Variation of the surface charge of silica particles by functionalised self-assembled monolayers

In this study the synthesis of functionalized self-assembled monolayers (SAMs) with SH, SO3H, NH2 and CN functionality onto silica particles and their properties has been studied and characterized by infrared spectroscopy, time-of-flight secondary ion mass spectrometry (ToF-SIMS) and measurement of the ζ potential of the resulting powder. The infrared and ToF-SIMS measurements of the samples clearly show the presence of CH2 goups and the various functionalized head groups of the SAMs, indicating a successful deposition of the SAMs onto the silica particles. The measurements of the ζ potential of the samples show clear variations of their ζ potential depending on the type of SAM compared to the ζ potential of the pure silica powder used in this study. Even positive ζ potential could be measured for silica powder coated with NH2 and CN SAM.