engleski

The Impact of Bronze Composition on Properties of Self-Assembled Monolayers of Phosphonic Acids

Self-assembled monolayers (SAMs) of long-chain organic acids are formed by adsorption of acid on the surface of oxide-covered metal, resulting in acid-base reaction between metal oxide and acid. This reaction is followed by the self- organization of alkyl chains which creates a very thin and compact film. Due to their unique properties, they are used in many fields, from nano fabrications, sensorics, electrocatalysis to microelectronics. In addition to the listed fields, they have also proven to be good corrosion inhibitors on various metal substrates. Given that corrosion is a significant problem globally, SAMs are emerging as a potential solution to this global problem. There are many parameters in the preparation of SAMs that can influence the quality of the formed film, but in this work we will deal with the influence of the composition of the bronze substrate on their formation. More specifically, we will form films on pure copper and several bronzes of varying composition so that we can see how and to what extent individual alloying element affect the quality and arrangement of the SAMs. This information is important given that better arranged films provide stronger and longer lasting protection. In order to obtain a compact well-ordered film which will provide long term protection, SAMs preparation procedures consist of bronze pretreatment and phosphonic acid adsorption by dip-coating followed with drying period. Protective properties of phosphonic acid SAMs are examined by linear polarization measurements and electrochemical impedance spectroscopy. These measurements are carried out in simulated acid rain (0.2 g/L NaNO3 + 0.2 g/L Na2SO4 + 0.2 g/L NaHCO3 at pH 5) which simulates the rain in urban atmosphere. The surface of modified samples is also examined by scanning electron microscopy and Fourier transform infrared spectroscopy in order to verify adsorption of phosphonic acid on metal and formation of an ordered organic layer.

bronze, self-assembled monolayers, corrosion protection

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