Tarnish Protection for Silver Using Self-assembled Monolayers of Alkanethiols with Different Chain Lengths

Self-assembled monolayers (SAMs) of three alkanethiols on silver surface were prepared in ethanol solution. The properties of SAMs were investigated by contact angle measurement, electrochemical testing, accelerated tarnishing test and X-ray photoelectron spectroscopy (XPS). The results indicate that the hydrophobic SAMs of dodecanethiol (DT), hexa decanethiol (HDT) and octa decanethiol (ODT) were able to form on the surface of silver. And the SAMs had good protection against corrosion for the substrate. The ODT SAM had the best compactness, while the HDT SAM had the best anti-tarnishing effect.