Influence of different fatty acids on the wettability, self-cleaning and anti-corrosion behavior of superhydrophobic surfaces obtained with LDH on aluminum

Abstract

The present study aims to evaluate the influence of different fatty acids on the wettability, self-cleaning, and anti-corrosion properties of aluminum alloy 5052 (AA5052). Superhydrophobic surfaces are developed through acid etching with HCl solution, in-situ growth of zinc layered double hydroxides (ZnAl LDH), and chemical modification with three different fatty acids: lauric (LA), myristic (MA), and stearic (STA). SEM images show the formation of micro-nanometric binary structures of flowers and petals covered by a thin film, which is associated with ZnAl LDH formation and fatty acid deposition through EDS. The contact angle (CA) values indicate the change in the wettability of the surfaces after chemical modification, ranging from CA = 0° to CA > 160°. Visual tests reveal notable disparities in buoyancy and self-cleaning behaviors, liquid adhesion, and the formation of plastrons between the coated and uncoated samples. The results demonstrate the influence of the fatty acid carbon chain size on the CA and corrosion resistance efficiency (IE) in saline environment (NaCl 0.6 mol/l), with the STA sample exhibiting the best performance (CASTA = 164°; IESTA = 99.98 %) followed by MA (CAMA = 162°; IEMA = 99.27 %) and LA (CALA = 160°; IELA = 81.24 %). Future researchs will focus on obtaining self-healing properties and the durability of the coatings will be evaluated using accelerated testing methods.