Organic-inorganic multilayer composites

Photochemically Induced Charge Separation in Electrostatically Constructed Organic-Inorganic Multilayer Composites... 

Keller, S.W. et al., PhotochemicaUy induced charge separation in electrostatically constructed organic-inorganic multilayer composites, in Nocera D.G. and Wishart, J.S. Editors, Photochemistry and Radiation Chemistry Complementary Methods for the Study of Electron Transfer, 1998, Adv. Chem. Ser. 254 Photochemistry and Radiation Chemistry), p. 359-379. 

Chen, Y., Xiangli, F., Jin, W., Xu, N. (2007). Organic-inorganic composite membranes prepared by self-assembly of polyelectrolyte multilayers on macroporous ceramic supports. J. Membr. Sci., 302, 78-86. 

Finally I will call attention to novel composite microstructures from lipids and minerals. When a-hydroxy fatty acid galactocerebroside and a mixture of anioic sulfated galactocerebrosides are suspended in ethylene glycol multilayer tubules are produced. When the tubule suspension is then treated with an acidic ferric chloride solution, the tubules became covered with shards of the mineral lepidocrocite (y-FeOOH).43 Although the direct application of this organic-inorganic composite is still uncertain, but it seems to have a possibility of designing new materials. 

Recently, we (82) and others (82-84) have shown that similar hetero-structures can be prepared by using two-dimensional inorganic sheets (made by exfoliation of various lamellar solids) in place of the organic polyanion. This technique offers a potentially powerful alternative to the construction of multi-component electron transfer systems, because it can, in principle, be used to stack up an arbitrary number of redox-active polymers without interpenetration (85). This chapter describes the preparation and photochemistry of simple multilayer composites on high-surface-area silica. Specifically, the synthesis and electron transfer kinetics of systems containing a polycationic sensitizer, poly-[Ru(bpy)2(vbpy)(Cl)2] (1), (abbreviated [Ru(bpy)3 ]n bpy = 2,2 -bipytidine and vbpy = 4-vinyl-4 -methyl-2,2 -bipyridine), and an electron-acceptor polycation poly[(styrene-co-]V-vinylbenzyl-N -methyl-4,4 -bipyridine)(Cl)2] (2), (PS-MV ) are presented. Using a solution-phase electron donor, 3, as the third electroactive component, it was possible to prepare and study the photoinduced electron transfer reactions of several different diad and triad combinations. 

Nanocomposites are made from two or more solid-phase materials, with at least one dimension in nanometers (1-100 nm). The solid phase can be amorphous, semicrystalline, grain, or a combination. The solid phase can also be organic, inorganic, or a combination. According to the size of the solid phase, nanocomposites generally include the following three types nanoparticles and nanopartide compounds (0-0 composites), nanoparticles and conventional bulk composites (0-3 composites), and composite nano films (0-2 composites). In addition, the nanolayered structure material is referred to as nanomaterial, and the multilayer nanocomposite made of different materials is also known as nanocomposite. 

A novel organic (chitosan) and inorganic (tetraethyl orthosilicate) composite membrane has been prepared, which is pH sensitive and drug permeable [258]. The latter possibly involved in ionic interactions. By plasma source ion implantation technique, the adhesion between linear low-density polyethylene and chitosan could be improved [259]. Such bilayer films showed 10 times lower oxygen permeability, a property of use in food packaging applications. These multilayer films were easily recyclable. 

Depending on the nature of the components used (layered silicate, organic cation, and polymer matrix) and the preparation method, three types of hybrid PCNs can be obtained [17]. Phase-separated microcomposites (conventional composites) are obtained when the polymer chains are unable to intercalate within the inorganic sheets clay lamellae remain stacked in structures marked as tactoids as in the pristine mineral. Otherwise, when the polymer chains penetrate in between the clay galleries, an intercalative system is obtained. In this case, the nanocomposite shows, at least in principle, a well-ordered multilayer morphology built up with alternating polymeric and clay layers. When clay platelets are randomly dispersed in the polymer matrix and the lamellae are far apart from each other, so that the periodicity of this platelet arrangement is totally lost, an exfoliated structure is achieved. 

Ceramic substrates are typically composites of crystalline and noncrystalline phases. The composition of the substrate is, of course, a function of the inorganic (and organic) components incorporated as raw materials. Alumina multilayer ceramics are produced from mixfures of powders with controlled purity, homogeneity, surface and bulk chemisfry and crysfallography, particle size and particle size distribution, surface area and morphology, including agglomeration [16]. 

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