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Surface Studies of Porous Materials Using Solid-state NMR and DNP-SENS

Kumari, Bharti (2020):
Surface Studies of Porous Materials Using Solid-state NMR and DNP-SENS.
Darmstadt, Technische Universität Darmstadt,
DOI: 10.25534/tuprints-00011470,
[Ph.D. Thesis]

Abstract

In this thesis, solid-state NMR techniques partially combined with DNP were extensively used to study surface interactions and the surface functionalization of various porous materials. Three types of materials are discussed in the thesis: (i) mesoporous silica SBA-15, (ii) etched ion-track polycarbonate membranes and (iii) complex cellulose paper substrates.

For mesoporous silica, the detailed investigation of interactions of water and octanol-1 molecules with the pore surface of silica SBA-15 is presented. For this, conventional room temperature 1D and 2D solid-state NMR techniques were utilized. Local interactions between surface and guest molecules (octanol-1 and water) were studied by 1H-29Si FSLG CPMAS HETCOR experiments.

While working on FSLG CPMAS HETCOR experiments, a challenging referencing problem on the indirect proton dimension was observed. Thus, a new referencing approach was developed using the 2D 1H-1H MAS FSLG pulse sequence, which allows the exact referencing of the indirect dimension of the FSLG CPMAS HETCOR.

Furthermore, complex materials were also examined, eg., etched ion-track polycarbonate foils and cellulose paper substrates. Since these materials contain low surface areas, it was necessary to use DNP technique. The characterization of the pore surface of silica-coated ion etched PC membrane was investigated by DNP-SEN technique.

Furthermore, functionalized paper substrates were investigated with DNP-SENS and various kinds of radical matrices were examined in order to obtain a correlation between the polarization matrix and achievable signal enhancement in the spectra.

Item Type: Ph.D. Thesis
Erschienen: 2020
Creators: Kumari, Bharti
Title: Surface Studies of Porous Materials Using Solid-state NMR and DNP-SENS
Language: English
Abstract:

In this thesis, solid-state NMR techniques partially combined with DNP were extensively used to study surface interactions and the surface functionalization of various porous materials. Three types of materials are discussed in the thesis: (i) mesoporous silica SBA-15, (ii) etched ion-track polycarbonate membranes and (iii) complex cellulose paper substrates.

For mesoporous silica, the detailed investigation of interactions of water and octanol-1 molecules with the pore surface of silica SBA-15 is presented. For this, conventional room temperature 1D and 2D solid-state NMR techniques were utilized. Local interactions between surface and guest molecules (octanol-1 and water) were studied by 1H-29Si FSLG CPMAS HETCOR experiments.

While working on FSLG CPMAS HETCOR experiments, a challenging referencing problem on the indirect proton dimension was observed. Thus, a new referencing approach was developed using the 2D 1H-1H MAS FSLG pulse sequence, which allows the exact referencing of the indirect dimension of the FSLG CPMAS HETCOR.

Furthermore, complex materials were also examined, eg., etched ion-track polycarbonate foils and cellulose paper substrates. Since these materials contain low surface areas, it was necessary to use DNP technique. The characterization of the pore surface of silica-coated ion etched PC membrane was investigated by DNP-SEN technique.

Furthermore, functionalized paper substrates were investigated with DNP-SENS and various kinds of radical matrices were examined in order to obtain a correlation between the polarization matrix and achievable signal enhancement in the spectra.

Place of Publication: Darmstadt
Divisions: 07 Department of Chemistry
07 Department of Chemistry > Physical Chemistry
Date Deposited: 05 Apr 2020 19:56
DOI: 10.25534/tuprints-00011470
Official URL: https://tuprints.ulb.tu-darmstadt.de/11470
URN: urn:nbn:de:tuda-tuprints-114707
Referees: Buntkowsky, Prof. Dr. Gerd ; Gutmann, PD. Dr. Torsten
Refereed / Verteidigung / mdl. Prüfung: 25 November 2019
Alternative Abstract:
Alternative abstract Language

In dieser Arbeit wurden Festkörper-NMR-Techniken, die teilweise mit DNP kombiniert wurden, genutzt, um Oberflächenwechselwirkungen mit Gastmolekülen sowie die Oberflächenfunktionalisierung verschiedener poröser Materialien zu untersuchen. Dazu standen drei Arten von Materialien: (i) mesoporöses Siliciumdioxid SBA-15, (ii) ionengeätzte Polycarbonatmembranen und (iii) komplexe Cellulosepapiersubstrate, zur Verfügung. Für mesoporöses Siliciumdioxid wird die detaillierte Untersuchung der Wechselwirkungen von Wasser und Octanol-1-Molekülen mit der Porenoberfläche von Siliciumdioxid SBA-15 vorgestellt. Hierzu wurden 1D- und 2D-Festkörper-NMR-Techniken bei Raumtemperatur verwendet. Die lokalen Wechselwirkungen zwischen Oberfläche und Gastmolekülen (Octanol-1 und Wasser) wurden mittels 1H-29Si FSLG-CPMAS-HETCOR-Experimenten untersucht. Während der Arbeit an FSLG-CPMAS-HETCOR-Experimenten ergab sich ein Referenzierungsproblem für die indirekte Protonendimension. Zur Lösung dieses Problems wurde eine neue Referenzierungstechnik unter Verwendung einer 2D 1H-1H MAS FSLG-Pulssequenz entwickelt, welche eine eindeutige Referenzierung der indirekten Dimension der FSLG-HETCOR-Spektren ermöglicht. Desweiteren wurden auch komplexe Materialien untersucht, z. B. geätzte Ionenkanälen enthaltende Polycarbonatfolien sowie Cellulosepapiersubstrate. Da diese Materialien eine geringe spezifische Oberfläche aufweisen, war es erforderlich DNP-Techniken zu verwenden. Die Charakterisierung der Porenoberfläche einer Siliciumdioxid beschichteten, ionengeätzten PC-Membran erfolgte entsprechend mittels der DNP-SENS-Technik. Desweiteren wurden funktionalisierte Papiersubstrate mit DNP-SENS-Techniken und unterschiedlichen Arten von Radikalmatrizen untersucht, um einen Zusammenhang zwischen Polarisationsmatrix und erreichbarer Signalverstärkung in den Spektren zu bestimmen.

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