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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 33: Glasses and Glass Transition (joint session DY/CPP)

CPP 33.6: Vortrag

Montag, 16. März 2020, 16:30–16:45, ZEU 118

Broadband Dielectric and Nuclear Magnetic Resonance Spectroscopy Studies on Dynamics of Ethylene Glycol in Soft and Hard Confinement — •Melanie Reuhl, Max Weigler, and Michael Vogel — Institut für Physik kondensierter Materie, Technische Universität Darmstadt

As hydrogen-bond networks are often restricted or confined in nature and technology, we investigate the influence of the type of confinement on hydrogen-bonded systems. Using nuclear magnetic resonance (NMR) and broadband dielectric spectroscopy (BDS), we analyse the dynamics of ethylene glycol (EG) in nanoporous silica, elastin and Ficoll matrices over broad temperature ranges. For all investigated systems, BDS and NMR results consistently indicate a slowdown and an enhanced heterogeneity of dynamics due to confinement. For EG in silica pores, calorimetric studies reveal partial freezing at temperatures below the bulk freezing point, indicating substantial freezing point suppression. We study changes in the dynamical behaviour when the confined liquid evolves into coexisting liquid and solid phases upon cooling. The dynamical behaviour of both EG phases in silica confinement is independent of pore size for diameters below 6 nm. In the studied soft confinements, fractional freezing does not occur. Still, two dynamically distinguishable EG species occur, which can be assigned to free EG and interfacial EG at elastin/sugar surfaces.