Comparative investigation of Langmuir–Blodgett films and Self-Assembled Monolayers on metal surfaces

We studied a single chain thiol and a double chain dithiocarbammate with alkyl chains of comparable length and sulphur containing head-groups. We preliminary characterised the spreading monolayers of both compounds at the water–air interface. The formation of self-assembled films on metal substrates as a function of lipid concentration and immersion time was investigated by contact angle, ellipsometric and FT-IR measurements. The same techniques were used to characterise Langmuir–Blodgett (LB) films of the same substances. The results showed that the behaviour at water–air interface strongly conditioned the properties of the resulting LB films, whereas the structural features of Self-Assembled Monolayers (SAM) samples depended mainly on the adsorption sites distribution of the metal surface.