Structural Synthesis of Hydrophilic and Hydrophobic Silica for its use in Food Packaging Films

This study focuses on the synthesis of silica-based organic hybrids that can be used as fillers in plastics or adhesives with the aim of reducing their cost and improving the mechanical properties. Essentially, this work is intended to develop hybrid materials based on silica, with different surface properties modified by techniques such as functionalization using 3-aminopropyl triethoxysilane (APS) and 1,1,1,3,3,3–hexamethyldisilazane (HMDS) reagents as SiO2 modifiers with a view to their future employment as fillers in plastic films to be used as covers for different fruits. The materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM), textural properties, wettability measurements, and potentiometric titration with n-butylamine. Hydrophobic silicas were obtained when, in their synthesis, APS and HMDS were added as modifiers. Besides, their addition caused a large effect on the textural characteristics. The titration of the acidic sites of the modified silicas showed a sharp decrease in acidity compared to the unmodified silica. The TEM micrographs of the synthesized samples showed that the increase in HMDS amount aided to maintain the spherical shape of pure silica, increasing the formation of agglomerations and the primary particle size.