Octadecyltrichlorosilane is widely used as a surface modification agent to create hydrophobic coatings on various substrates. It is applied to glass, silicon, and other oxide surfaces to form self-assembled monolayers that repel water and reduce surface energy. This property makes it valuable in the production of water-resistant materials, anti-fogging coatings, and protective layers for electronic devices. Additionally, it is utilized in the development of microfluidic devices to control fluid flow and in the fabrication of sensors to enhance their performance by minimizing nonspecific adsorption. Its ability to modify surface properties also finds applications in the biomedical field for creating biocompatible coatings on implants and medical instruments.