Enhanced tribology durability of a self-assembled monolayer of alkylphosphonic acid on a textured copper substrate

A simple two-step process was developed to render the copper surface with lower friction and long durability. The copper substrate was immersed in a 0.01 M NaOH solution to fabricate a textured Cu2O film. A self-assembled monolayer of alkylphosphonic acid was then deposited on the Cu2O film to acquire high hydrophobicity. Scanning electron microscopy, Fourier transform infrared microscopy and water contact angle measurements were used to analyze the morphological features, the chemical composition and hydrophobicity of freshly prepared samples, respectively. Moreover, the friction-reducing behavior of the organic-inorganic composite film sliding against steel was evaluated in a ball-on-plate configuration. It was found that the alkylphosphonic acid films on the textured Cu2O film led to decreased friction with significantly extended life. For a constant load, the increase in chain length of alkylphosphonic acid yields the films that are dramatically more stable against tribological deformation and provide low coefficients of friction over much longer periods of time.