Berlin 2015 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 32: P4: Computational Physics of Soft Matter

CPP 32.4: Poster

Tuesday, March 17, 2015, 14:00–16:00, Poster B

Structure and Dynamics of a Mixture of Ethylene Glycol and Water in Confinement — •Rebecca Schmitz and Michael Vogel — Institut für Festkörperphysik, TU Darmstadt, Germany

In numerous biological processes and technical applications the motion of molecules in aqueous solutions is restricted by boundary surfaces. Therefore it is crucial to understand the impact of nanoscale confinement on structure and dynamics of liquids. We study the behavior of a mixture of ethylene glycol and water in cylindrical silica nanopores using molecular dynamics simulations. The usage of both amorphous and crystalline nanopores provides us with further insights into the role played by the structure of the confinement. For all systems we find a considerable slowdown of the structural relaxation approaching the wall while the dynamics of the inner layer is comparable to bulk behavior. But while the dynamics of the liquid is similar in all pores, its structure depends strongly on the exact configuration of the confinement. The investigation of the liquid's density profile indicates a local microphase separation induced by the confinement as one molecular species preferentially attaches to the wall. Though reported by various groups, the physics behind this effect is not very clear yet and there is no agreement on whether water or alcohol constitutes the outer layer [1,2]. As we find a very different structure of the liquid in the amorphous and the crystalline pore, our simulation study reveals further information on the influence of various parameters of the confinement.

[1] Guo et al.; J. Phys. Chem. B 118, 34 (2014)

[2] Elamin et al.; PCCP 15, 42 (2013)