Regensburg 2013 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 8: Poster I: Glasses and Glass Transition (joint session DY/DF/CPP)

DY 8.8: Poster

Montag, 11. März 2013, 17:30–19:30, Poster C

The interplay between inter- and intramolecular dynamics in a series of alkylcitrates — •Wycliffe Kipnusu¹, Wilhelm Kossack¹, Ciprian Iacob¹, Joshua Sangoro², and Friedrich Kremer¹ — ¹Institute of Experimental Physics I, University of Leipzig, Linnestr. 5, 04103 Leipzig, Germany — ²Chemical Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830-6197, United States.

The inter- and intra-molecular dynamics in a series of glass-forming alkylcitrates is studied by a combination of Broadband Dielectric (BDS), Pulsed Field Gradient Nuclear Magnetic Resonance (PFG NMR), Dynamic Mechanical (DMS), and Fourier-Transform Infrared (FTIR) Spectroscopy. Analyzing the temperature dependencies of specific IR absorption bands in terms of their spectral position and the corresponding oscillator strengths enables one to unravel the intramolecular dynamics of specific molecular moieties and to compare it with the intermolecular dynamics. With decreasing temperature, the IR band positions of carbonyls and H-bonded moieties of citrates, show a red shift with a kink at Tg while other moieties whose dynamics are decoupled from those of the core units, exhibit a blue shift with nominal changes at Tg. The oscillator strength of the ester linkage and H-bonded units show a kink at a temperature where structural and faster secondary relaxations merge. By that, a wealth of novel information is obtained proving the fundamental importance of intramolecular mobility in the process of glass formation, beyond coarse-grained descriptions. Reference:Papadopoulos P. etal. Softmatter 2012 In press.