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Binary fluids in mesoporous materials: Phase separation studied by NMR relaxation and diffusion
Siegfried Stapf1, Niklas Siebert1, Timo Spalek1
1Technische Physik II/Polymerphysik, Technische Universität Ilmenau, D-98684, Ilmenau, Germany.
Magnetic Resonance Letters
|September 8, 2025
Summary
This study investigates liquid-surface interactions in porous glass using relaxation and diffusion measurements. Findings reveal preferential adsorption and phase separation in binary liquid systems within nanopores.
Area of Science:
- Materials Science
- Physical Chemistry
- Surface Science
Background:
- Porous glass (Vycor) with controlled pore sizes (approx. 4 nm) was used to study liquid behavior.
- Understanding liquid-surface interactions is crucial for various applications, including catalysis and separations.
Purpose of the Study:
- To investigate liquid-surface interactions in nanoporous materials using relaxation and diffusion measurements.
- To analyze the influence of pore confinement on molecular dynamics and interactions.
Main Methods:
- Nuclear Magnetic Resonance (NMR) relaxation measurements (T1 and T2) were performed on single and binary liquid systems.
- Diffusion measurements were used to determine apparent tortuosity and assess phase separation.
Main Results:
- Longitudinal relaxation time (T1) dispersion was observed for both polar and non-polar liquids, indicating liquid-surface interactions.
- Transverse relaxation time (T2) changes probed the strength of molecular interactions.
- Differences in relaxation dispersion between single and binary systems provided evidence for preferential adsorption and phase separation.
- Intermolecular relaxation mechanisms were suggested for 1H nuclei.
Conclusions:
- Liquid-surface interactions in nanoporous glass are significant, affecting molecular dynamics.
- Preferential adsorption and phase separation occur in binary liquid mixtures within the pores.
- NMR relaxation and diffusion measurements are effective tools for characterizing complex fluid behavior in porous media.
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