Nanolayered composites

On annealing the PC/PET micro- and nanolayered composites, the PET iayers were found to undergo coid crystallization and to form lamellar crystals independent of the thickness of individual layers see Fig. 9.6. Due to the physical confinement imposed by the adjacent PC layers, the PET layers (and in general semicrystalUne polymers) are unable to develop well-defined spherulitic structures, as in bulk melt-crystaUized samples [8,13]. 

A. Misra, MJ. Demkowicz, X. Zhang, R.G. Hoagland, The radiation damage tolerance of ultra-high strength nanolayered composites, JOM 59 (2007) 62—65. 

Nanolayer coatings Nanolithography Nanomaterials Nanometer composites Nanoparticles Nanostrip Nanotechnology Nantokite [14708-85-1] Nantokite [14708-8517] NaOH... 

Firstly it can be used for obtaining layers with a thickness of several mono-layers to introduce and to distribute uniformly very low amounts of admixtures. This may be important for the surface of sorption and catalytic, polymeric, metal, composition and other materials. Secondly, the production of relatively thick layers, on the order of tens of nm. In this case a thickness of nanolayers is controlled with an accuracy of one monolayer. This can be important in the optimization of layer composition and thickness (for example when kernel pigments and fillers are produced). Thirdly the ML method can be used to influence the matrix surface and nanolayer phase transformation in core-shell systems. It can be used for example for intensification of chemical solid reactions, and in sintering of ceramic powders. Fourthly, the ML method can be used for the formation of multicomponent mono- and nanolayers to create surface nanostructures with uniformly varied thicknesses (for example optical applications), or with synergistic properties (for example flame retardants), or with a combination of various functions (polyfunctional coatings). Nanoelectronics can also utilize multicomponent mono- and nanolayers. 

The investigated samples are thin film multilayer nanostructures [3-6]. Each structure unit is a nanolayer wdth a locally distributed nanociystal array inside it. The geometry of the nanostructures can be tuned by controlling the thicknesses and the arranging of the sensitizing and complementary, buffer or matrice, components. Every nanolayer can be designed as one material, as composition of nanocrystals, of clusters of two materials [3-5]. 

Examples of the use of nanostructured materials for packaging applications have been given in Chaudhry et al. (2008) and references therein. One of the first market entries into the food packaging arena was polymer composites containing clay nanoparticles (montmorillonite). The natural nanolayer structure of the clay particles impart improved barrier properties to the clay-polymer composite material. Some of the polymers which have been used in these composites for production of packaging bottles and films include polyamides, polyethylene vinyl acetate, epoxy resins, nylons, and polyethylene terephthalate. 

The term polymer clay nanocomposite (PCN) refers to a material composed of two-phase materials, where one phase (clay) is dispersed in the second phase (polymer matrix) at a nanometer level. Composites exhibiting structural and compositional changes at the molecular scale have demonstrated several physical property enhancements that are otherwise unavailable in conventional composites. Of these, layered silicates have proven themselves vital as a reinforcing agent when dispersed into engineering plastics. Nanolayers, however, are extremely difficult to disperse in polymer matrices because of their tendency for face-to-face... 

Sodium montmorillonite/PVK composites have been prepared by free radical polymerization using cerium ammonium nitrate [223]. Sodium montmo-rillonite was used in the form of nanolayers both of hydrophilic and organophilic types, modified with octadecylamine and trimethyl stearyl ammonium. 

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