Langmuir and Langmuir–Blodgett films of aromatic amphiphiles

ABSTRACT Amphiphiles are molecules that contain two discrete segments – a water-soluble hydrophilic part (head-group) and a water-insoluble hydrophobic part (tail). The structural variations possible with the head-group part are enormous and numerous amphiphiles have been designed in this way. On the other hand, the structural variations feasible for the hydrophobic tail part are rather limited. Saturated aliphatic hydrocarbon chains are predominantly found in most of the amphiphiles. Unsaturated aliphatic hydrocarbon chains (n-alkenyl or n-alkynyl chains) also serve as the hydrophobic tail part in many of the amphiphiles. Amphiphiles, wherein the hydrophobic tail part is made up of aromatic moieties (alone or in combination with aliphatic chains) are less frequently encountered compared to the other two types. Many of these aromatic amphiphiles, the focus of this review article, are known to form different types of assemblies including Langmuir and Langmuir-Blodgett (LB) films. In this review, we will provide an account of the different types of aromatic amphiphiles that have been reported and highlight their properties and applications at the air–water and air–solid interfaces.