Preparation and Structure of the LB Film for Iron(III) Salts of Long Chain Fatty Acids

Abstract

The preparation of the LB film from the monolayer spread on water surface was attempted by the use of various iron(III) salts. Iron(III) octadecylsuccinate, hydroxide dipalmitate, hydroxide distearate, tripalmitate, and tristearate were synthesized and examined for the film formation. Only iron (III) hydroxide dialkanoates permitted the formation of the LB film up to about 100 layers on a plate of Ferrotype or a glass plate at 25 mN.m^-1. It was found very difficult to built up the other iron salts to be deposited in a complete layer structure. The properties of the LB film obtained from iron(III) hydroxide distearate were characterized by means of ESCA, X-ray diffraction, and IR. The ESCA measurements suggested the presence of iron(III) hydroxide distearate molecules in the LB film. The X-ray diffraction showed that the film structure was composed of the double layer arrangements in which the interlayer distance of iron (III) ions was O.22 nm shorter than that in the powder crystals. The thermal stability was tested by measuring the LB film of 30 layers deposited directly on a ZnSe photoprism. It was found that the film structure remains unchanged at room temperature for more than 7 months after deposition. However, the film melted and was destroyed at the temperature about 20°C below the mp of the powder crystals (89°C).