effect of teos concentration on the surface characteristics and hydrophobic performance of silica-based coatings

This study investigates the effect of tetraethyl orthosilicate (teos) concentration on the structural and surface properties of silica-based coatings developed for corrosion protection of mild steel. silica particles were synthesized via a soft-templated sol–gel method using varying teos loadings, and subsequently functionalized with methyltrimethoxysilane (mtms) to induce hydrophobicity. the resulting materials were characterized by xrd, ftir, sem-eds, and water contact angle (wca) measurements. xrd confirmed the formation of amorphous or partially crystalline sio₂ phases, while ftir analysis indicated the presence of both hydrophobic –ch₃ groups and hydrophilic si–oh functionalities. sem-eds analysis indicated that higher teos concentrations resulted in larger, smoother particles with lower surface carbon content, likely due to reduced mtms coverage. wca measurements demonstrated that lower teos concentrations increased surface area and roughness, facilitating greater methyl group grafting and enhanced hydrophobicity. the a1 and a2 samples exhibited the highest wca values (87.6° and 84.4°, respectively), indicating improved water repellency. further studies could explore alternative silane coupling agents or dual-functional silanes to enhance the grafting of hydrophobic groups on high-teos surfaces.