Fabrication and Wettability of Nanoporous Silver Film on Copper from Choline Chloride-Based Deep Eutectic Solvents

Nanoporous Ag films on copper alloy substrates were fabricated by the galvanic replacement reaction from the choline chloride-based deep eutectic solvents (DES) containing AgCl. It was found that the morphologies of the films were largely dependent on AgCl concentrations and plating temperatures. Interestingly, self-assembled nanoporous network of Ag films with ligament and channel width in the range of 20-80 nm was formed on the copper alloy substrate from 0.01 M AgCl DES solution either at room temperature or at 50 degrees C. The as-deposited porous Ag films exhibited hydrophilic properties. On the contrary, after surface modification by a monolayer of n-dodecanethiol, the contact angle of porous Ag film increased largely with plating times, and a superhydrophobic surface was finally obtained with a contact angle of 160 +/- 1 degrees. Wenzel and Cassie-Baxter models were used to qualitatively illustrate the importance of the surface roughness of the Ag films to the wetting property.