Preparation of layered double hydroxides and their applications as additives in polymers, as precursors to magnetic materials and in biology and medicine

Abstract

In recent years layered double hydroxides (LDHs), also known as hydrotalcite-like materials, have attracted considerable interest from both industry and academia. In this article, we discuss methods of preparing LDHs with an emphasis on the way in which particle size and morphology can be controlled with regard to specific target applications; scale-up of one such preparation procedure is also described. In addition, we review selected applications of LDHs developed by our own and other laboratories.

Structural Synthon Approach to Predict the Possible Polytypes of Layered Double Hydroxides

“…For instance, the stacking sequence AC-AC-AC…… 1H is given the symbol 1H, to describe a one layer polytype of hexagonal symmetry and '-' denotes an octahedral interlayer site. All two layer polytypes have hexagonal symmetry: AC=CA=AC=CA……2H 1 AC-AB-AC-AB…….2H 2 AC=CB-AC=CB…….2H 3 .…”

“…[2] Among the layered materials, layered double hydroxides (LDHs), have received a great deal of attention, on account of their applications in catalysis, sorption, anion exchange, water purification and in medicine, as agents for drug delivery. [3][4][5][6] The structure of the LDHs is derived from that of mineral brucite, Mg(OH) 2 . [7] Brucite comprises a hexagonal packing of OH -ions in which Mg 2+ ions occupy alternative layers of octahedral sites.…”

Synthetic, layered nanoparticles for polymeric nanocomposites (PNCs)

“…[176][177][178] LDHs have been discussed in several edited books 19,179,180 and reviews. 36,[181][182][183][184] They are also discussed in the PNC monograph. 1 Costantino et al 185 prepared a series of iso-structural LDHs of the type Mg-Al, Zn-Al, and Ni-Al with diverse properties.…”

“…as precursors for magnets, heat retention additive in horticultural plastic films, flame retardants, HCl absorbing agents for poly(vinyl chloride) (PVC) and other halogenated polymers or POs, adsorbing agents for dyes, pigment dispersion stabilizers for coloring polymers, in biology and medicine for the storage, delivery and controlled release of pharmaceuticals and other biomolecules, as sensing materials for determination of water level, toxic additives, as biosensors, for electrodes, as catalysts for polymerization or decomposition of noxious gases, etc. 184 LDHs are commercially manufactured (e.g. by FCC in China, Sü d Chemie and Sasol in Germany, Ciba in Switzerland, Akzo Nobel, Dulso Šal'a, Slovakia, and Reheis Chemical Co. in the USA) from purified salts, or minerals such as brucite, Mg(OH) 2 , or quasicrystalline boehmite, AlO(OH), 175 Fig.…”

Facile synthesis of nanostructured LiFePO4/C cathode material for lithium-ion batteries

“…The mixing takes place in a very short time in the liquid thin film between the rotor and stator leading to nuclei which have an equal length of time to grow prior to aging, resulting in a narrow range of particle diameter. Subsequent aging allows the nuclei to grow together at approximately the same rate, giving a material containing particles with a narrow size distribution [12]. Uniform small particles can favor precursor and LiOH well-mixing easily.…”