Influence of molecular packing on the corrosion inhibition properties of self-assembled octadecyltrichlorosilane monolayers on silicon

• Molecular packing plays an important role in determining SAM film properties.
• Loose-packed OTS monolayers on silicon were corroded by exposure to KMnO4.
• Dense-packed OTS SAM films exhibited excellent corrosion protection efficacy.

The corrosion inhibition properties of octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs) on silicon were investigated. Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), contact angle (CA), and lateral force microscopy (LFM) were used to determine the OTS film formation time, packing density, and corrosion protection efficacy. The OTS films reached adsorption saturation after 15 s; however, the molecular density continued to increase up to 24 h. The films were exposed to the strong oxidant KMnO4, and while 15-s film samples exhibited corrosion after a 1 min exposure, samples with films grown for 24 h were protected even after 24 h.