Nanocomposites dendrimers

Fig. 10 pH-Dependent permeability of the anions Fe(CN)6 and the cation Ru(NH3)g in nanocomposite dendrimer-poly(maleic anhydride) grafts that contain - CO2H/ - C02" and NH2/-NH3 groups in the film with a anion permeability at low pH where the... 

Polymer-Clay Nanocomposites Dendrimers and Other Dendritic Polymers... 

It is impossible to give an overview of every nanoparticle class in one chapter, thus we will limit our discussion to an important and more cohesive field, dendrimer nanocomposites. Dendrimer composite nanoparticles (or Composite Nanodevices - CNDs) are nanosized organic-inorganic hybrid particles made from dendrimer templates that contain small clusters of inorganic nanomaterials of interest entrapped in the network of the macromolecular templates. The resulting composite nanoparticles display the chemical and physical properties both of the inorganic molecules/atoms/clusters and their template. 

Thus, supermolecular liquid crystals with a cyclotriphosphazene dendritic core and polycatenar mesogenic units (144) were obtained in three steps by the conventional sequence of substitution (i), derivatization (ii and iii) methods from [N3P3CI6] (Scheme 9). Due to the microsegregation of the alkyl chains and the aromatic central cores and the space-filling properties, compounds (144) adopt a discotic conformation assembled in a columnar mesophase and illustrate the possibilities of using cyclotriphosphazenes for the design of columnar assemblies at room temperature, in the mesophase or in a vitrified solid state with interest for applications in material science. Similarly, the new family of solution processable, photoluminescent, monodisperse nanocomposite dendrimers (145) (Tg > 165 °C, > 465 °C)... 

There is currently considerable interest in processing polymeric composite materials filled with nanosized rigid particles. This class of material called "nanocomposites" describes two-phase materials where one of the phases has at least one dimension lower than 100 nm [13]. Because the building blocks of nanocomposites are of nanoscale, they have an enormous interface area. Due to this there are a lot of interfaces between two intermixed phases compared to usual microcomposites. In addition to this, the mean distance between the particles is also smaller due to their small size which favors filler-filler interactions [14]. Nanomaterials not only include metallic, bimetallic and metal oxide but also polymeric nanoparticles as well as advanced materials like carbon nanotubes and dendrimers. However considering environmetal hazards, research has been focused on various means which form the basis of green nanotechnology. 

Biphasic catalysis in an organic/fluorous solvent system by Pd/dendrimer nanocomposites. 

Wang, Y., Angelatos, A.S. and Caruso, F. (2008) Chemistry of Materials, 20,848-858. Sukhorukov, G.B. (2002) (eds R. Arshady, and A. Guyot), Microspheres, Microcapsules and Liposomes, Vol. 5 Dendrimers, Assemblies and Nanocomposites, Citus Books, London, Author are the amended details correct ... 

Varnavski, O., Ispasoiu, R.G., Balogh, L., Tomalia, D., and Goodson, T. (2001) Ultrafast time-resolved photoluminescence from novel metal-dendrimer nanocomposites./. Chem. Phys. 114, 1962-1965. 

UV-Vis spectroscopy has been utilized to characterize the amount of copper(II) ions bound inside PAMAM dendrimers, as well as the size of resulting Cu nanocomposites upon chemical reduction [44-46]. This work has been reviewed extensively by Balogh and Tomalia [50],... 

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. 

With precise functionalization, it is possible to prepare different types of dendrimer nanocomposite topologies. Balogh and Tomalia have utilized the functionalization of PAMAM dendrimers to create both external and internal... 

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

Figure 21.1 A-Structure of the host PAPAM dendrimer. B-Fabrication procedure for metal-dendrimer nanocomposites. C- Pd and Pt dendrimer encapsulated nanoparticles prepared by displacement reactions [66]. D, E -External and internal dendrimer nanocomposite topologies, respectively [70,77],...

The linear absorption of dendrimer nanocomposite thin films has also shown... 

Figure 21.2 Absorption spectrum for the gold-dendrimer nanocomposite. Inset absorption spectrum for PAMAM dendrimer (generation 5).

Understanding the mechanisms of the optical limiting effect in metal dendrimer nanocomposites may also require understanding the timescale of the effect. In general, for optical excitation close to the linear absorption band, such... 

Indeed, the timescale of the optical limiting effect in dendrimer nanocomposites is somewhat different than that found in other materials and this may be crucial to the understanding of the mechanism. Recent reports have investigated... 

Figure 21.3 Nonlinear transmission of silver -dendrimer nanocomposites Ag(0) E at 532 nm. Pulse repetition rate- 10 Hz. Inset nonlinear transmission results for Ag(0) E in a concentration of 2.95x 10 4 mole/kg at 532 nm, with the variation of the pulse repetition rate t indicates the specific repetition periods.

PHOTO-LUMINESCENCE PROPERTIES OF DENDRIMER METAL NANOCOMPOSITES... 

---