Composite materials: organic-inorganic

Binsu VV, Nagarale RK, Shahi VK (2005) Phosphonic acid functionalized aminopropyl triethoxysilane-PVA composite material organic-inorganic hybrid proton-exchange membranes in aqueous media. J Mater (Them 15 4823 831... 

This generalization is useful, especially when other types of inorganic-organic interactions are considered. This mechanism is also suitable for the formation of nonsilicon mesoporous materials. The success of the cooperative templating model was illustrated by the diverse compositions of organic-inorganic mesostructures found to be possible. 

In any case, it is clear that, for its own nature, sol-gel material is suitable for the formation of many different composite materials [207] inorganic and organic polymers, as well as many different kinds of nano-objects possessing effective electrocatalytic properties, can find stable inclusion into a host matrix possessing all the characteristics previously listed. The most simple approach consists of adding the filler to the siliceous matrix after sol-gel formation. However, composite materials can also be obtained by synthesizing the sol-gel film in the presence of the precursor of the filler, e.g., a monomer [227] or a metal complex [228]. The synthesis of the composite material is finalized in a subsequent step, e.g. by a chemical oxidation or reduction, leading to polymer chains or metal nanoparticles, respectively, included inside the sol-gel matrix. 

The new class of polymer materials, organic- inorganic (clay) nanocomposites, was also reported as an excellent FR composition [234]. Nylon-6 clay nanocomposites, first developed by Toyota Central Research and Development Laboratories, are materials with unique properties. The nylon- 6 clay nanocomposites (clay mass fraction from 2%-70%) are synthesized by ring - opening polymerization of e-caprolactam in the presence of cation exchanged montmorillonite clay [235]. 

Schmidt, H. and Krug, H. (1994) Sol-gel-based inorganic organic composite materials, in Inorganic and Orgartometallic Polymers II Advanced Materials and Intermediates (eds P. Wisian-Neilson, H.R. Allcock, and K.J. Wynne), American Chemical Society, Washington, DC,... 

Other specific applications are presented in the book published by L.C.Klein [KLE 94] like micro lenses, composite layers (organic-inorganic) etc., as well as optical applications of massif sol-gel materials. 

Finally, the combined reinforcing effect and high absorption capacity of asbestos fibers have been exploited in a variety of appHcations to increase dimensional stabiHty, typically in vinyl or asphalt tiles and asphalt toad surfacing. Figure 9 summarizes, as of 1984, the various classes of application for asbestos fibers in combination with other materials. The diagram shows that in recent years, most industrial appHcations have evolved towards composite materials where the fibers are bonded within an organic or inorganic matrix. 

Sohd rocket propellants represent a very special case of a particulate composite ia which inorganic propellant particles, about 75% by volume, are bound ia an organic matrix such as polyurethane. An essential requirement is that the composite be uniform to promote a steady burning reaction (1). Further examples of particulate composites are those with metal matrices and iaclude cermets, which consist of ceramic particles ia a metal matrix, and dispersion hardened alloys, ia which the particles may be metal oxides or intermetallic compounds with smaller diameters and lower volume fractions than those ia cermets (1). The general nature of particulate reinforcement is such that the resulting composite material is macroscopicaHy isotropic. 

Molecular hybrids between organic polymers and silica gel are expected to show many possibilities as new composite materials. First, the hybrids may show intermediate properties between plastics and glasses (ceramics). In addition, the composition of the hybrids can be widely varied. In other words, the hybrids can be used to modify the organic polymer materials or to modify the inorganic glassy materials. The hydrophilic modification as described before is a typical example. 

Similarly, a composite of hydroxyapatite and a network formed via cross-linking of chitosan and gelatin with glutaraldehyde was developed by Yin et al. [ 169]. A porous material, with similar organic-inorganic constituents to that of natural bone, was made by the sol-gel method. The presence of hydroxyapatite did not retard the formation of the chitosan-gelatin network. On the other hand, the polymer matrix had hardly any influence on the high crystallinity of hydroxyapatite. 

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