Structure and Stability of Self-Assembled Monolayers for Octadecanethiol Adsorbed onto Flame-Annealed Gold Substrate and Its Potential Application to Microfluidics

Self-Assembled Monolayers (SAMs) derived from the adsorption of organothiols onto gold have been extensively investigated for studying their potential applications to Micro- and Nanofluidics system. However, nearly all applications rely on SAMs\´ stability. Because high energy gold is easy to absorb organic contaminant from ambient, totally wetting gold surface can not be obtained in the laboratory environment. Flame annealing the gold surface before adsorption not only remove the organic contaminant, it also shaves the "rolling hills" on the evaporated gold surface. SAMs formed on annealed gold surface have better structure and stability than those formed on evaporated gold. These properties will be helpful for potential application on microfluidics system as a surface modification. Ex situ spectroscopic ellipsometry, and Fourier Transform Infrared (FTIR) were used to characterize the structure of SAMs.