An extremely rapid dip-coating method for self-assembly of octadecylphosphonic acid and its thermal stability on an aluminum film

Abstract

We introduce a dip-coating method for preparing self-assembled monolayers (SAMs) of octadecylphosphonic acid (OPA) on hydrophilic substrates by selecting anisole (methoxybenzene) as the solvent, which has a dielectric constant of 4.3. We demonstrate that full-coverage OPA SAMs are formed in a couple of seconds on a cleaved mica substrate upon its dipping in a 1 mM OPA solution in anisole. In order to develop applications of this extremely rapid coating approach in surface engineering, we investigate the thermal stability of OPA SAMs dip-coated on a UV/ozone-cleaned aluminum film using water contact angle measurements and time-of-flight secondary ion mass spectrometry. It was clarified that the OPA SAMs annealed in air at up to 200 °C exhibited excellent hydrophobicity and the degradation mechanism is oxidation of the alkyl chains.