Nafion 211<SUP>®</SUP>. The maximum power density for BSP-2 and LSP-2 were 0.60 and 0.49 W/cm<SUP>2</SUP>, respectively, while it was 0.62 W/cm<SUP>2</SUP> for Nafion 211<SUP>®</SUP>. Membrane properties were studied with regard to ion exchange capacity, dimensional stability, proton conductivity, thermogravimetric analysis, and water uptake. The surface morphology of membranes was also analyzed by atomic force microscope.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Branched and linear sulfonated (BSP and LSP, respectively) polymer electrolyte membranes (PEMs) were synthesized. </LI> <LI> The properties and the performance of the synthesized PEMs were compared in conjunction with Nafion 211<SUP>®</SUP>. </LI> <LI> The optimal BSP showed better proton conductivity, physical, and chemical stability than LSPs. </LI> <LI> The power density in fuel cells based on optimized BSP, LSP, and Nafion 211<SUP>®</SUP> were 0.60, 0.49 and 0.62 W/cm<SUP>2</SUP>, respectively. </LI> </UL> </P>
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Ryu, Taewook,Ahmed, Faiz,Sutradhar, Sabuj Chandra,Lopa, Nasrin Siraj,Yang, Hanmo,Yoon, Soojin,Lee, Seungchan,Choi, Inhwan,Kim, Whangi Elsevier 2018 International journal of hydrogen energy Vol.43 No.26
<P><B>Abstract</B></P> <P>The grafted block copolymer based polymer electrolyte membrane (PEM) was successfully synthesized by the superacid-catalyzed polyhydroxyalkylation reaction from biphenyl, 2,2′-biphenol and isatin and the performance of the block copolymer were compared in conjunction with the random copolymer. These polymers have all carbon-carbon structure on polymer backbone without ether linkage. The bromoalkylsulfone potassium salt was prepared from 1,3-propane sultone and potassium bromide. Particularly, the attached alkyl sulfone groups were afforded better stability due to less reactivity towards nucleophilic substitution reaction. Moreover, the block copolymer exhibited better proton conductivity (76.84 mS/cm under 90% relative humidity at 80 <SUP>°</SUP>C), water resistivity, chemical, and thermal stability compared to the random copolymer, because block copolymer membranes showed good hydrophilic/hydrophobic phase separation and wide ionic channels. The structures of the resultant PEMs were confirmed by <SUP>1</SUP>H NMR spectroscopy and thermogravimetric analysis (TGA). These membranes were studied by proton conductivity, water uptake (WU), and ion exchange capacity (IEC). Fenton test was attended by Fenton's reagent (4 ppm Fe<SUP>2+</SUP>, 3% H<SUB>2</SUB>O<SUB>2</SUB>) for confirmation of the polymer degradation and the surface morphology of membranes was also analyzed by atomic force microscope.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The grafted block copolymer was synthesized via super acid catalyzed reaction. </LI> <LI> The properties of the block copolymer were compared in conjunction with random copolymer. </LI> <LI> Block copolymer exhibited better cell performance compared to random copolymer. </LI> <LI> Grafted block copolymer showed 18.75% water uptake. </LI> </UL> </P>
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Synthesis and characterization of fluorosulfonyl imide isatin biphenylene block copolymer for PEMFC
Ryu, Taewook,Chandra, Sabuj Sutradhar,Ahmed, Faiz,Lopa, Nasrin Siraj,Yoon, Soojin,Yang, Hanmo,Lee, Seungchan,Choi, Inhwan,Kim, Whangi Elsevier 2018 International journal of hydrogen energy Vol.43 No.26
<P><B>Abstract</B></P> <P>In this study, A fluorosulfonyl imide-containing precursor derived from fluorosulfonyl isocyanate was synthesized and grafted on poly (isatin-biphenylene) random and block copolymers. The carbon-carbon structured poly (isatin biphenylene)s were prepared by super acid catalyzed polyhydroxyalkylation reaction with istain, 2,2′-biphenyl, 2,2′-dihydroxybiphenyl. A fluorosulfonyl imide-containing precursor was prepared from chlorosulfuric acid and fluorosulfonylisocyanate. Fluorosulfonyl imide group have higher acidity than sulfonic acid group, therefore the membranes containing fluorosulfonyl imide groups instead of sulfonic acid groups were studied. These membranes showed slightly higher performance of proton conductivity, low water uptake, and good dimensional stability. The structure of the synthesized polymer was investigated by <SUP>1</SUP>H NMR spectroscopy. Surface morphologies will also be assessed by atomic force microscope (AFM). Microphase-separated block copolymers are preferred over random copolymers.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Block and random copolymers were synthesized from biphenyl, 2,2′-biphenol and isatin via super acid catalyzed. </LI> <LI> Fluorosulfonyl imide super strong acid was grafted on copolymers instead of sulfonic acid. </LI> <LI> Block copolymer showed better proton conductivity, physical, and chemical stability than random copolymer. </LI> <LI> Block copolymer showed the IEC and water uptake value 1.45 meq./g and 19.14% respectively. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Random and block copolymers successfully synthesized from isatin, biphenyl and 2.2′-biphenol with super acid catalyst. Block copolymer membranes show higher proton conductivity than random copolymers. The block copolymer showed the IEC value 1.45 meq./g, water uptake 19.14% and the proton conductivity 78.89 mS/cm at 80 °C under 90% RH. Block copolymer membrane showed a greater dependence of proton conductivity on the relative humidity, and had higher conductivity and cell performance than that of random copolymer with similar IEC value. These results showed that the morphology of polymer matrix greatly affected the cell performance and membrane with well-separated hydrophilic/hydrophobic phase is very important in the fuel cell application. This research demonstrated the possibility of promising BPIIB membranes for excellent proton conductivity and cell performance.</P> <P>[DISPLAY OMISSION]</P>
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