Transparent materials nanocomposites

Transparent materials nanocomposites with high refractive index (w 1.65-1.79) and high transparence in visible light region, with transmittance higher than 90%, are potential materials for fabrication of optical fibers, waveguides, lenses, and LED packages [7]. 

Dispersion of nanosilica within the mbber matrices usually generates optically transparent materials. All the ACM-silica and ENR-sihca hybrid composites are completely transparent up to 50 wt% of TEOS concentrations. EoUowing are the figures (Figure 3.9) which show the visual appearance of the representative hybrid nanocomposites. The logos over which the films (average film thickness 0.25 mm) are placed are clearly visible. 

Kim et al. studied the effect of bacterial cellulose on the transparency of PLA/bacterial nanocomposites, since bacterial cellulose had shown good potential as reinforcement or preparing optically transparent materials due to its structure, which consists of ribbon-shaped fibrils with diameters in the range from 10 to 50 nm. They found that light transmission of the PLA/bacterial cellulose nanocomposite was quite high due to the size effect of... 

Shams, M.I., Ifuku, S., Nogi, M., Oku, T., Yano, H., 2011. Fabrication of optically transparent chitin nanocomposites. Applied Physics A—Materials Science Processing 102, 325-331. 

But not only the dimensions and the concentration is enough to obtain an optically transparent material. The morphology and the aggregation of inorganic particles can influence the optical properties of nanocomposites. Nanometric-sized particles compared to micron-sized particles have higher surface/volume ratio. When the particle size decreases, the percentage of molecules/atoms present on the surface is increased. For this reason, the interpartide interactions due to forces such as van der... 

Many nanocomposites prepared with different polymer matrix can show good low haze. Wang et al. [16] elucidated that transparent rubber materials can be prepared if the rubber itself is a transparent material. In case of the cis-1,4 polybutadiene... 

Li, Y.Q., Fu, S.Y., Yang, Y, and MaL YW. (2008) Facile synthesis of highly transparent polymer nanocomposites by introduction of core-shell stmctured nanoparticles. Chemistry of Materials, 20, 2637-2643. 

I, H. Tseng, Y. F. Liao, J. C. Chiang, M. H. Tsai, Transparent polyimide/graphene oxide nanocomposite with improved moisture barrier property., Materials Chemistry and Physics, vol. 136, pp. 247-253, 2012. 

Yang, B., et al., Embedding graphene nanoparticles into poly (N, N -dimethylacrylamine) to prepare transparent nanocomposite films with high refractive index. Journal of Materials Chemistry, 2012. 22(39) p. 21218-21224. 

It has also been demonstrated that mesoporous materials are viable candidates for optical devices [90]. Silicon nanoclusters were formed inside optically transparent, free-standing, oriented mesoporous silica film by chemical vapor deposition (CVD) of disilane within the spatial confines of the channels. The resulting silicon-silica nanocomposite displayed bright visible photoluminescence and nanosecond lifetimes (Fig. 2.12). The presence of partially polymerized silica channel walls and the retention of the surfactant template within the channels afforded very mild 100-140°C CVD conditions for the formation of... 

Recent developments in the cross-polymerization of the organic components used in bicontinuous microemulsions ensure the successful formation of transparent nanostruc-tured materials. Current research into using polymerizable bicontinuous microemulsions as a one-pot process for producing functional membranes and inorganic/polymer nanocomposites is highlighted with examples. 

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],... 

Arabinogalactan is transparent both in UV and visible ranges, and electronic absorption spectroscopy can be successfully used to study arabinogalactan assisted nanoparticles. The absorption spectra of the silver and gold nanocomposites solutions have intensive absorption peaks at 420 and 524 nm, respectively (Fig. la), which proves the presence of silver and gold zero-valence metals [3]. The peaks are attributed to collective excitations of conduction electrons (plasmonic resonance). This fact is of interest for synthesis of water soluble highly efficient non-linear optical materials [1]. 

Two types of Cu-nanoparticles-in-dielectric nanocomposites were produced through hydrogen reduction of Cu(II) Cu-zeolite and Cu-zeolite-silica. Amorphous silica was prepared by the sol-gel technique and served as optically transparent matrix incorporating zeolite microcrystals, The copper nanoparticles provide an optical response of the composite material due to the plasmon resonance band varied due to changes of matrix features. 

In the present work, we consider the two approaches for synthesis of nanoparticles designed for metal particles and being in the progress for ultraflne semiconductors. They allow to fabricate nanocomposites of the type nanoparticles-in-dielectrics with amorphous and crystalline matrices. The first one is based on the sol-gel technique producing dielectric silica films with nanoparticles incorporated within silica matrix [1]. Nanoparticles provide an optical response of the material due to the plasmon resonance [2] with variable spectral position and band shape. In the second approach nanoparticles are produced within the crystalline zeolite matrices which stabilize both the few-atomic clusters (e.g., Agg) and metal particles in the size range of 1-20 nm [3], Chemical routes of their synthesis admit easy control of size and optical properties. The metal nanoparticles in zeolites can be transformed into semiconductors without destroy of the zeolite matrix and with incorporation of zeolite microcrystals into transparent silica films. This construction... 

---