Preparation of Nanocomposite

A variety of more complicated compounds having a CH2CH2 linkage to the POSS core have been prepared using methods outlined in Table 29. Thus, epoxides have been made from cyclohexene-terminated POSS (Table 29, entries 1 and 2) and are precursors for the preparation of nanocomposite polymers under ultraviolet irradiation (Figure 43). ... 

FIGURE 3. The sol-gel approach to the preparation of nanocomposite materials (a) starting mixture and (b) after gelation and drying... 

Besides metal ions and hydrogen ions, other cationic substances (e.g., cationic organic molecules or cationic tensides) can also be exchanged in the external and internal surfaces. Cationic tensides can make the surface hydrophobic (Lagaly and Dekany 2005). Furthermore, the distance between the layers is widened, enabling polymer chains to move in. This is an important condition in the preparation of nanocomposites containing layer silicates. Recently, the production and application of nanocomposites has become widespread, and many papers have been presented in this field (e.g., Paiva et al. 2008 Pavlidoua and Papaspyrides 2008). 

PVA was widely used as a matrix for preparation of nanocomposites due to its easy processability, high clarity and biocompatibility. Ag-PVA nanocomposites were prepared by reduction of Ag" ions in PVA aqueous solutions using gamma irradiation followed by solvent evaporation. Ag-PVA hydrogel nanocomposite was obtained by simultaneous reduction of Ag" and cross-linking of PVA by yirradiation. 

Journal of Materials Science 38, No. 10,15th May 2003, p.2143-7 PREPARATION OF NANOCOMPOSITE FIBERS FOR PERMANENT ANTIBACTERIAL EFFECT... 

In addition to the above-mentioned conventional polymers, several interesting developments have taken place in the preparation of nanocomposites of MMT with some specialty polymers including the N-heterocyclic polymers like poly (N-vinylcarbazole) (PNVC) [32, 33], polypyrrole (PPY) [34, 35], and polyaromatics such as polyaniline (PANI) [36-38]. PNVC is well known for its high thermal stability [39] and characteristic optoelectronic properties [40-43]. PPY and PANI are known to display electric conductivity [44-46]. Naturally, composites based on these polymers should be expected to lead to novel materials [47,48]. 

Preparation of nanocomposites using the slurry compounding process has been carried out with Nylon and epoxy resins. In Reference 91, this method is implemented... 

Nanocomposites are materials in which nanoparticles (in this case, nanorods) are dispersed in a continuous matrix. The matrix may be a polymer, nanorods, or other nanoparticles. Nanorod composites find applications in diverse areas such as efficient charge storage, removal of contaminants (e.g. surfactant) from water, emissivity control devices, and metallodielectrics, and so on. A number of methods such as electroless deposition, the sol-gel method, the hydrothermal method, solution casting, carbother-mal reduction, the template-based method, the sonochemical method, and electrospinning can be used to prepare composite nanorods. Nanorod composites are different from core-shell nanorods. In core-shell nanorods, the coating is uniform, whereas in the nanorod composite (consisting of a nanorod and a nanoparticle on a surface), fine nanoparticles are dispersed on the surface of the nanorods. Some specific examples of the preparation of nanocomposites consisting of nanorods are described below. 

Nanocomposite aerogels mainly consist as homogeneous dispersions of nanoparticles in an aerogel matrix. The preparation of nanocomposite aerogels can be... 

The nanoporous hypercrosslinked polystyrene proves to be the material of choice for the preparation of nanocomposites (Chapter 17) by formation of nano-sized clusters of catalyticaUy active metals, for example, platinum or palladium, or of magnetic nano-crystals of iron oxides. Being confined in the nano-cage, the clusters do not agglomerate so that the catalysts remain stable and highly active in any liquid media. 

F. Wypych, N. Seefeld, and I. Denicolo, Preparation of nanocomposites based on the encapsulation of conducting polymers into 2H-M0S2 and lT-TiS2, Quimica Nova, 20, 356-360 (1997). 

The preparation of nanocomposite materials by thermolysis of mercaptide molecules dissolved in polymer represents quite a universal approach, and this reaction scheme is limited only by the ability to synthesize the mercaptide precursor. A short description of the most common mercaptide preparation routes follows. 

Variations in the preparation of nanocomposites have now been investigated extensively. Liu et al. [202] proposed the preparation of nylon-6/clay nanocomposites by a melt-intercalation process. They reported that the crystal structure and crystallization behaviors of the nanocomposites were different from those of nylon-6. The properties of the nanocomposites were superior to nylon-6 in terms of the heat-distortion temperature, strength, and modulus without sacrificing their impact strength. This is attributed to the nanoscale effects and the strong interaction between the nylon-6 matrix and the clay interface. More recently, nanocomposites of nylon-10,10 and clay were prepared by melt intercalation using a twin-screw extruder [203]. The mechanical properties of the nanocomposites were better than those of the pure nylon-10,10. 

The preparation of nanocomposite membranes by intra-membrane growth within a proton exchange membrane was first described by Mauritz et al. [45-47]. The then novelty of this approach and the breadth and depth of these studies warrant the following discussion of the results, which in many ways laid the foundation for future work in this area. This group made use of the hydrophilic ionic cluster regions of Nafion for confined, sulfonic acid group catalysed, hydrolysis/condensation reactions of impregnated alkoxides. Nafion membranes were first swollen in ethanol/water, then tetraethoxy-silane (or aluminium, titanium and zirconium alkoxides) permeated from one side of the membrane. In addition to the concentration profile of in-... 

There have been a number of studies dedicated to organically modified layered silicate reinforced completely biodegradable nanocomposites to target highly exfoliated structures. Renewable resources-based biodegradable polymers utilized so far for the preparation of nanocomposites are poly(lactic acid) (PLA) [40-68,11-15], poly(3-hydroxy butyrate) (PHB) [69,16-20] thermoplastic starch [71-77,21-25], plant oils [78-81,26-30], cellulose [82,83,30,31], etc. The following section deals with the transformation of the properties of renewable sources-based biodegradable polymers as their layered silicate nanocomposites. 

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