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Methyl group dynamics in a confined glass

A. J. Moreno·J. Colmenero·A. Alegría·C. Alba-Simionesco·G. Dosseh·D. Morineau·B. Frick
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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 Amstrong as a lower limit of the interaction range, beyond the typical nearest-neighbour distance between centers-of-mass (4.7 Amstrong).

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A. J. Moreno, J. Colmenero, A. Alegría, C. Alba-Simionesco, G. Dosseh, D. Morineau, B. Frick. 2003-02-04. Methyl group dynamics in a confined glass. https://arxiv.org/abs/cond-mat/0212480

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