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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 14: Poster: Glasses I (jointly with DY)

CPP 14.7: Poster

Tuesday, March 27, 2012, 18:15–20:15, Poster A

Molecular dynamics of glass forming liquids confined in two dimensional constraint of uni-directional nanopores — •Wycliffe Kipnusu, Ciprian Iacob, Joshua Sangoro, and Friedrich Kremer — Institute of Experimental Physics I, University of Leipzig, Linnestr. 5, 04103 Leipzig, Germany.

Broadband Dielectric Spectroscopy (BDS), Pulse Field Gradient-Nuclear Magnetic Resonance (PFG-NMR) spectroscopy, and Fourier Transform Infrared (FT-IR) spectroscopy are combined to study the molecular dynamics of low molecular weight glass forming liquids (e.g. alkylcitrates) in the bulk state and confined in unidirectional nanopores (diameter: 4, 8, and 10.4 nm, length: 50 microns) prepared by electrochemical etching of highly doped p-type < 100 > silicon and subsequent oxidation. The dynamics of the structural (alpha)relaxation and the diffusion are enhenced by more than 2 orders of magnitude in 4 nm pores at lower temperatures in comparison to the bulk. This is attributed to changes in molecular packing due to geometrical constraint. Apart from a beta- relaxation, a broad process (slower than the alpha- process) assigned to relaxation of interfacial layers is observed for the confined molecules. Silanization of the pores removes this process but does not alter the structural alpha- relaxation.

References:

(1). M. Arndt, etal. Physical review. E, 1996, 54, 5377. (2). F. Kremer Broadband Dielectric Spectroscopy, Springer, Berlin, 2003. (3). R. Prisk, and P. E. Sokol, J. Chem. Phys., 2011, 134, 114506