Hierarchical micro-to-macroporous silica nanoparticles obtained by their grafting with hyper-crosslinked resin

In this work, mesoporous silica nanoparticles (MSN) hybridized with an organosilane are grafted with hyper-crosslinked poly(vinylbenzyl chloride) (PVBC), which is anchored into the mesopores and onto the external surface of MSN. The obtained nanoparticles are characterized by a MSN-templated hierarchical porosity composed of micropores, mesopores and macropores originated from the hyper-crosslinking of the PVBC phase, with a microporous fraction reaching up to 28% of the total pore volume. Tested for the adsorption of a model dye (Rhodamine 6G, Rh6G), these nanoparticles result much more efficient in Rh6G adsorption with respect to plain MSN, showing a Rh6G uptake of about 125 mg/g in highly concentrated solutions (1000 mg/L) and quite complete removal (about 98%) of the dye in more diluted conditions (30 mg/L) with comparable efficiency in repeated adsorption cycles. Overall results demonstrate the key role of the hierarchical porosity of the hyper-crosslinked PVBC-grafted MSN to tailor their adsorption properties.