The invention relates to a radical-initiated thiol-ene or thiol-yne “click” reaction that provides a simple and efficient route to diverse trialkoxysilanes. Trialkoxysilanes made in this way are obtained in quantitative to near-quantitative yields with high purity without any or minimal purification. A wide range of functional groups is tolerated in this approach, and even complex alkenes click with the silane precursors. The modular nature of these radical-based thiol-ene or thiol-yne “click” reactions allows a wide variety of pendant groups to be coupled to silane compounds that can then be coupled to a wide variety surfaces in order to modify their material properties. Consequently, such radical initiated thiol-ene and thiol-yne reactions provide facile and efficient methods for preparing an enormous number of surface-active functional trialkoxysilanes.