Analysis by mass spectrometry of the hydrolysis/condensation reaction of a trialkoxysilane in various dental monomer solutions§

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  • This article is a US Government work and, as such, is in the public domain in the United States of America.

  • This article is an official contribution of the National Institute of Standards and Technology (NIST) and is not subject to copyright in the United States. Opinions expressed in this report are those of the authors and do not necessarily reflect the views or policies of the Food and Drug Administration.

  • §

    Certain equipment, instruments or materials are identified in this article to adequately specify the experimental details. Such identification does not imply recommendation by the NIST nor does it imply the materials are necessarily the best available for the purpose.

Abstract

3-Methacryloxypropyltrimethoxysilane (MPTMS) was converted to silsesquioxane oligomers by hydrolysis/condensation in three dental monomer solutions. The molecular mass distribution and molecular structures of these oligomers was studied by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Each dental monomer imparted distinct characteristics on the oligomeric silsesquioxane produced. Ethoxylated bisphenol A dimethacrylate (EBPADMA) produced low-mass oligomer silsesquioxanes that showed complete hydrolysis and a very high degree of intramolecular condensation (i.e., there were no methoxy and few silanol groups remaining on the oligomers). 1,6-Bis(methacryloxy-2-ethoxycarbonylamino) 2,4,4-trimethylhexane also produced fully hydrolyzed oligomeric silsesquioxanes but with twice the average molecular mass as the EBPADMA. Finally, triethylene glycol dimethacrylate produced higher mass oligomeric silsesquioxanes than EBPADMA even though it showed incomplete hydrolysis. The degree of hydrolysis increased with increasing mass, as did the degree of intramolecular condensation. Oligomers with degrees of polymerization below 8 were poorly hydrolyzed and showed little if any intramolecular condensation. Those with degrees of polymerization of 9 or greater were almost completely hydrolyzed with a high level of intramolecular condensation. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1842–1847, 2006

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