Characterization of low molecular weight components of [(ViMe 2 SiO 1/2 ) x (PhSiO 3/2 ) y (SiO 4/2 ) z ], [(ViMe 2 SiO 1/2 ) x (SiO 4/2 ) y ], and [(SiO 4/2 ) x (HO 1/2 ) y ( t BuO 1/2 ) z ] silsesquioxanes by electrospray ionization fourier transform mass spectrometry (ESI-FTMS)
2005; American Chemical Society; Volume: 16; Issue: 4 Linguagem: Inglês
10.1016/j.jasms.2005.01.001
ISSN1879-1123
AutoresHuiping Chen, Duane R. Bujalski, Kai Su,
Tópico(s)Diamond and Carbon-based Materials Research
ResumoThis 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 [(ViMe2SiO1/2)x(PhSiO3/2)y(SiO4/2)z] (MTQ), [(ViMe2SiO1/2)x(SiO4/2)y] (MQ), and [(SiO4/2)x(HO1/2)y(tBuO1/2)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 (TnQmMn+2m+2), and monocyclic (TnQmMn+2m) 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 (QmM2m−6 and QmM2m−8), 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.
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