Nanocomposites optical properties

The branched polysaccharide dextran is assembled with alkanethiol-modified gold nanoparticles and the resulting nanocomposite is then functionalized to facilitate the specific binding of target biomolecules. This biorecognition process can be easily detected by particle plasmon resonance (PPR), based on the optical properties of gold nanoparticles [163]. 

Fig. 1.12 (A) Increase in surface plasmon ab- and from mixtures with lower chitosan concen-sorptionasAu nanoparticles are produced from a tration (ii) or lower HAuCI4 amount (iii) six reaction mixture containing 1 % chitosan, 1 % different self-sustained nanocomposite films acetic acid and 0.01 % tetrachloroauric (III) acid showing the control over the optical properties. (HAuCU) (B) shiftofsurface plasmon absorption Reprinted with permission from [164], 2004, for films prepared from the previous mixture (i), American Chemical Society.

Sanchez, C., Lebeau, B., Chaput, F. and Boilot, J.P. (2003) Optical properties of functional hybrid organic-inorganic nanocomposites. Advanced Materials, 15, 1969-1994. 

The remaining sections outline recent findings on the optical properties of metal-dendrimer nano-composites. The sections have been organized into areas of interest related to the fabrication as well as photophysical properties of these new and important materials. The first section discusses some of the important issues concerning the fabrication of these novel materials and their chemical characterization. The second section discusses the linear and nonlinear optical properties of these materials. The third section provides details related to the ultrafast emission properties of gold- and silver-dendrimer nanocomposites. 

LINEAR AND NONLINEAR OPTICAL PROPERTIES IN METAL-DENDRIMER NANOCOMPOSITES... 

While the linear absorption and nonlinear optical properties of certain dendrimer nanocomposites have evolved substantially and show strong potential for future applications, the physical processes governing the emission properties in these systems is a subject of recent high interest. It is still not completely understood how emission in metal nanocomposites originates and how this relates to their (CW) optical spectra. As stated above, the emission properties in bulk metals are very weak. However, there are some processes associated with a small particle size (such as local field enhancement [108], surface effects [29], quantum confinement [109]) which could lead in general to the enhancement of the fluorescence efficiency as compared to bulk metal and make the fluorescence signal well detectable [110, 111]. 

Highly structured, 3-D nanoparticle-polymer nanocomposites possess unique magnetic, electronic, and optical properties that differ from individual entities, providing new systems for the creation of nanodevices and biosensors (Murray et al. 2000 Shipway et al. 2000). The choice of assembly interactions is a key issue in order to obtain complete control over the thermodynamics of the assembled system. The introduction of reversible hydrogen bonding and flexible linear polymers into the bricks and mortar concept gave rise to system formation in near-equilibrium conditions, providing well-defined stmctures. 

Goodson,T., et al. (2004), Optical properties and applications of dendrimer-metal nanocomposites, Int. Rev. Phys. Chem., 23,1. 

OPTICAL PROPERTIES OF RIGID PVC/ MONTMORILLONITE NANOCOMPOSITES WITH EPOXY RESIN AS COMPATIBILIZER... 

Polyvinyl chloride/montmorillonite nanocomposites were prepared using an epoxy resin, as compatibiliser, and the effect of this compatibiliser on the optical properties of the nanocomposites investigated. It was found that the transparency of the nanocomposites improved with increasing content of montmorillonite, which was pretreated with the epoxy resin. The good transparency of the nanocomposites also indicated that the epoxy resin improved the processing stability of the nanocomposites. 3 refs. 

Sipe JE, Boyd RW (2002) Nanocomposite materials for nonlinear optics based on local field effects, in optical properties of nanostructured random media, 82nd edn. Springer, Berlin, pp 1-19... 

These few examples show how the use of nanocomposite systems with hetero polysiloxane type of matrices leads to interesting properties for applications. Further developments using these basic systems are transparent controlled release coatings for anti-fogging systems [41], anti-corrosive systems for metal protection [42], and nanocomposite optical bulk materials [43],... 

It is evident that the incorporation of POSS cages into polymeric materials often results in substantial improvements in polymer properties and offer the possibility to control the mechanical, chemical and physical properties of the system during polymerization as well. Intense efforts have recently been directed toward the development of new porous materials because of their utihty and potential utihty as catalysts and catalyst supports [208,209], dielectric materials for electronic appHcations [210], media for optical [211] and sensor [212] applications, and selectively permeabihty membranes [213] and precursors [10] for POSS nanocomposites. Significant property enhancements imparted by the inclusion of a nanosized inorganic... 

Intercalation of electroactive polymers such as polyaniline and polypyrrole in mica-type layered silicates leads to metal-insulator nanocomposites. The conductivity of these nanocomposites in the form of films is highly anisotropic, with the in-plane conductivity 10 to 10 times higher than the conductivity in the direction perpendicular to the film. Conductive polymer/oxide bronze nanocomposites have been prepared by intercalating polythiophene in V2O5 layered phase, which is analogous to clays. °° Studies of these composites are expected not only to provide a fundamental understanding of the conduction mechanism in the polymers, but also to lead to diverse electrical and optical properties. 

Hydrodynamic and optical properties of polymers [NP(OR)2]n [R = CH2CF3, CH2(CF2)2H, CH2(CF2)4H] have been analysed. Mechanical properties of polyphosphazene-silicate nanocomposites, prepared from (NP[(0CH2CH2)20Me]2 n (MEEP) and tetraethoxysilane, have been investigated as function of the catalyst used. ... 

Size monitoring and design of optical properties of nanocomposites... 

The new water soluble highly stable metal-polysaccharide nanocomposites of noble metals have been fabricated within the framework of the new approach to the synthesis of hybrid nanosized materials on the basis of arabinogalactan. Distinctive optical properties of the nanoparticles are demonstrated as the plasmonic resonance. Nanobiocomposites with target optical characteristics have a great potential to design promising multifunctional materials with controlled optical properties as well as new optical systems and optical markers in medicine. 

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