2. Clay Minerals as Natural Nanosheets

Clay mineral particles consist of nanosized layers which are negatively charged due to isomorphous substitution. Exchangeable cations in the interlayer space compensate this negative charge and are exchangeable by almost any cationic species: inorganic, organic, polymeric. These properties allow for the synthesis of nanosized films with known techniques: casting, spin coating, layer-by-layer assemblage, Langmuir–Blodgett. The molecules in the interlayer space of the films adopt specific organizations, depending on their size and the charge density of the clay minerals. The molecule–clay mineral surface interaction suppresses molecular aggregation in the interlayer space. This opens the way to formation of functional films. The functionality of these films depends on the functionality of the molecule, the molecular organization in the interlayer space, and the organization of the clay mineral layers in the films.