Confinement Effects on Glass-Forming Aqueous Dimethyl Sulfoxide Solutions.
Combining broadband dielectric spectroscopy and nuclear magnetic resonance studies, we analyze the reorientation dynamics and the translational diffusion associated with the glassy slowdown of the eutectic aqueous dimethyl sulfoxide solution in nano-sized confinements, explicitly, in silica pores with different diameters and in ficoll and lysozyme matrices at different concentrations. We observe that both rotational and diffusive dynamics are slower and more heterogeneous in the confinements than in the bulk but the degree of these effects depends on the properties of the confinement and differs for the components of the solution. For the hard and the soft matrices, the slowdown and the heterogeneity become more prominent when the size of the confinement is reduced. In addition, the dynamics are more retarded for dimethyl sulfoxide than for water, implying specific guest-host interactions. Moreover, we find that the temperature dependence of the reorientation dynamics and of the translational diffusion differs in severe confinements, indicating a breakdown of the Stokes-Einstein-Debye relation. It is discussed to what extent these confinement effects can be rationalized in the framework of core-shell models, which assume bulk-like and slowed-down motions in central and interfacial confinement regions, respectively.
['Demuth|Dominik|D|0000-0003-4648-4875', 'Reuhl|Melanie|M|', 'Hopfenmüller|Moritz|M|', 'Karabas|Nail|N|', 'Schoner|Simon|S|', 'Vogel|Michael|M|0000-0003-2706-3522']
D058266:Dielectric Spectroscopy D004058:Diffusion D004121:Dimethyl Sulfoxide D005362:Ficoll D005898:Glass D057446:Hydrodynamics D009682:Magnetic Resonance Spectroscopy D015233:Models, Statistical D056004:Molecular Dynamics Simulation D009113:Muramidase D012822:Silicon Dioxide D012997:Solvents D013696:Temperature D014867:Water
confinement broadband dielectric spectroscopy nuclear magnetic resonance aqueous solutions glass transition molecular dynamics