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Effects of Surfaces on the Melting/Freezing Behavior of Fluids in Derivatized- and Nude-Porous Silica

Published online by Cambridge University Press:  15 February 2011

V. K. Malhotra ,
R. Mu  and
A. Natarajan
V. K. Malhotra
Affiliation:
Department of Physics, Southern Illinois University at Carbondale, Carbondale, Illinois 62901-4401
R. Mu
Affiliation:
Fisk Center, Fisk University, Nashville, TN 37208
A. Natarajan
Affiliation:
Department of Physics, Southern Illinois University at Carbondale, Carbondale, Illinois 62901-4401
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Abstract

Comparative differential scanning calorimetry (DSC) measurements were made at 200 K < T < 310 K on geometrically restricted cyclohexane and n-decane in nude-, trimethyl derivatized-, and hexyl derivatized-porous (Rp = 4 nm) silica with a view to determine how the surface structure of the confining media affects the thermodynamic behavior of the restricted fluid. Our results suggest that, irrespective of the fact that both trimethyl derivatized- and hexyl derivatized-silica have methyl terminal groups, the freezing or melting transition of cyclohexane is much more depressed in trimethyl derivatized-silica than in hexyl derivatized- or nude-silica. This is not the case for n-decane where the depression in the melting transition is consistent with the fact that the effective pore radius of the hexyl derivatized-silica is smaller than the trimethyl derivatized- or nude-silica.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 290: Symposium N – Dynamics in Small Confining Systems , 1992 , 121
Copyright
Copyright © Materials Research Society 1993

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