Silane functionalization of sodium montmorillonite nanoclay: The effect of dispersing media on intercalation and chemical grafting

This study investigated the effect of various dispersing media on the silane functionalization of sodium montmorillonite nanoclay (NaMt) to evaluate each medium's effectiveness on the intercalation and chemical grafting of silane coupling agent. The amount of intercalation was estimated using the equation that was developed in our previous work based on thermogravimetric analysis. The results showed that the amount of silane intercalation was the greatest for water and glycerol media (≈1.582 mmol/g clay and ≈1.480 mmol/g clay, respectively), which was in agreement with the d001-values calculated by the XRD analysis (≈19.6 Å and ≈14.4 Å, respectively). 29Si NMR results showed a new T site in addition to Q peaks for all modified nanoclays in different dispersing media, indicating the occurrence of silane chemical grafting at the surface of the nanolayers. The AT3AQ3 in NMR spectra was used to compare the amount of chemically grafted silane in different dispersing media, a new approach for Mt material. Hydrogen-bonding solvents (water, glycerol and ethanol), and polar solvents (DMF and THF) showed greater T3 peak intensities compared to other dispersing media, indicating higher amounts of chemical grafting of silane molecules. This observation was in agreement with the broadening of FTIR peak at 1130-1000 cm− 1, which is explained by the formation of extra SiOSi bonds; that is, in turn, due to silane chemical grafting at the surfaces of the nanolayers. The silane-nanofiller interactions were correlated with the Hansen solubility parameters of different dispersing media used for the modification. This research has potential to help design and improve the nanoclay modification processes, which are used in the fabrication of clay-polymer nanocomposites.