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

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.

Recent Developments of New Components for Dental Adhesives and Composites

“…The analysis of hydrolytic condensation products of 3-methacryloyloxypropyltrimethoxysilane directly in various dental monomer solutions by MALDI-TOF MS was described by Farahani et al. [122] Ethoxylated bisphenol A dimethacrylate (E-Bis-GMA) produced low-mass oligomeric silsesquioxanes that showed complete hydrolysis and condensation. In UDMA fully hydrolysed oligomeric silsesquioxanes were obtained but with twice the average molecular mass as that of E-Bis-GMA.…”

ESI and MALDI mass spectrometry of large POSS oligomers

“…There are to date only a few papers reporting mass spectra of POSS polymers and oligomers [15][16][17][18][19][20][21][22][23]. These studies all investigate systems, and especially synthetic intermediates, in which there are a large number of -OH groups.…”

Characterization of low and intermediate molecular weight hydrogen silsesquioxanes by mass spectrometry

“…FD and DCI were found to be excellent ionization methods for the direct analysis of intermediate molecular weight (1000 -10,000 u) organosilicon polymers including H-resins [9,10]. More recently, other soft ionization techniques such as electrospray ionization (ESI) or matrix assisted laser desorption/ionization (MALDI) have been widely utilized for mass spectrometric analysis of many organofunctional silsesquioxanes [11][12][13][14][15][16][17][18][19][20], however, to the best of our knowledge, nondestructive mass spectrometric results of H-resins using these soft ionization techniques have not previously been published. Herein, we include the FD and DCI mass spectrometric data, which have been presented previously [9,10], and the first MALDI data for a low molecular weight H-resin material.…”