Characterization of low molecular weight components of [(ViMe₂SiO_1/2)_x(PhSiO_3/2)_y(SiO_4/2)_z], [(ViMe₂SiO_1/2)_x(SiO_4/2)_y], and [(SiO_4/2)_x(HO_1/2)_y(^tBuO_1/2)_z] silsesquioxanes by electrospray ionization fourier transform mass spectrometry (ESI-FTMS)

Abstract

This paper describes the characterization of low molecular weight components of four materials using electrospray ionization Fourier transform mass spectrometry (ESI-FTMS). The materials in the current study are [(ViMe 2 SiO 1/2 ) x (PhSiO 3/2 ) y (SiO 4/2 ) z ] (MTQ), [(ViMe 2 SiO 1/2 ) x (SiO 4/2 ) y ] (MQ), and [(SiO 4/2 ) x (HO 1/2 ) y ( t BuO 1/2 ) z ] (Q) silsesquioxanes. Accurate mass measurements coupled with knowledge of resin chemistry afforded siloxane composition determination that was used to propose specific structures for the oligomers. Branched or linear (T n Q m M nϩ2mϩ2 ), and monocyclic (T n Q m M nϩ2m ) structures are predominant structures for the low molecular weight species in MTQ. For MQ and Q, more condensed structures, such as partially opened cage structures (Q m M 2mϪ6 and Q m M 2mϪ8 ), were identified. The differences between MQ, Q, and MTQ are likely attributed to differences in intrinsic structure and reactivity of T and Q building blocks. The structural information obtained for these oligomeric species will ultimately provide a better understanding of new resin materials and their associated physical properties. (J Am Soc Mass Spectrom 2005, 16, 524 -534)

Synthesis and Properties of MQ Copolymers: Current State of Knowledge

“…A series of MQ copolymers—MTQ, MQ, and Q systems, where T is a difunctional unit determining a presence of linear sections—were synthesized to study the effect of the ratio of M and Q unit quantities on the copolymers structure [63]. ESI-FTMS (Bruker, Billerica, MA, USA) mass spectrometry data showed that the structure of the MQ copolymers was the most condensed (cage-like) compared to the more open structure of the Q systems (ladder-like) and the even more mobile structure of the MTQ copolymers.…”

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

“…1 In this study, we investigated the reaction of MPTMS in three commonly used dental monomers by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), focusing on the in situ formation of oligomeric silsesquioxanes, which are a byproduct of the silanization reaction. [2][3][4][5][6][7][8][9] 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…”