2D M-nanoaggregates in langmuir layers of calamite mesogen

摘要

It is shown that a representative of calamite mesogens, 4-(4'-nonyloxyphenylazo)cinnamic acid (NOPCA), forms floating monolayers on the surface of water at initial surface coverage c a parts per thousand currency sign 22.8%; their structural elements are 2D face-on M-nanoaggregates. The main structure characteristics and properties of M-monolayers (the size of M-nanoaggregates formed in the layer, number of molecules in them, distance between the aggregates, water content in the aggregates and between them, compressibility, and pressure and surface concentration ranges of existence of the aggregates) are determined. It is shown that this compound manifests a specific behavior in Langmuir layers that is different from most of the compounds studied so far due to particularities of the molecular structure and formation of hydrogen bonds in layers on the surface of water. The formation of two types of floating NOPCA monolayers is observed and changes of their characteristics are studied in successive "compression-decompression" cycles.