Effect of Annealing of Nafion Recast Membranes Containing Ionic Liquids
1
조회
0
다운로드
6
인용
0
참고문헌
키워드
초록
The composite membranes comprising of sulfonated polymers as matrix and ionic liquids as ion-conducting medium in replacement of water are studied to investigate the effect of annealing of the sulfonated polymers. The polymeric membranes are prepared on recast Nafion containing the ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4). The composite membranes are characterized by thermogravitational analyses, ion conductivity and small-angle X-ray scattering. The composite membranes annealed at 190oC for 2 h after the fixed drying step showed better ionic conductivity, but no significant increase in thermal stability. The mean Bragg distance between the ionic clusters, which is reflected in the position of the ionomer peak (small-angle scattering maximum), is larger in the annealed composite membranes containing EMIBF4 than the non-annealed ones. It might have been explained to be due to the different level of ion-clustering ability of the hydrophilic parts (i.e., sulfonic acid groups) in the non- and annealed polymer matrix. In addition, the ionic conductivity of the membranes shows higher for the annealed composite membranes containing EMIBF4. It can be concluded that the annealing of the composite membranes containing ionic liquids due to an increase in ion-clustering ability is able to bring about the enhancement of ionic conductivity suitable for potential use in proton exchange membrane fuel cells (PEMFCs) at medium temperatures (150-200oC) in the absence of external humidification.
Abstract
The composite membranes comprising of sulfonated polymers as matrix and ionic liquids as ion-conducting medium in replacement of water are studied to investigate the effect of annealing of the sulfonated polymers. The polymeric membranes are prepared on recast Nafion containing the ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF4). The composite membranes are characterized by thermogravitational analyses, ion conductivity and small-angle X-ray scattering. The composite membranes annealed at 190oC for 2 h after the fixed drying step showed better ionic conductivity, but no significant increase in thermal stability. The mean Bragg distance between the ionic clusters, which is reflected in the position of the ionomer peak (small-angle scattering maximum), is larger in the annealed composite membranes containing EMIBF4 than the non-annealed ones. It might have been explained to be due to the different level of ion-clustering ability of the hydrophilic parts (i.e., sulfonic acid groups) in the non- and annealed polymer matrix. In addition, the ionic conductivity of the membranes shows higher for the annealed composite membranes containing EMIBF4. It can be concluded that the annealing of the composite membranes containing ionic liquids due to an increase in ion-clustering ability is able to bring about the enhancement of ionic conductivity suitable for potential use in proton exchange membrane fuel cells (PEMFCs) at medium temperatures (150-200oC) in the absence of external humidification.
참고문헌 (21)
- 박진수, "Small-Angle X-ray Scattering Study of Water Free Fuel Cell Membranes Containing Ionic Liquids", CHEMISTRY OF MATERIALS, 22, pp.803~812 (2010), AMER CHEMICAL SOC
- Q. Li, "‘Approachesand Recent Development of Polymer Electrolyte Membranesfor Fuel Cells Operating above 100oC’", J. Chem.Mater, 15, pp.4896~4915 (2003)
- J. Roziere, "Non-fluorinated polymermaterials for proton exchange membrane fuel cells’", Annu.Rev. Mater. Res, 33, pp.503~ (2003)
- E. Cho, "A Study on Proton Conductivity of Composite Membranes with Various Ionic Liquids for High-Temperature Anhydrous Fuel Cells", JOURNAL OF THE ELECTROCHEMICAL SOCIETY, 156(2), pp.197~202 (2009), ELECTROCHEMICAL SOC INC
- S. S. Sekhon, "A SAXS study on nanostructure evolution in water free membranes containing ionic liquid: from dry membrane to saturation", PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 12(41), pp.13763~13769 (2010), ROYAL SOC CHEMISTRY
- 박진수, "Morphology Studies of High Temperature Proton Conducting Membranes Containing Hydrophilic", Hydrophobic Ionic Liquids, 2009, pp.42, 2054~2062[DOI]
- J.-S. Baek, "Preparation and characterization of nonaqueousproton-conducting membranes with the lowcontent of ionic liquids’", Fuel Cells, 10, pp.762~ (2010)
- J. Li, "Durable and highperformance Nafion membrane prepared through hightemperatureannealing methodology’", J. Membr. Sci, 361, pp.38~ (2010)
- C. R. M Robert, "‘Procedure for preparingsolution-cast perfluorosulfonate ionomer films andmembranes’", Anal. Chem, 58, pp.2570~ (1986)
- R. M. R. B. Moore, "Chemical and morphologicalproperties of solution-cast perfluorosulfonate ionomers", Macromolecules, 21, pp.1334~ (1988)
- G. Gebel, "Structure andrelated properties of solution cast perfluorosulfonatedionomer films’", Macromolecules, 20, pp.1425~ (1987)
- Y. H. Luan, "‘Annealing effect of perfluorosulfonated ionomermembranes on proton conductivity and methanol permeability’", J. Appl. Polym. Sci, 107, pp.396~ (2008)
- Y. Woo, "Synthesis andcharacterization of sulfonated polyimide membranes fordirect methanol fuel cell’", J. Membr. Sci, 220, pp.31~ (2003)
- T. D. Gierke, "Themorphology in nafion perfluorinated membrane products,as determined by wide- and small-angle x-ray studies’", J.Polym. Sci.: Polym. Phys. Ed, 19, pp.1687~ (1981)
- B. Dreyfus, "‘Distribution of the « micelles » in hydratedperfluorinated ionomer membranes from SANS experiments’", J. Phys. France, 51, pp.1341~ (1990)
- G. Gebel, "‘Small-Angle Scattering Studyof Water-Swollen Perfluorinated Ionomer Membranes", Macromolecules, 30, pp.7914~ (1997)
- S. Kumar, "Interpretation of small-angle xrayand neutron scattering data for perfluorosulfonatedionomer membranes", J. Polym. Sci. B, 24, pp.1767~ (1986)
- A. S. Ioselevich, "Fine Morphology of Proton-Conducting Ionomers’", J.Phys. Chem. B, 108, pp.11953~ (2004)
- G. Gebel, "Structural evolution of water swollenperfluorosulfonated ionomers from dry membrane tosolution’", Polymer, 41, pp.5829~ (2000)
- L. Rubatat, "Evidenceof Elongated Polymeric Aggregates in Nafion’", Macromolecules, 30, pp.4050~ (2002)
- L. Rubatat, "Structure of Nafion: Matching Fourier and Real SpaceStudies of Corresponding Films and Solutions’", Macromolecules, 37, pp.7772~ (2004)