Properties of steel surfaces coated with organic molecules

Superhydrophobic state is one of the most interesting and attractive topic in these years due to the wide application possibilities. Roughness and surface tension are the main parameters to be controlled to obtain a surface with hydrophobic properties. The topic of this thesis is to investigate how substrate roughness and coating deposition parameters influence wettability properties. Different chemo-physical surface properties were performed by creating different substrate roughness and by applying different coatings. As substrate has been chosen mild carbon steel, use both as received and after sandblasting treatment. Over these substrates a thin organic film coating has been applied. The employed coatings were purchased or were synthesized and characterized in laboratory. Their deposition procedure was made of three main steps: cleaning, etching and post thermal treatment. Etching time and post thermal treatment has been widely surveyed to respectively improve active sites concentration on the metallic substrate and to improve the strength of anchoring bonding. For each kind of coating, three different alkyl chain lengths have been studied to understand their role in the wettability. Optical contact angle analysis was used to establish wetting properties, atomic force microscopy (AFM) was used to characterize samples mechanical properties (roughness and coatings adhesion force). Glow discharge optical emission spectroscopy (GDOES) characterization was used to quantify coatings thickness and to determine their chemical composition. Electrical samples properties were studied by electrochemical impedance (EI), while surface morphologies were detected by using scanning electron microscopy (SEM).