Polyamine-decorated mesocellular silica foam nanocomposites: Effect of the reaction parameters on the grafted polymer content and silica mesostructure

Polyvinylamine-coated mesocellular silica foam (MCF) was synthesized by grafting poly(n-vinylformamide) (PNVF) followed by the acid hydrolysis of the formamide groups with hydrochloric acid (HCl) and subsequent neutralization with sodium hydroxide (NaOH). In order to graft PNVF, MCF silica was previously functionalized with the coupling agent vinyltrimehtoxysilane (VTMS). The PNVF content in the hybrid material was tailored by varying some reaction parameters such as monomer concentration, reaction time, and temperature. The grafted polymer content was determined by thermogravimetric analysis (TGA) and ranged from 27% to 50%. Additionally, small-angle X-ray scattering (SAXS), infrared spectroscopy (FT-IR), nitrogen adsorption–desorption analyses, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques confirmed the grafting of PNVF onto MCF. The N 2 adsorption–desorption studies showed that the textural properties of the pristine MCF decreased as the amount of grafted PNVF increased confirming the deposition of polymer into silica. However, according to SAXS, SEM, and TEM studies, the mesostructure of MCF was maintained even after acid hydrolysis of PNVF and its subsequent neutralization to obtain PVAm. Highlights Amine polymer/silica foam hybrid material was obtained. Covalent grafting of PNVF onto mesocellular silica foam (MCF). The content of the grafted PNVF was tailored by varying polymerization conditions. Grafted PNVF turns into PVAm by acid-catalyzed hydrolysis. Acid hydrolysis of PNVF does not affect the morphology of MCF.