Effect of pH on the final connectivity distribution of the silicon atoms in the Stöber particles

Kangtaek Lee; Alon McCormick

doi:10.1007/s10971-005-6374-y

Effect of pH on the final connectivity distribution of the silicon atoms in the Stöber particles

Kangtaek Lee, Alon McCormick

Chemical Engineering and Materials Science

Research output: Contribution to journal › Article › peer-review

2 Scopus citations

Abstract

Using ²⁹Si MAS-NMR we investigate the effect of pH on the final connectivity distribution of the silicon atoms in the Stöber particles. Our data suggest that the fraction of the silicon atoms that are ully-connected decreases as the ammonia concentration is increased. This suggests a more negative first shell substitution effect in the precipitated phase (liquid droplet) if condensation reactions are irreversible. A simple model is developed to describe the condensation kinetics in the precipitated phase and the results support the negative first shell substitution effect. These findings challenge the notion of a positive first shell substitution effect in alkaline conditions.

Original language	English (US)
Pages (from-to)	255-260
Number of pages	6
Journal	Journal of Sol-Gel Science and Technology
Volume	33
Issue number	3
DOIs	https://doi.org/10.1007/s10971-005-6374-y
State	Published - Mar 2005

Bibliographical note

Funding Information:
We acknowledge the support of the National Science Foundation (CTS-89 10423) and the Center for Interfacial Engineering at the University of Minnesota. KL acknowledges the support of the Korea Research Foundation (KRF-2003-005-D00001) and Yonsei University Research Fund of 2001.

Keywords

Condensation kinetics
First shell substitution effect
Si MAS-NMR
Stöber particles
pH

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abstract = "Using 29Si MAS-NMR we investigate the effect of pH on the final connectivity distribution of the silicon atoms in the St{\"o}ber particles. Our data suggest that the fraction of the silicon atoms that are ully-connected decreases as the ammonia concentration is increased. This suggests a more negative first shell substitution effect in the precipitated phase (liquid droplet) if condensation reactions are irreversible. A simple model is developed to describe the condensation kinetics in the precipitated phase and the results support the negative first shell substitution effect. These findings challenge the notion of a positive first shell substitution effect in alkaline conditions.",

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AU - McCormick, Alon

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N2 - Using 29Si MAS-NMR we investigate the effect of pH on the final connectivity distribution of the silicon atoms in the Stöber particles. Our data suggest that the fraction of the silicon atoms that are ully-connected decreases as the ammonia concentration is increased. This suggests a more negative first shell substitution effect in the precipitated phase (liquid droplet) if condensation reactions are irreversible. A simple model is developed to describe the condensation kinetics in the precipitated phase and the results support the negative first shell substitution effect. These findings challenge the notion of a positive first shell substitution effect in alkaline conditions.

AB - Using 29Si MAS-NMR we investigate the effect of pH on the final connectivity distribution of the silicon atoms in the Stöber particles. Our data suggest that the fraction of the silicon atoms that are ully-connected decreases as the ammonia concentration is increased. This suggests a more negative first shell substitution effect in the precipitated phase (liquid droplet) if condensation reactions are irreversible. A simple model is developed to describe the condensation kinetics in the precipitated phase and the results support the negative first shell substitution effect. These findings challenge the notion of a positive first shell substitution effect in alkaline conditions.

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Effect of pH on the final connectivity distribution of the silicon atoms in the Stöber particles

Abstract

Bibliographical note

Keywords

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