Polymer nanocomposite development

Goettler, L. A., Lee, K. Y., and Thakkar, H. 2007. Layered silicate reinforced polymer nanocomposites Development and applications. Polymer Reviews 47 291-317. 

L.A. Goettler, K.Y. Lee, H. Thakkar, Layered silicate reinforced polymer nanocomposites development and applications, Polymer Reviews 47 (2) (2007) 291-317. 

Polymer nanocomposite development has been a sensitive area of research and has evolved significantly over the last two decades because of the ability of nanoscale reinforcements to create remarkable... 

As mentioned above, the new method of cryochemical synthesis of polymer nanocomposite films has been developed based on co-deposition of M/ SC and monomer vapors at temperature 80K and subsequent low-temperature solid-state polymerization of monomer matrix ([2] and works cited herein). It has been established that a number of monomers (acrylonitrile, formaldehyde, /i-xylylene and its derivatives) polymerize in solid state in absence of thermal movement of molecules owing to own specific supra-molecular structure. When reaction is initiated by y- or UV-radiation the formation of a polymer matrix occurs even at the temperatures close to temperature of liquid helium [66-69]. 

This work has demonstrated that we have been successful in extruding fibers from these polymer nanocomposites, knit them into textiles, and test their flammability. These prototype nanocomposite FR fiber-forming polymers and textile materials based upon them could be taken forward by interested parties for scale-up and commercial development. 

Two specific imaging modes developed in combining ESEM (environmental scanning electron microscopy) and STEM and developed in the MATEIS laboratory can be useful for the characterization of CNT and CNT polymer nanocomposites. 

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. 

This type of cross-polymerization of all of the organic components (hke MMA, HEMA and a polymerizable surfactant) in a bicontinuous microemulsion is an important area of recent development in microemulsion polymerization, which can be used to produce nanostructures of transparent polymer solids. The polymerization can be readily initiated using either redox or photo-initiators. The gel formation usually occurred within 20 minutes. The use of this novel type of microemulsion polymerization for preparing transparent inorganic-polymer nanocomposites in the form of films or sheets is emerging and exciting. However, very little pubhshed information about this type of nanocomposite is available, as will be described in the following sections. 

The electrical conductance of carbon nanotubes is sensitive to the chemical environment of the tubes. A large difference in the electrical conductance is observed for the carbon nanotubes in the presence of air and oxygen atmosphere. " " It is possible to tune the electrical conductance of carbon nantubes reversibly using adsorbent gas molecules. The carbon nanotubes were also used to increase the conductance of a conjugated polymer for the development of electroluminescence polymer-nanocomposites. " ... 

The y-ray irradiation synthesis method, which can be carried out at ambient temperature and pressure in aqueous or non-aqueous solutions, has been developed to prepare nanomaterials of metals, alloys, elemental chalcogens, chalcoge-nide semiconductors and inorganic/polymer nanocomposites. 

In terms of nanocomposite reinforcement of thermoplastic starch polymers there has been many exciting new developments. Dufresne [62] and Angles [63] highlight work on the use of microcrystalline whiskers of starch and cellulose as reinforcement in thermoplastic starch polymer and synthetic polymer nanocomposites. They find excellent enhancement of properties, probably due to transcrystallisation processes at the matrix/fibre interface. McGlashan [64] examine the use of nanoscale montmorillonite into thermoplastic starch/polyester blends and find excellent improvements in film blowability and tensile properties. Perhaps surprisingly McGlashan [64] also found an improvement in the clarity of the thermoplastic starch based blown films with nanocomposite addition which was attributed to disruption of large crystals. 

Varying the polymer type and characteristics allows development of sophisticated metal-polymer nanocomposites with tunable properties and promise for future apphcations. Yet, one can expect vigorous development of this field for years to come so that new polymeric systems yielding better control over nanoparticle formation and properties will be designed. 

A limited number of methods have been developed for the preparation of metal-polymer nanocomposites. Usually, such techniques consist of highly specific approaches, which can be classified as in situ and ex situ methods. In the in situ methods, two steps are needed First, the monomer is polymerized in solution, with metal ions introduced before or after polymerization. Then metal ions in the polymer matrix are reduced chemically, thermally, or by UV irradiation. In the ex situ processes, the metal nanoparticles are chemically synthesized, and their surface is organically passivated. The derivatized nanoparticles are dispersed into a polymer solution or liquid monomer that is then polymerized. 

A nanocomposite material can be defined as one that consists of two or more different material components, at least one of which has a domension (i.e., length, width, or thickness) below 100 nm. There are many types of nanocomposites presently under research and development including polymer/inor-ganic particle, polymer/polymer, metal/ceramic, and inorganic-based nanocomposites. However, the first named one, commonly called polymer nanocomposite (PNC) and defined as the comhination of a polymer matrix resin (continuous phase) and inclusions having at least one dimension less than 100 nm, is the only type of nanocomposite to date that has seen any significant commercial activity. 

As the adduced above data have shown, the polymer nanocomposites with three main types of inorganic nanofiller and also polymer-polymeric nanocomposites melt viscosity caimot be described adequately within the fiamework of models, developed for the description of microcomposites melt viscosity. This task can be solved successfully within the framework of the fractal model of viscous liquid flow, if in it the used nanofiller special feature is taken into account correctly. Let us note that unlike microcomposites nanofiller cotents enhancement does not result in melt viscosity increase, but, on the contrary, reduces it. It is obvious, that this aspect is very important from the practical point of view. 

Rajesh, T. Abuja, and D. Kumar, Recent progress in the development of nano-structured conducting polymers/nanocomposites for sensor applications, Sens. Actuators B, 136, 275-286 (2009). 

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