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Molecular Orbital Modeling of Water Adsorption on a Tetrasiloxane Ring

Published online by Cambridge University Press:  28 February 2011

J. K. West  and
S. Wallace
J. K. West
Affiliation:
Advanced Materials Research Center, University of Florida, One Progress Blvd. #14, Alachua, Fl 32615.
S. Wallace
Affiliation:
Advanced Materials Research Center, University of Florida, One Progress Blvd. #14, Alachua, Fl 32615.
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Abstract

A water molecule hydrogen bonded to a surface SiOH group produces an IR vibrational transmission peak (ν3) at 2.82 μm. Water was adsorbed into the pores of a metal alkoxide derived silica gel monolith, and the increase in the wavelength of the first vibrational overtone (2ν3) of this peak was measured as a function of the adsorbed water content W (g H2O/g SiO2). The peak shifted from 1.390 to 1.420 μm as W increased by 0.14 g/g. Intermediate Neglect of Differential Overlap (INDO) Molecular Orbital (MO) theory was used to model this process. The effect of a H2O molecule, hydrogen bonded to a hydroxylated tetrasiloxane ring, on the structure of the ring and the water molecule was investigated. The bond length of the O-H group H-bonded to the water molecule increased, as expected from the increase in wavelength of the 2ν3 IR peak.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 180: Symposium A – Better Ceramics Through Chemistry IV , 1990 , 255
Copyright
Copyright © Materials Research Society 1990

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References

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