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dc.contributor.advisorHerring, Andrew M.
dc.contributor.authorLiu, Yuan
dc.date.accessioned2007-01-03T07:02:47Z
dc.date.accessioned2022-02-09T08:59:44Z
dc.date.available2015-08-01T04:18:44Z
dc.date.available2022-02-09T08:59:44Z
dc.date.issued2014
dc.date.submitted2014
dc.identifierT 7604
dc.identifier.urihttps://hdl.handle.net/11124/10618
dc.descriptionIncludes bibliographical references.
dc.descriptionIncludes illustrations (some color).
dc.description.abstractIn this thesis we studied the influence of annealing, heteropoy acid (HPA) doping, and side chain chemistry to a perfluorosulfonic acid polymer's (PFSA's) morphology and transport properties. We also investigated the effects of polymer block structure on a co-polyamide material's morphology and proton conduction properties. We demonstrated that proton conductivity can be improved thorough annealing PFSA polymers at higher temperatures, due to the formation of larger ionic clusters: at 95%RH, the radius of gyration of the ionic domains increases from 11.9 Å to 17.1 Å, and the conductivity increases from 0.20 to 0.36 S/cm, as annealing temperature increases from 180 °C to 200 °C. We also observed that Grotthuss hoping can be facilitated by HPA doping: the proton conductivity contributed from Grotthuss hopping increases from 0.10 to 0.15 S/cm for the undoped and 5%HPW doped films. HPAs make the hydrophilic domains more homogeneous by their bridging effect: the tortuosity at maximum humidity decreases from 1.40 to 1.08, upon 5%HPW addition. To create larger ionic domains, bulky, highly flexible, and hydrophilic side chains, with less steric hindrance from protogenic groups are desirable: the 3M PFIA (contains multiple protogenic groups on the side chain), can form larger ionic domains than the 3M PFSA, which has a shorter side chain containing only one photogenic group; the meta bis ionomer forms larger ionic domains than the ortho bis ionomer, resulting from a larger separation distance between the sulfonic group and the imide group, hence less steric hindrance to water uptake. Ordered ionic domains (with inter domain distance ca. 60 Å) were achieved by making a block copolymer. The block copolymer has lower conductivity and smaller water uptake than the random polymer based on the same chemistry. The ionomer peak from the SAXS pattern of the block copolymer becomes less prominent upon hydration, indicating water reaches the polymer matrix.
dc.format.mediumborn digital
dc.format.mediumdoctoral dissertations
dc.languageEnglish
dc.language.isoeng
dc.publisherColorado School of Mines. Arthur Lakes Library
dc.relation.ispartof2010-2019 - Mines Theses & Dissertations
dc.rightsCopyright of the original work is retained by the author.
dc.subject.lcshPolymers
dc.subject.lcshProton exchange membrane fuel cells
dc.subject.lcshMorphology
dc.subject.lcshSolid state proton conductors
dc.titleEffects of pretreatment, heteropoly acid doping, hydration, and membrane chemistries to the morphology and transport properties of proton exchange membranes
dc.typeText
dc.contributor.committeememberMartin, P. A.
dc.contributor.committeememberWolden, Colin Andrew
dc.contributor.committeememberMaupin, C. Mark
dc.contributor.committeememberKnauss, Daniel M.
dcterms.embargo.terms2015-08-01
dcterms.embargo.expires2015-08-01
thesis.degree.nameDoctor of Philosophy (Ph.D.)
thesis.degree.levelDoctoral
thesis.degree.disciplineChemical and Biological Engineering
thesis.degree.grantorColorado School of Mines


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