Inorganic layered double hydroxides

Choy, J.H., Kwak, S.Y., Jeong, Y.J. and Park, J.S. (2000) Inorganic layered double hydroxides as nonviral vectors. Angewandte Chemie-Intemational Edition, 39, 4042-4045. 

Layered materials are of special interest for bio-immobilization due to the accessibility of large internal and external surface areas, potential to confine biomolecules within regularly organized interlayer spaces, and processing of colloidal dispersions for the fabrication of protein-clay films for electrochemical catalysis [83-90], These studies indicate that layered materials can serve as efficient support matrices to maintain the native structure and function of the immobilized biomolecules. Current trends in the synthesis of functional biopolymer nano composites based on layered materials (specifically layered double hydroxides) have been discussed in excellent reviews by Ruiz-Hitzky [5] and Duan [6] herein we focus specifically on the fabrication of bio-inorganic lamellar nanocomposites based on the exfoliation and ordered restacking of aminopropyl-functionalized magnesium phyllosilicate (AMP) in the presence of various biomolecules [91]. 

Keywords Layered double hydroxide (LDH) Organic inorganic hybrids ... 

Bhaumik, A., Samanta, S. and Mai, N.K. (2005) Efficient removal of arsenic from polluted ground water by using a layered double hydroxide exchanger. Indian Journal of Chemistry, Section A Inorganic, Physical, Theoretical and. Analytical Chemistry, 44(7), 1406-9. 

In all previous cases, V was incorporated in a monomeric form. There are also methods to introduce oligomeric V into inorganic structures. Choudary et al. (48) advocated the use of a montmorillonite, pillared with V oligomers (V-PILC). V-PILC catalyzes the epoxidation of allylic alcohols with i-BuOOH. Oligomeric V is also used to pillar anionic clays such as layered double hydroxides (LDHs) with decavanadate anions (VioOjg) (49). 

Provided in this chapter is an overview on the fundamentals of polymer nanocomposites, including structure, properties, and surface treatment of the nanoadditives, design of the modifiers, modification of the nanoadditives and structure of modified nanoadditives, synthesis and struc-ture/morphology of the polymer nanocomposites, and the effect of nanoadditives on thermal and fire performance of the matrix polymers and mechanism. Trends for the study of polymer nanocomposites are also provided. This covers all kinds of inorganic nanoadditives, but the primary focus is on clays (particularly on the silicate clays and the layered double hydroxides) and carbon nanotubes. The reader who needs to have more detailed information and/or a better picture about nanoadditives and their influence on the matrix polymers, particularly on the thermal and fire performance, may peruse some key reviews, books, and papers in this area, which are listed at the end of the chapter. 

A final example of a stereoselective heterogeneous catalytic system is the work of Laycock, Collacott, Skelton and Tchir.17 Layered double hydroxide (LDH) synthetic hydrotalcite materials were used to stereospecifically polymerize propylene oxide [PO] to crystalline isotactic and liquid atactic poly(propyleneoxide) [PPO]. These authors suggest that the LDH surface acts as other inorganic or organometallic coordination initiators or catalysts by providing specific surface orientations for propylene oxide monomer. X-ray powder diffraction showed some loss of crystallinity after calcination and X-ray photoelectron spectroscopy showed an enhancement of Mg/Al content due to restructuring of the Mg and A1 surface atoms. The surface was also rich in Cl ... 

Layered silicate clays intercalated by pillaring poly-oxocations are precursors to an important class of mi-croporous catalysts. Smectite clay was the only host structure known to be pillarable by purely inorganic oxo ions. Recently, layered double hydroxides (LDH) pillaring oxo ions were reported by Pinnavaia and coworkers [79, 80]. 

Chibwe, K. and Jones, W. (1989). Intercalation of organic and inorganic anions into layered double hydroxides. J. Chem. Soc., Chem. Commun., 926. 

Wang, J. D., Serrette, Y., Tian, Y. and Clearfield, A. (1995). Synthetic and catalytic studies of inorganically pillared and organically pillared layered double hydroxides. Appl. Clay Sci. 10, 103. 

Fudala, A., Palinko, I. and Kiricsi, I. (1999). Preparation and characterization of hybrid organic-inorganic composite materials using the amphoteric property of amino acids amino acid intercalated layered double hydroxide and montmorillonite. Inorg. Chem. 38, 4653. 

Different hybrid materials formed by insertion of organic polymers into inorganic substrates have been prepared. Layered materials are well known as host matrices for the incorporation of a large variety of polymeric organic species. Generally, the inorganic part is finely dispersed or exfoliated within the polymer, but, alternatively, the polymer can form laminae intercalated in laminar solids. This is the case for layered double hydroxides (LDHs, see Chapter 6), whose structure is closely related to that of the brucite, Mg(OH), in which the partial substitution of some of the divalent... 

Yarger, M.S., Steinmiller. E.M.P., and Choi, K.-S. 2008. Electrochemical synthesis of Zn-Al layered double hydroxide (LDH) films. Inorganic Chemistry 47, 5859-5865. 

Trifiro, K. and Vaccari, A. (1996). Hydrotalcite-like Anionic Clays (Layered double Hydroxides). In J.L. Atwood, J.E.D. Davies, D.D. MacNicol, F. Vogtie. J-M. Lchn, G. Alberti, T. Bein, (Eds.), Comprehensive Supramolecular Chemistry Solid State Supramolecular Chemistry Two and Three-dimensional Inorganic Networks (VoL7, pp. 251-291). Oxford, UK Pergamon. 

Layered organic-inorganic hybrid nanocomposites are of significant interest to researchers in terms of their applications in science and technology. These include a broad class of chemical compounds such as, (1) - layered double hydroxides, (2) - hydroxyl double salts (HDS s) and (3) - hydroxides of metals, in which various organic anions were intercalated in the space between the layers. 

Bin-Hussein, M. Z. Yahaya, A. H. Shamsul, M. SaUeh, H. M. Yap, T. Kiu, J. Acid fuchsin-inter-leaved Mg-Al-layered double hydroxide for the formation of an organic-inorganic hybrid nanocomposite. Mater. Lett. 2003, 58, 329-332. 

Zhang, H. Zou, K. Sun, H. Duan, X. A magnetic organic-inorganic composite Synthesis and characterization of magnetic 5-aminosalicyhc acid intercalated layered double hydroxides. J. Solid State Chetn. 2005,178, 3485-3493. 

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