Ordering phenomena in composite monolayers and Langmuir–Blodgett films

Abstract

The phenomenon of monolayer and Langmuir–Blodgett (LB) film stabilization via interaction with water soluble substrates like polyacrylic acid is studied. Hydrogen bonds (H-bonds) are shown to be responsible for the formation of composite monolayers based on tertiary amines and polyacid. An important influence of the contact time (before the compression) and amine amount spread on the subphase on the monolayer density is shown to be related to the diffusion of the polymer molecules up to the subphase surface. The structure of monolayers is found to depend on the amount of polyacid dissolved in water as well as on the order of introduction of the polymer into the water subphase (before or after compression). Composite monolayers based on the preprepared amine monolayer show the most dense and well aligned structure. This results in the formation of double layered LB films with highly periodic structures where polyacid amine residues are located between thin layers of H-bonded polyacid and aligned normally to the film plane. This binding of monolayers with water soluble polymers seems to be very important for the deposition of monolayers on the solid substrates and LB film preparation particularly when monolayers based on individual compounds cannot be transferred.