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dc.contributor.authorYu, Xiangen_US
dc.date.accessioned2014-03-14T20:08:49Z
dc.date.available2014-03-14T20:08:49Z
dc.date.issued2008-01-21en_US
dc.identifier.otheretd-04032008-043523en_US
dc.identifier.urihttp://hdl.handle.net/10919/26608
dc.description.abstractHydrophilic/hydrophobic block copolymers as proton exchange membranes (PEMs) has become an emerging area of research in recent years. Three series of hydrophilic/hydrophobic, fluorinated/sulfonated multiblock copolymers were synthesized and characterized in this thesis. These copolymers were obtained through moderate temperature (~100°C) coupling reactions, which minimize the ether-ether interchanges between hydrophobic and hydrophilic telechelic oligomers via a nucleophilic aromatic substitution mechanism. The hydrophilic blocks were based on the nucleophilic step polymerization of 3,3â -disulfonated, 4,4â -dichlorodiphenyl sulfone with an excess 4,4â -biphenol to afford phenoxide endgroups. The hydrophobic (fluorinated) blocks were largely based on decafluoro biphenyl (excess) and various bisphenols. The copolymers were obtained in high molecular weights and were solvent cast into tough membranes, which had nanophase separated hydrophilic and hydrophobic regions. The performance and structure-property relationships of these materials were studied and compared to random copolymer systems. NMR results supported that the multiblock sequence had been achieved. They displayed superior proton conductivity, due to the ionic proton conducting channels formed through the self-assembly of the sulfonated blocks. The nano-phase separated morphologies of the copolymer membranes were studied and confirmed by atomic force microscopy. Through control of a variety of parameters, including ion exchange capacity and sequence lengths, performances as high, or even higher than those of the state-of-the-art PEM, Nafion, were achieved.en_US
dc.publisherVirginia Techen_US
dc.relation.haspartFinalXiangYuDissertation.pdfen_US
dc.rightsI hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Virginia Tech or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report.en_US
dc.subjectNanophase separationen_US
dc.subjectMorphologyen_US
dc.subjectPoly(arylene ether sulfone)sen_US
dc.subjectFuel cellsen_US
dc.subjectProton exchange membranesen_US
dc.subjectMultiblock copolymersen_US
dc.subjectFluorinated copolymersen_US
dc.titleSynthesis and Characterization of Hydrophilic-Hydrophobic Disulfonated Poly(Arylene Ether Sulfone)-Decafluoro Biphenyl Based Poly(Arylene Ether) Multiblock Copolymers for Proton Exchange Membranes (PEMs)en_US
dc.typeDissertationen_US
dc.contributor.departmentMacromolecular Science and Engineeringen_US
dc.description.degreePh. D.en_US
thesis.degree.namePh. D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen_US
thesis.degree.disciplineMacromolecular Science and Engineeringen_US
dc.contributor.committeechairMcGrath, James E.en_US
dc.contributor.committeememberDillard, John G.en_US
dc.contributor.committeememberDavis, Richey M.en_US
dc.contributor.committeememberCase, Scott W.en_US
dc.contributor.committeememberRiffle, Judy S.en_US
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-04032008-043523/en_US
dc.date.sdate2008-04-03en_US
dc.date.rdate2008-04-21
dc.date.adate2008-04-21en_US


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