Dielectric and mechanical relaxation of glass-forming liquids in nanopores

H. Wendt, Ranko Richert

Research output: Chapter in Book/Report/Conference proceedingChapter

1 Scopus citations

Abstract

We have measured the time resolved phosphorescence of different probe molecules in glass-forming solvents under the condition of geometrical confinement in porous glasses. This solvation dynamics technique probes the local dielectric relaxation in the case of a dipolar chromophore in polar liquids. In the absence of dipolar interactions, the observed Stokes shifts reflect the local density or mechanical responses. Therefore, both orientational and translational modes of molecular motions can be measured for liquids imbided in porous silica glasses. The effect of confinement on the relaxations of supercooled liquids is strongly dependent on the surface chemistry and can be rationalized on the basis of the cooperativity concept. As in the bulk case, we find that the relaxations in nano-confined liquids display heterogeneous dynamics. The density relaxation turns out to be more sensitive to the thermal history relative to the orientational features of molecular motion. By selectively positioning the chromophores at the liquid/solid interface, we observe also that the structural relaxation of the liquid in the immediate vicinity of the glass surface is slowed down but not entirely blocked.

Original languageEnglish (US)
Title of host publicationMaterials Research Society Symposium - Proceedings
PublisherMaterials Research Society
Pages15-26
Number of pages12
Volume543
StatePublished - 1999
Externally publishedYes
EventProceedings of the 1998 MRS Fall Meeting - The Symposium 'Advanced Catalytic Materials-1998' - Boston, MA, USA
Duration: Nov 30 1998Dec 3 1998

Other

OtherProceedings of the 1998 MRS Fall Meeting - The Symposium 'Advanced Catalytic Materials-1998'
CityBoston, MA, USA
Period11/30/9812/3/98

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials

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    Wendt, H., & Richert, R. (1999). Dielectric and mechanical relaxation of glass-forming liquids in nanopores. In Materials Research Society Symposium - Proceedings (Vol. 543, pp. 15-26). Materials Research Society.