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AuthorMattea, Carlosdc.contributor.author
Date of accession2016-03-14T13:39:25Zdc.date.accessioned
Available in OPARU since2016-03-14T13:39:25Zdc.date.available
Year of creation2006dc.date.created
AbstractField cycling NMR relaxometry was used to study dynamics of fluids under confinement in different scenarios: fluids flowing through porous media, fluids partially filling porous media and polymer melts in nanoscopic pores. Diffusion in partially filled porous media was also studied with the aid of an NMR diffusometry technique. It is shown that hydrodynamic flow influences the spin-lattice relaxation rate of water confined in mesoscopic porous media under certain conditions. The effect is predicted by an analytical theory and Monte Carlo simulations, and confirmed experimentally by field-cycling NMR relaxometry. Field-cycling NMR relaxometry has been applied to polar and non polar adsorbates in partially filled silica porous glasses. The dependence of the spin-lattice relaxation rate on the filling degree shows that limits for slow and fast exchange between different phases can be distinguished and identified depending on the pore size and polarity of the solvents. Diffusion in the same unsaturated systems was studied with the aid of NMR diffusometry technique. The effective diffusion coefficient of solvents with different polarities displays opposite tendencies as a function of the liquid content. A two-phase fast exchange model including Knudsen and ordinary diffusion and different effective tortuosities is presented accounting for these phenomena. In the case of polymer melts confined in narrow artificial tubes of a porous solid matrix with variable diameter (9 to 57 nm), the characteristics of reptation were experimentally verified using proton field cycling NMR relaxometry technique. This observation is independent of the molecular mass and pore size. In bulk, the same polymer melts show either Rouse or renormalized Rouse dynamics, depending on the molecular mass. The polymers under confinement show features specific for reptation even with a pore diameter 15 times larger than the Flory radius while bulk melts of the same polymers do not.dc.description.abstract
Languageendc.language.iso
PublisherUniversität Ulmdc.publisher
LicenseStandard (Fassung vom 03.05.2003)dc.rights
Link to license texthttps://oparu.uni-ulm.de/xmlui/license_v1dc.rights.uri
KeywordHydrodynamic dispersiondc.subject
KeywordPolymer dynamicsdc.subject
KeywordPore confinementdc.subject
KeywordSilica glassesdc.subject
KeywordVapor phasedc.subject
Dewey Decimal GroupDDC 530 / Physicsdc.subject.ddc
LCSHDiffusiondc.subject.lcsh
LCSHNuclear magnetic resonancedc.subject.lcsh
LCSHPorous materialsdc.subject.lcsh
LCSHRelaxation spectroscopydc.subject.lcsh
TitleMolecular dynamics in porous media studied by Nuclear Magnetic Resonance techniquesdc.title
Resource typeDissertationdc.type
DOIhttp://dx.doi.org/10.18725/OPARU-453dc.identifier.doi
URNhttp://nbn-resolving.de/urn:nbn:de:bsz:289-vts-55830dc.identifier.urn
GNDField-cyclingdc.subject.gnd
GNDKernspinrelaxationdc.subject.gnd
GNDReptationdc.subject.gnd
FacultyFakultät für Naturwissenschaftenuulm.affiliationGeneral
Date of activation2006-04-19T15:15:41Zuulm.freischaltungVTS
Peer reviewneinuulm.peerReview
Shelfmark print versionZ: J-H 11.108 ; W: W-H 9.051uulm.shelfmark
DCMI TypeTextuulm.typeDCMI
VTS ID5583uulm.vtsID
CategoryPublikationenuulm.category
Bibliographyuulmuulm.bibliographie


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