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Prolonged Chaotic Oscillations During the Gel/Xerogel Transition in Silicon Tetramethoxide Polymerization as Detected by Pyrene Excimerization.

Published online by Cambridge University Press:  28 February 2011

Vered R. Kaufman  and
David Avnir
Vered R. Kaufman
Affiliation:
Department of Organic Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
David Avnir
Affiliation:
Department of Organic Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
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Abstract

When the polymerization of Si(OCH3)4 is carried out in the presence of surface active agents, prolonged oscillations (over 1000 hrs) at the gel/xerogel transition are observed. The oscillations are of large amplitude, they are slow (several hrs/period), and they exhibit a chaotic behaviour. The probe by which these oscillations are observed is emission from excited state monomeric and excimeric pyrene. It is suggested tentatively that the driving forces for this oscillation are the structural relaxation of the secondary polymeric gel structure and the dispersion of adsorbed pyrene to thermodynamically favored adsorption sites. Relevant models could be those of oscillatory sol/gel phase transitions and of oscillatory polymerization reactions. We are unaware of previous observations of oscillations in sol/gel systems.

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Articles
Information
MRS Online Proceedings Library (OPL) , Volume 73: Symposium H – Better Ceramics Through Chemistry II , 1986 , 145
Copyright
Copyright © Materials Research Society 1986

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