Preparation and functionality of clay-containing films

This article provides an insight into state-of-the-art advances in the preparation and functionalization of clay-containing thin films. Layered clay minerals and their synthetic counterparts such as cationic montmorillonite, saponite, laponite and anionic layered double hydroxides are often used as main components or functional fillers in the hybrid films. Strategic assembly of clay minerals or layered double hydroxides with functional molecules has led to a variety of nanostructured clay-containing hybrid films. Frequently used approaches are the solvent casting, the spin-coating, the layer-by-layer (LbL) assembly and the Langmuir-Blodgett (LB) techniques. The type of clay mineral, solvent, pH, organic components and functional molecules generally play a pivotal role in the formation and structure of a desired functional film. Different processes result in differences in the thickness, surface morphology and internal structure in the resultant clay-containing films. Functional polymers, dye molecules, transition metal complexes and protein molecules and even their combination have been exploited to fabricate and functionalize clay-containing films. Many studies have suggested that the functional clay-containing films have potential applications in many areas such as catalysis, modified electrodes and optoelectronic devices, anti-corrosion and packaging materials. Finally, the prospects for the future preparation and applications of clay-containing films are discussed.