Fabrication and evaluation of hydrophobic silica thin films synthesized from TEOS and TMCS with AgNO3 integration for improved antibacterial activity

• Hydrophobic silica thin films were synthesized with TEOS:TMCS (3:6) and AgNO₃. • FTIR confirmed higher Si–O–Si/Si–OH ratios, indicating strong hydrophobicity. • AgNO₃ films showed antibacterial activity, stronger against S. aureus than E. coli . Research on the synthesis of silica thin film with variations in TMCS volume and AgNO 3 concentration variations has been carried out to determine the suitable composition for producing hydrophobic silica thin films with antibacterial properties. Trimethylchlorosilane (TMCS) was chosen as the silylation agent because it reacts with Si-OH and forms Si-O-Si(CH 3 ) to enhance the hydrophobicity. Silver nitrate (AgNO₃) was used to introduce antibacterial functionality by releasing Ag⁺ ions that can inactivate microbial cells and damage cell membranes. Silica thin films were then characterized through water contact angle method to determine hydrophobicity, FTIR to identify the functional groups, and antibacterial activity test. The results showed that the composition of 3:6 (TEOS:TMCS) with an AgNO₃ concentration of 0.04 M produced films with the highest contact angles of 103.26° and 118.71° with and without the addition of AgNO₃, respectively. The hydrophobic thin film before and after calcination exhibited a higher Si–O–Si/Si–OH area ratio, indicating hydrophobic characteristics. The antibacterial activity test of thin film xerogel with the addition of variations in AgNO 3 concentration shows inhibition of S. aureus and E. coli growth. These findings suggest that hydrophobic silica thin films incorporating AgNO₃ have potential for surface protection applications.