Langmuir-Blodgett (LB) monomolecular layers of alkylhydroxamic acids and alkylphosphonic acids on copper and iron substrates have been studied by X-ray photoelectron spectroscopy (XPS) and sum-frequency vibrational spectroscopy. According to the XPS results, the structures of the hydroxamic acid and phosphonic acid Langmuir-Blodgett films are very similar: the thickness of the layer of the hydrocarbon tails is typically 1.9-2.1 nm, while the layer of headgroups is about 0.3-0.35 nm thick. The tilt angle of the carbon chains is estimated to be 20-30 degrees with respect to the sample surface normal, and the molecules are connected to the substrate via their headgroups. Analysis of the P 2p and N 1s lines indicates the presence of deprotonated headgroups. The substrate Cu 2p line includes a component which can be assigned to Cu(2+) ions in a thin Cu(OH)(2) layer. The deposition of LB layers led to significant decrease of the hydroxide-related signal, which indicates that binding of the headgroups to the surface is accompanied by the elimination of water molecules. The sum-frequency spectra also clearly indicate that well-ordered monolayers can be formed by the Langmuir-Blodgett technique. Since the non-resonant background from the metal substrates renders the analysis of the spectra more difficult, model system samples on glass were prepared. It was found that the alkyl chains of the adsorbed acids predominantly adopt the all-trans conformation and form an ordered structure. Upper limits for the mean tilt angle of the terminal methyl groups are approximately 10-20 degrees.

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Protective nanolayers of alkyl hydroxamic acids deposited on a copper surface as a Langmuir -Blodgett lm (LB) or as a self assembled molecular layer (SAM) were studied in acidic and neutral sodium chloride and sodium sulphate solutions. The LB lm deposition and SAM formation on copper substrate were followed by a surface visualisation technique and by contact angle measurement. Following exposure to aggressive electrolytes the anticorrosion abilities of the monolayers and multilayers were characterised by image analysis, by the roughness of the copper surface, and by an electrochemical method.CEST/2120

Langmuir-Blodgett (LB) nanolayers of alkyl hydroxamic and phosphonic acids on glass, iron and copper surfaces were studied in the presence of different, corrosion relevant micro-organisms. The quality of monomolecular and multimolecular LB layers was characterised by dynamic contact angle measurement, atomic force microscopy and the sum frequency vibration technique. The inhibition efficiency of microbial adhesion and biofilm formation, which was analysed by the surface visualising technique, epifluorescence microscopy and microbiological methods, increased with layer thickness. There were some differences in the blocking activity of the two amphiphiles (octadecylphosphonic acid C18P and octadecanoyl hydroxamic acid C18N) applied in LB films. Their repellent activity did not differ in cooling water but, in the presence of Acidithiobacillus ferrooxidans, the C18N nanolayer inhibited the biofilm formation much better.

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Nanolayers, prepared by Langmuir-Blodgett techniques, are potential replacements of currently applied surface inhibitors. Protective effects of octadecanoyl hydroxamic-and octadecyl phosphonic acid Langmuir-Blodgett films were studied in neutral sodium perchlorate solution. The protection efficiency of these monolayers on an Armco iron surface was characterized by electrochemical methods. Both types of nanolayers effectively decreased the corrosion processes at the metal surface. The difference between the efficiencies of the applied layers could be explained on the basis of interactions between their amphiphile head groups with the Armco iron surface. The size of the head group of octadecyl phosphonic acid is larger than that of octadecanoyl hydroxamic acid, which can be attributed to the better protective efficiency of octadecanoyl hydroxamic acids.Nanolayers have been increasingly investigated in the last decade for their fundamental importance and industrial applicability. Monoand multilayers can be deposited either as a self-assembled molecular layer ͑SAM͒ or a Langmuir-Blodgett ͑LB͒ film. 1 Both techniques produce well-organized, densely packed, thin films on the metal surfaces 2 and could be used against metal corrosion. 3-14 In some cases the inhibitive activity of these two types of nanolayers was compared. 15 The inhibition efficiency of these layers depends on the material types, molecular structures, head groups, and number of the monolayers. The efficiency increases with the carbon chain length. 16 While self-assembly techniques are versatile and fast methods, Langmuir-Blodgett deposition generally allows a higher degree of control over the functional layers. This advantage has inspired researchers to explore LB deposition as a tool for the preparation of a new class of corrosion protecters. Particularly, corrosion inhibition by LB films requires a smaller inhibitor quantity and produces an efficient protection. Guo et al. 17 reported that LB layer of hexadecyl trimethyl ammonium bromide effectively inhibits steel corrosion.Phosphonic acids are excellent complexing agents. 18 They are applied as corrosion inhibitors for concrete, coatings, rubber blends, as well for metals. 19-24 Natural and synthetic hydroxamic acids exhibit biological activities 25 and are known as metal chelators. 26 Several hydroxamic acid derivates were investigated as corrosion inhibitors. 27,28 In this paper, the LB film-modified Armco iron surface is studied in order to evaluate the corrosion inhibition effect of long-length alkyl chains with various head groups. Molecules with a long carbon chain were selected due to their ability to form protective barriers through the enhanced van der Waals interactions among the alkyl chains. The efficiency of octadecanoyl hydroxamic acid ͑C18N͒ and octadecyl phosphonic acid ͑C18P͒ LB layers on the corrosion behavior of Armco iron in neutral sodium perchlorate solution were measured by electrochemical dc ͑polarization curves, cyclic voltammetry͒ and ac ͑electrochemical impedance measurem...