Glassy dynamics in nanoconfinement as revealed by 31p NMR.
We investigated the glass former m-tricresyl-phosphate confined in different nanoporous silica matrices with defined pore radii from 2-150 nm. While applying different 31P NMR techniques, we were able to detect the extremely stretched correlation functions extending over 7-8 decades in time and reflecting strong dynamic heterogeneities. The experimental results were explained by a topological model for which the broad distribution of correlation times G(ln tau) becomes inhomogeneous in space; that is, the "local" dynamics given by a correlation time tau(r) depend on the distance from the pore center. As tau(r) changes with temperature, we were able to reintroduce the idea of a dynamic correlation length.
Gradmann
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S
Medick
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Rössler
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EA