Synthetic, layered nanoparticles for polymeric nanocomposites (PNCs)

This review discusses preparation and use of the synthetic layered nanoparticles in polymer matrices, i.e., in the polymeric nanocomposites (PNCs). Several types of synthetic or semi-synthetic layered materials are considered, namely the phyllosilicates (clays), silicic acid (magadiite), layered double hydroxides (LDHs), zirconium phosphates (ZrPs), and di-chalcogenides. The main advantage of synthetic clays is their chemical purity (e.g. absence of amorphous and gritty contaminants, as well as arsenic, iron, and other heavy metals), white to transparent color that assures reproducibly of brightly colored products, as well as a wide range of aspect ratios, p = 20 to ≤6000. Several large scale production facilities have been established. The synthetic clay and LDH industries are oriented toward big volume markets: catalysis, foodstuff, cosmetics, pharmaceuticals, toiletry, etc. The use of these materials in PNCs is limited to synthetic clays and LDHs, mainly for reinforcement, permeability control, reduction of flammability, and stabilization, e.g. during dehydrohalogenation of chlorinated macromolecules. The use of lamellar ZrPs and di-chalcogenides is at the laboratory stage of functional polymeric systems development, e.g. for electrically conductive materials, catalysts or support for catalysts, in photochemistry, molecular and chiral recognition, or in fuel cell technologies, etc.