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Cooling Rate Dependent Ellipsometry Measurements to Determine the Dynamics of Thin Glassy Films
Published on: January 27, 2016
Methyl group dynamics in a confined glass
A J Moreno1, J Colmenero, A Alegría
1Laboratoire des Verres, CNRS-UMR 5587, Université de Montpellier II, Bâtiment 13, 34095 Montpellier, France. moreno@ldv.univ-montp2.fr
Abstract:
We present a neutron scattering investigation on methyl group dynamics in glassy toluene confined in mesoporous silicates of different pore sizes. The experimental results have been analysed in terms of a barrier distribution model, such a distribution following from the structural disorder in the glassy state. Confinement results in a strong decreasing of the average rotational barrier in comparison to the bulk state. We have roughly separated the distribution for the confined state in a bulk-like and a surface-like contribution, corresponding to rotors at a distance from the pore wall respectively larger and smaller than the spatial range of the interactions which contribute to the rotational potential for the methyl groups. We have estimated a distance of 7 A as a lower limit of the interaction range, beyond the typical nearest-neighbour distance between centers-of-mass (4.7 A).
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