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Polymerization of tetramethylcyclotetrasiloxane monomer by ion-exchanged montmorillonite catalysts

Published online by Cambridge University Press:  09 July 2018

S. Nishihama ,
H. Yamada  and
H. Nakazawa
S. Nishihama
Affiliation:
Shiseido Research Center, 1050 Nippa-cho, Kohoku-ku, Yokohama-shi 223 Japan
H. Yamada
Affiliation:
National Institute for Research in Inorganic Materials, 1-1 Namila, Tsulcuba-shi, Ibaraki, 305 Japan
H. Nakazawa
Affiliation:
National Institute for Research in Inorganic Materials, 1-1 Namila, Tsulcuba-shi, Ibaraki, 305 Japan
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Abstract

Montmorillonites ion-exchanged with Li+, Na+, K+ Ca2+, Mg2+ and Ni2+ and acidic clay were used as catalysts for the polymerization of a cyclic siloxane monomer, 2,4,6,8- tetramethylcyclotetrasiloxane. Montmorillonites with Ni2+ and Mg2+ in the interlayer, and acidic clay exhibit a greater ability for siloxane polymerization in both yield and mean molecular weight of products than those containing Li+, Na+ and K+. The difference in catalytic ability of the ionexchanged montmorillonites is caused by the number of Brmasted acid sites due to the polarization of H2O. This was confirmed experimentally by FTIR analysis of pyridine-treated samples. Therefore, it may be possible to design a catalyst for controlling siloxane polymerization (i.e. mean molecular weight of product) by changing the number of Bronsted acid sites through exchange of the interlayer cations of montmorillonites.

Type
Research Article
Information
Clay Minerals , Volume 32 , Issue 4 , December 1997 , pp. 645 - 651
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1997

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