Berlin 2018 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 7: Biomaterials and Biopolymers (joint session BP/CPP)

CPP 7.2: Vortrag

Montag, 12. März 2018, 09:45–10:00, H 1058

Ion and Molecule Transport Bulk and in Nanopores - a NMR study — •Sarah Schneider and Michael Vogel — TU Darmstadt Institut fuer Festkoerperphysik, Darmstadt, Germany

We analyze ion and molecule transport in aqueous salt solutions confined to nanopores as part of a project that aims to develop a new generation of nanosensors by combining biological and synthetic nanopores. While being highly selective and sensitive, biological ion channels lack the robustness for technological applications. Contrarily silica pores are well-proven in industrial and clinical environments, but possess inferior capabilities, e.g. no selectivity. A hybrid system would combine the favorable properties of both fields.

To optimize such pores, it is of strong interest to understand the influence of the confinement on the T-dependent ion and molecule transport inside. We vary the pore parameters systematically and study their effects on the dynamics by NMR. Using ¹H and ²H NMR we can selectively investigate water dynamics whereas ⁷Li and ²³Na NMR analyze the local and long-range dynamics of ionic species. Analyzing the local ion and water dynamics reveals a slowdown with increasing salt concentration, which may differ in bulk and confinement due to altered prospensity for crystallization. At a given concentration there is a slowdown in confinement with more heterogenious dynamics. Both can be explained by a slower layer at the pore walls and bulk-like dynamics in the pore center. Field-gradient NMR is applied to measure self-diffusion. The extent of the effect and the relation between short- and long-range dynamics depend on the confinement properties.