UV-MALDI-TOF and ESI-TOF mass spectrometry characterization of silsesquioxanes obtained by the hydrolytic condensation of (3-glycidoxypropyl)-trimethoxysilane in an epoxidized solvent

摘要

Full Paper: Silsesquioxanes obtained by the hyrolytic condensation of (3-glycidoxypropyl)trimethoxysilane (GPMS) in diglycidyl ether of bisphenol A (DGEBA) were characterized by electrospray ionization time-of- flight mass spectrometry (ESI-TOF MS) and matrix assisted ultraviolet laser desorption/ionization, ti flight mass spectrometry (UV-MALDI-TOF MS) employing two different matrices and both positive negative ion modes. A bimodal distribution of in the 1300-6400 m/z range, was observed in mass spectra. This distribution accounted gomers formed in two successive generations but I include a cluster of higher molar-mass species pre SEC chromatograms. Most of the peaks present and MALDI mass spectra could be described by eric formula T-n(OCH3)(m) with in = 0, 2, and 4 for n = even, m = 1, 3, 5 for n = odd, and T = RSiO(3n-m)/2n corresponds to completely condensed polyhedra (incompletely hydrolyzed polyhedra (m = 1 to 3). ar precursors (in = 4). Predominant species in the first contained 10 to 14 Si atoms whereas those in: the cluster had 18 to 23 Si atoms. Small amounts of following species: T-8(OH)(OCH3), T-9(OH), T-10(OH)(OCH3) and T-11(OH) could be identified in MALDI MS 9H-pyrido3,4-bindole (nor-harmane) as matrix ! negative ion mode. It was inferred that some, of the species had a relevant participation in the generation, second cluster of higher molar masses. The stability of the silsequioxane solution in DGEBA was the result of the very small concentration of free SiOH groups available small concentration of free SiOH groups available for further condensation. References: 19