Subject nanocomposites properties

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]. 

The most-popular nanofiller is a natural layered silicate, montmorillonite, that is subjected to specific treatments. The properties of the final nanocomposite depend on the these treatments and the mixing efficiency. 

Historically, polysiloxane elastomers have been reinforced with micron scale particles such as amorphous inorganic silica to form polysiloxane microcomposites. However, with the continued growth of new fields such as soft nanolithography, flexible polymer electronics and biomedical implant technology, there is an ever increasing demand for polysiloxane materials with better defined, improved and novel physical, chemical and mechanical properties. In line with these trends, researchers have turned towards the development of polysiloxane nanocomposites systems which incorporate a heterogeneous second phase on the nanometer scale. Over the last decade, there has been much interest in polymeric nanocomposite materials and the reader is directed towards the reviews by Alexandre and Dubois (4) or Joshi and Bhupendra (5) on the subject. 

Polymer clay nanocomposites have, for some time now, been the subject of extensive research into improving the properties of various matrices and clay types. It has been shown repeatedly that with the addition of organically modified clay to a polymer matrix, either in-situ (1) or by melt compounding (2), exfoliation of the clay platelets leads to vast improvements in fire retardation (2), gas barrier (4) and mechanical properties (5, 6) of nanocomposite materials, without significant increases in density or brittleness (7). There have been some studies on the effect of clay modification and melt processing conditions on the exfoliation in these nanocomposites as well as various studies focusing on their crystallisation behaviour (7-10). Polyamide-6 (PA-6)/montmorillonite (MMT) nanocomposites are the most widely studied polymer/clay system, however a systematic study relating the structure of the clay modification cation to the properties of the composite has yet to be reported. 

Preparation of polymer nanocomposites is nowadays an important research subject since polymer properties can be enhanced (e.g., modulus, strength, thermal resistance, per-meabifity, flammabifity resistance, and even biodegradability)... 

There are reports that ethylene and 1-octane have been copolymerized using a similar catalyst, and that the physical properties of this copolymer were compared with those of a nanocomposite fabricated using the dry-compound method [41]. A case is also reported in which polyethylene was subjected to in-situ polymerization. 

AyatoUahi, M. R., Shadlou, S., and Shokrieh, M. M., Multiscale modeling for mechanical properties of carbon nanotube reinforced nanocomposites subjected to different types of loading. Composite Structures, 93, 2250-2259 (2011). 

On the other hand carbon nanotubes (CNT) have been the subject of extensive investigation due to their remarkable properties such as very high aspect ratio, excellent mechanical, electrical, optical and magnetic properties. To exploit the properties of carbon nanotubes, efficient exfoliation of the CNT bundles in the polymer matrix is a prerequisite. There are various methods aimed at efficient exfoliation of CNT either in polymer or solvent [7-10]. In addition, nanocomposites... 

The fascinating properties exhibited by nanoparticles, such as blue shift of the absorption spectrum, size-dependent luminescence, etc., are various manifestations of the so-called quantum confinement effect. These unique properties make ZnO a promising candidate for applications in optical and optoelectronic devices [35-38]. Polymer-based nanocomposites are the subject of considerable research due to the possibility of combining the advantages of both polymers and nanoparticles. There are several applications of polymeric nanocomposites based on their optical, electrical and mechanical properties. Further, nanocrystals dispersed in suitable solid hosts can be stabilized for long periods of time. Polystyrene (PS)— an amorphous, optically clear thermoplastic material, which is flexible in thin-film form—is often chosen as a host matrix because of its ideal properties for investigating optical properties. It is one of the most extensively used plastic materials, e.g., in disposable cutlery, plastic models, CD and DVD cases, and smoke-detector housings. 

The relationship between microstructure and physical properties of ternary nanocomposites has been the subject of intense investigation due to their very complex nature. In this section, the mechanical properties of polymer blend nanocomposites are reviewed in the context of their microstructure. Following this, the various strategies that have been employed to obtain improved filler dispersion and interfacial interactions are mentioned. 

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