The controlled transfer of organized monolayers of amphiphilic molecules from the airwater interface to a solid substrate was the first molecular-scale technology for the creation of new materials. However, the potential benefits of the technology envisioned by Langmuir and Blodgett in the 1930s have yet to be fully realized. Problems of reproducibility and defects and the lack of basic understanding of the packing of complex molecules in thin films have continued to thwart practical applications of Langmuir-Blodgett films and devices made from such films. However, modern high-resolution x-ray diffraction and scanning probe microscopy have proven to be ideal tools to resolve many of the basic questions involving thin organic films. Here, studies are presented of molecular order and organization in thin films of fatty acid salts, the prototypical system of Katharine Blodgett. Even these relatively simple systems present liquid, hexatic, and crystalline order; van der Waals and strained layer epitaxy on various substrates; wide variations in crystal symmetry and interfacial area with counterions; modulated superstructures; and coexisting lattice structures. The wide variety of possible structures presents both a challenge and an opportunity for future molecular design of organic thin-film devices.

https://science.sciencemag.org/content/sci/263/5154/1726.full.pdf

Langmuir-Blodgett films

http://kristiankjaer.dk/krkj/Some_Publications/Principles_GIXD_n_Monolayers_Air-Water__PhysRep_vol_246_p_251-313_1994.pdf

Principles and applications of grazing incidence X-ray and neutron scattering from ordered molecular monolayers at the air-water interface

https://www.cell.com/biophysj/pdf/S0006-3495(99)76998-5.pdf

Condensed complexes of cholesterol and phospholipids

Organized ceramic/polymer nanocomposites were designed from montmorillonite clay (Mont), cationic poly(ethylenimine) (PEI) or poly(dimethyldiallylammonium chloride) (PDDA) and proteins. Ordered multilayers with a controllable number of layers were prepared by alternate adsorption of delaminated montmorillonite (0.03 wt % dispersion) and polycations. Quartz crystal microbalance, X-ray diffraction, and scanning electron microscopy monitoring of the assembly have shown formation of ordered films with bilayer thickness of 3.3 nm for Mont/PEI and 3.6 nm for Mont /PDDA. Increased viscosity near the substrate was recognized at higher concentrations of Mont (1 wt %). At these and higher concentrations super hydrated (water content 99.4 wt %) solid gels of Mont and polycations were produced by mixing of their aqueous dispersions. Its open card-house structure was revealed with a scanning electron microscopy study.

Formation of Ultrathin Multilayer and Hydrated Gel from Montmorillonite and Linear Polycations.

Langmuir−Blodgett film structure

https://www.cell.com/biophysj/pdf/S0006-3495(91)82182-8.pdf

Phases of phosphatidyl ethanolamine monolayers studied by synchrotron x-ray scattering.

Thickness and temperature dependent structure of Cd arachidate Langmuir-Blodgett films

Precise determination of tilt angles by x-ray diffraction and reflection with arachidic acid monolayers

Structural changes before and during desorption of Langmuir-Blodgett films

Langmuir-Blodgett mono- and multilayers of ferric stearate have been formed on oxidized silicon wafers. Thermodesorption of these layers was investigated by conversion electron Mossbauer and photoelectron spectroscopy and some complementary methods. Heating of samples in air up to 523 K leads to a desorption of the fatty acid chains, while the ferric ions are left on the substrate surface. These ions do not cluster laterally like it was found for Cd ions. They form a rather homogeneous, closed oxidic layer. This well defined layer may be used afterwards for further studies of surface reactions as well as interface and intra-layer interactions. The surface iron ions were found to exhibit a reasonably high recoilless fraction. Therefore, Mossbauer spectroscopy allows to follow chemical, structural, and magnetic changes of the iron ions even if the surface is covered by less than one monolayer.

P. Tippmann-Krayer

Papers

Phases of phosphatidyl ethanolamine monolayers studied by synchrotron x-ray scattering.

Thickness and temperature dependent structure of Cd arachidate Langmuir-Blodgett films

Precise determination of tilt angles by x-ray diffraction and reflection with arachidic acid monolayers

Structural changes before and during desorption of Langmuir-Blodgett films

CEMS/XPS study of iron stearate Langmuir-Blodgett layers