Study of the acid hydrolysis of (3-methacryloxypropyl)trimethoxysilane by capillary electrophoresis–ion-trap mass spectrometry

The sol–gel method is a widely used technique for the synthesis of various functional coating films. Alkoxysilanes such as (3-methacryloxypropyl)trimethoxysilane (MEMO) are largely used as precursors for inorganic–organic hybrid sol–gel materials. Indeed, these compounds can form complex network, through hydrolysis and condensation reactions. The latter have to be perfectly controlled to obtain the required properties. In such a context, we have studied the potentialities of capillary electrophoresis–ion-trap mass spectrometry (CE–MS) coupling to resolve both separation and characterization of the synthesized compounds as a function of the hydrolysis time. The study of acid hydrolysis of MEMO was carried out as an example. After optimization of the running electrolyte in capillary zone electrophoresis (CZE) with UV detection, we characterized the synthesized compounds in CE–MS by using positive detection mode. The obtained resolution in CZE–UV was not entirely satisfactory because of the very closed charge/mass ratio of formed solute but also because of the interaction between the solutes and the capillary walls. Nevertheless, several oligomers were characterized in CE–MS. The absence of detection with regard to oligomers that possess higher molecular masses than octamer is discussed in this work.