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

• Main Author: Kumari, Bharti
• Format: Others
• Language: en
• Published: 2020
• Online Access: https://tuprints.ulb.tu-darmstadt.de/11470/1/Bharti%20Kumari%20Ph.D.%20Thesis.pdf; Kumari, Bharti <http://tuprints.ulb.tu-darmstadt.de/view/person/Kumari=3ABharti=3A=3A.html> (2020): Surface Studies of Porous Materials Using Solid-state NMR and DNP-SENS.Darmstadt, Technische Universität Darmstadt, DOI: 10.25534/tuprints-00011470 <https://doi.org/10.25534/tuprints-00011470>, [Ph.D. Thesis]

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.