LangmuirBlodgettTechnik

Langmuir-Blodgett (LB) technique is a method for creating highly uniform, ultrathin films by transferring a Langmuir monolayer from the air–water interface to solid substrates. It was developed in the 1930s by Irving Langmuir and Katharine Blodgett and is used to study and exploit two-dimensional molecular organization at interfaces.

A spread material, typically amphiphilic molecules such as fatty acids or phospholipids, is dissolved in a volatile solvent and deposited on a clean water subphase in a Langmuir trough. The monolayer is compressed with movable barriers to a chosen surface pressure, characterized by a surface pressure–area isotherm. A substrate is then immersed vertically into the subphase, withdrawn, or both, so that the monolayer adheres to the substrate, forming a deposited film. Each dipping/withdrawal cycle adds one monolayer; repeating cycles enable multilayer stacks with controlled thickness and orientation.

A wide range of organic and inorganic materials has been transferred, including fatty acids, phospholipids, conjugated polymers, silica nanoparticles, and organic-inorganic hybrids. Variants include Langmuir-Blodgett and Langmuir-Schaefer deposition, with the latter using horizontal contact to transfer layers. The technique supports control over molecular tilt, density, and layering sequence, enabling tailored optical, electronic, and barrier properties.

Practical considerations include cleanliness of the trough and subphase, solvent residues, temperature effects, and surface contamination, which can affect transfer ratio and film continuity. The transfer ratio is typically near unity when deposition conditions are well chosen. LB films are used in molecular electronics, sensors, membranes, nonlinear optics, and biosensors, where precise layering and orientation are beneficial.