One-Step Synthesis of Polyhedral Silsesquioxanes Bearing Bulky Substituents: UV-MALDI-TOF and ESI-TOF Mass Spectrometry Characterization of Reaction Products
Year: 2001
Type: article
Abstract: The NaOH-catalyzed hydrolytic condensation of the reaction product between N -(β-aminoethyl)-γ-aminopropyltrimethoxysilane and phenyl glycidyl ether (PGE) was followed by matrix-assisted ultraviolet laser desorption/ionization time-of-flight mass spectrometry (UV-MALDI-TOF MS) and electrospray ionization time-of-flight mass spectrometry (ESI-TOF MS). After 24 h at 50 °C, main condensation products were a mixture of perfect and imperfect polyhedra: T 8, T 9 (OH), and T 10, with traces of T 7 (OH) and T 11 (OH). Every one of these products was composed of a series of peaks in the mass spectra, accounting for the incomplete reaction of PGE with the aminosilane (e.g., T 8 showed the presence of the species containing 24 PGE units arising from the complete reaction of the initial silane, as well as species containing 23, 22, and 21 PGE units). A thermal treatment to 150 °C led to the appearance of extra peaks corresponding to intramolecular dehydration products. Peaks corresponding to the loss of one water molecule from T 9 (OH) and T 7 (OH) were present and could be ascribed to the reaction between SiOH and a secondary OH group. Dehydration products from T 8 and T 10 were observed, as well as species arising from the loss of two water molecules from T 9 (OH) and T 7 (OH). A plausible explanation for the presence of these peaks is the rupture of a Si−O−Si bond in the presence of NaOH, followed by condensation of the resulting fragments with secondary OH groups.
Source: Macromolecules
DOI: 10.1021/ma001711k
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
Award: G7378882120
OpenAlex ID: W1983289775