Hectorite: Synthesis, modification, assembly and applications

Hectorite (Na0.3Mg2.7Li0.3Si4O10(OH)2) is a trioctahedral clay mineral with peculiar cation exchange capacity, surface reactivity and adsorption, and easy delamination in water into individual nanolayers, which can then re-assemble in various ways. The aqueous dispersion of hectorite exhibits exclusive rheological and thixotropic properties. The paper reviews recent progress in the synthesis, modification, assembly and applications of hectorite. The present methods for synthesizing hectorite are hydrothermal synthesis, melt synthesis and structure-directed synthesis. Modification of hectorite can be made by ion exchange, intercalation, pillaring and grafting. Layer-by-layer assembly, template assembly and hierarchical assembly have been used to formed a variety of hectorite-containing hybrids and nanocomposites such as films, membranes, capsules and Janus nanoparticles. Hectorite and hectorite-derived materials can be used as adsorbents, catalysts, fluorescent reporters, hydrogels, and biomaterials. Literature survey has indicated that hectorite has been successfully used as rheological and thixotropic materials, and are being developed to be used in battery, fluorescent reporters, drug vehicles and tissue engineering.