Effect of adding nanometre-sized heterogeneities on the structural dynamics and the excess wing of a molecular glass former

S Gupta; J K H Fischer; P Lunkenheimer; A Loidl; E Novak; N Jalarvo; M Ohl

doi:10.1038/srep35034

Effect of adding nanometre-sized heterogeneities on the structural dynamics and the excess wing of a molecular glass former

Sci Rep. 2016 Oct 11:6:35034. doi: 10.1038/srep35034.

Authors

S Gupta^{1

2

3}, J K H Fischer⁴, P Lunkenheimer⁴, A Loidl⁴, E Novak⁵, N Jalarvo^{1

6}, M Ohl^{1

2}

Affiliations

¹ Juelich Centre for Neutron science (JCNS) outstation at SNS, POB 2008, 1 Bethel Valley Road, TN 37831, Oak Ridge, USA.
² Biology and Soft Matter Division, Neutron Sciences Directorate, Oak Ridge National Laboratory (ORNL), POB 2008, 1 Bethel Valley Road, TN 37831, Oak Ridge, USA.
³ Department of Chemistry and Macromolecular Studies Group, Louisiana State University, Baton Rouge, LA 70803, USA.
⁴ Experimental Physics V, Center for Electronic Correlations and Magnetism, University of Augsburg, 86135 Augsburg, Germany.
⁵ Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA.
⁶ Chemical and Engineering Materials Division, Oak Ridge National Laboratory (ORNL), PO BOX 2008 MS6473, TN 37831, Oak Ridge, USA.

Abstract

We present the relaxation dynamics of glass-forming glycerol mixed with 1.1 nm sized polyhedral oligomeric silsesquioxane (POSS) molecules using dielectric spectroscopy (DS) and two different neutron scattering (NS) techniques. Both, the reorientational dynamics as measured by DS and the density fluctuations detected by NS reveal a broadening of the α relaxation when POSS molecules are added. Moreover, we find a significant slowing down of the α-relaxation time. These effects are in accord with the heterogeneity scenario considered for the dynamics of glasses and supercooled liquids. The addition of POSS also affects the excess wing in glycerol arising from a secondary relaxation process, which seems to exhibit a dramatic increase in relative strength compared to the α relaxation.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.