Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Polymeric Silsesquioxanes: Degree-of-Intramolecular-Condensation Measured by Mass Spectrometry

Published

Author(s)

William E. Wallace, Charles M. Guttman, Joseph M. Antonucci

Abstract

The degree-of-condensation, defined as the number of residual silanol (SiOH) groups per oligomer, for a variety of silsesquioxane polymers was measured by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Condensation of SiOH groups out of the silsesquioxane molecule leads to the formation of intramolecular Si-O-Si bridges accompanied by the loss of water. This elimination reaction is easily identified via high resolution time-of-flight mass spectrometry. Various polymeric silsesquioxanes were prepared from the corresponding trialkoxysilanes by hydrolysis-condensation reactions at moderate temperatures (25 C to 65 C) in aqueous acetone with catalytic amounts of formic acid. A decyl-silsesquioxane was found to have the highest degree on condensation with lower degrees found in n-propyl- and in 3-methacryloxypropyl- silsesquioxanes. A propyl silsesquioxane synthesized without a catalyst was found to have the lowest degree-of-condensation of all as well as the lowest overall molecular weight. In all cases the number of intramolecular Si-O-Si bridges per oligomer was found to be a linear function of the number of repeat units in the oligomer. This linear relationship is discussed in light of theories of condensation polymerization.
Citation
Polymer
Volume
41
Issue
No. 6

Keywords

mass spectrometry, polymerization, silsesquioxanes

Citation

Wallace, W. , Guttman, C. and Antonucci, J. (2000), Polymeric Silsesquioxanes: Degree-of-Intramolecular-Condensation Measured by Mass Spectrometry, Polymer, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=851556 (Accessed December 4, 2024)

Issues

If you have any questions about this publication or are having problems accessing it, please contact reflib@nist.gov.

Created February 29, 2000, Updated October 12, 2021