Fabrication Of Hybrid Films With The Low Surface Energy On Metallic Substrates And Research On Anti-corrosion Properties

Metal corrosion causes great economic loss and damage to industry and society. With the development of the industry and scientific technologies, corrosion science becomes more and more important in national economy. Therefore, the protect of metal is intimately involved with the people's livelihood and sustainable development of economy. As we all know, the beginning of metal corrosion is mainly located in the interface between metal and environment. So we can prevent the metal corrosion at a certain extent by metal surface treatment.In this paper,1-dodecanethiol film and 1-dodecanethiol/tetradecanoic acid hybrid film have been obtained on copper substrates. At the same time, the surface structure of the?lm was characterized by water contact angle measurement, scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDX). The result shows that the sole 1-dodecanethiol film is uniform and compact, and the contact angle is 150°. However, when formed 1-dodecanethiol/tetradecanoic acid hybrid film, the film is more compact and the contact angle is larger than 160°. The electrochemical impedance spectroscopy and potentiodynamic polarization test demonstrate that the anti-corrosion property of surface-modi? ed copper substrate is greatly improved, especially for the 1-dodecanethiol/tetradecanoic acid hybrid?lm. Moreover, the competitive adsorption process and adsorptive geometry of hybrid?lm were calculated by Gaussian(R) 03 program package which are well explained the results of contact angle measurement, SEM, and EDX. But the shortcoming is that the films formed on copper substrate are not stable and easy to fall off.Recently, mussel adhesive proteins (MAPs) excreted by marine mussels have attracted much attention because of their ability to form strong adhesive interaction with various substrates in wet environment. Catechol group plays the important role in the adhesive process. Dopamine has catechol group, so it can be firmly absorbed on metal substrate. In addition, the dopamine coating layers could be further modi?ed by the strong covalent interaction between thiol-or amine-containing molecules.Based on the above advantage and disadvantage, the 1-dodecanethiol film was steadily absorbed on copper substrate via the easily-absorbed dopamine. The formation and surface structure of the?lm were characterized by X-ray photoelectron spectroscopy (XPS), SEM, and EDX. The results show that the dopamine is successfully absorbed on copper substrate. And monolayer formation on the poly(dopamine) sublayer is believed to involve reaction between terminal thiol groups and the poly(dopamine) coating via Shiff-base and Michael addition chemistry, in a manner analogous to the reaction between thiols and noble metal films in the formation of conventional SAMs. The contact angle measurement shows that when dopamine is absorbed on copper substrate, the copper surface is hydrophilic,-but the surface is hydrophobic when 1-dodecanethiol absorbed because of the alkyl chain. The corrosion behavior of the functional?lms was evaluated by the electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements and the results indicate that 1-dodecanethiol film based on the adhesive of poly(dopamine) indeed reduces the corrosion of copper. What's more, the stability of the dopamine/1-dodecanethiol hydrophobic?lm was evaluated in seawater and there is no obvious?uctuation of the contact angles on the surface after storage about 20 days, showing almost no effect of Cl- on the surface.In order to test the universal property of the method,1-dodecanethiol was absorbed on 304 stainless steel (304SS) whose sttucture is different from copper. At the same time, the film surface was evaluated through XPS,AFM and contact angle measurement. The results have shown that the 1-dodecanethiol film was indeed formed on the poly(dopamine)-coated copper surface. Meanwhile, the electrochemical impedance spectroscopy and potentiodynamic polarization are shown that the anti-corrosion property of surface-modi? ed 304SS substrate is greatly improved.