Comparative study of Langmuir- and Langmuir–Blodgett layers of amphiphilic carboxylic- and hydroxamic acids

The goal of the work presented here was to study the properties of mono- and multilayers of different amphiphiles in order to choose the appropriate compounds and experimental conditions, which would allow the formation of highly ordered, well-packed protective films on copper which could control the chemical and microbiological corrosion. Previous investigations of our group have shown the anticorrosion efficiency of some alkyl hydroxamic acid nanolayers. Here, we present the experimental results performed with several, systematically changed long-chained carboxylic (CA) and hydroxamic acids (HA), saturated and unsaturated ones, respectively, in order to find the most proper amphiphiles for preparation of compact nanolayers.Essential differences were found between the isotherms of saturated and unsaturated amphiphilic CAs and HAs, which were even more visible on the compression moduli graphs. The liquid state was much longer at the saturated CAs than at the saturated HAs. Additional two carbon atoms in the chain resulted in an increased collapse pressure at the CAs and HAs, as well. The change in the temperature affected the isotherms both of the CAs’ and HAs’ layers. Sum frequency generation spectroscopic (SFS) measurements revealed high molecular ordering in the films of the saturated CAs and HAs, while low ordering in the films of the unsaturated analogues.The results predict that only the nanolayers of the saturated carboxylic and hydroxamic acids could be applied as potential anticorrosive and bacterial adhesion preventing coatings.