Thin Films, Monomolecular Layers

Abstract

Molecularly engineered materials can be fabricated from the molecular level up, and their physical properties can be both predicted and designed. Surface analytical tools enable investigations of monomolecular layers in previously unprecedented detail, leading to understanding of molecular packing and ordering. These tools also provide information to aid in understanding the relationships between the structure and properties of the individual molecule as well as of the material it forms (see Surface and interface analysis). Supramolecular assemblies are fabricated by assembling molecules that interlock in a planned, hierarchical manner, forming structures having specific desired functions. There are two principal methods. Using the Langmuir-Blodgett technique, molecular layers are formed at air-water interfaces under programmed external influence. The different kinds of monolayers are superimposed in an intelligently planned sequence, forming increasingly more complex supramolecular structures. In the self-assembly technique, layers are formed spontaneously by molecules self-organizing at a solid-liquid interface, and multilayer structures are formed only after the monolayer surface has been chemically modified.