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Nanocomposites are man-made materials that enhance performance in various applications, including structural, functional, and cosmetic. They consist of a base medium combined with suspended nanoparticles, which are much smaller than those in regular composites. The smaller the particle size, the greater the surface area available for interaction, and the greater the potential to affect material properties. Nanocomposites have numerous applications, including electronics, optics, and biomedical.
A nanocomposite is a man-made material designed to enhance performance in any number of unique applications: structural, functional, or cosmetic. As with other composites, the nanocomposite includes a base medium, or matrix, composed of plastic, metal, or ceramic combined with suspended nanoparticles. The filler particles are much smaller than those of normal composites and are the size of large molecules, at least a hundred times smaller than the nucleus of a human egg cell.
The solid base medium of a nanocomposite begins as a liquid that can be sprayed onto a surface, extruded, or injected into a mold. Filler particles work according to their shape: round, like a ball, or long and thin, like a tube. Fullerenes, nanoparticles composed entirely of carbon atoms like buckyballs or nanotubes, are orders of magnitude smaller than the carbon fibers or bead fillers found in regular composites. These fullerenes can carry any number of reactive molecules used in medicinal applications.
The smaller the particle size of the filler suspended within the base medium, the greater the surface area available for interaction, and the greater the potential to affect material properties. In the nanocomposite forming steps, the base medium must flow easily into the molds. With some applications, the filler must align and not interrupt flow in specific directions where strength or conductivity is required. Fillers with high length-to-width ratios line up well in the flow of a liquid base that has yet to solidify.
Increasing the surface area of the smallest particles in nanocomposites forces them to spread out and be more evenly distributed, resulting in more consistent material properties. The aggregation of nanoparticles during the flow and curing of the base medium is caused by residual atomic charges or when the branched particles become entangled as they flow into each other. Unwanted and uneven aggregation contributes to residual stresses in the material as the base medium becomes solid. Uneven distributions of nanoparticles in critical locations could cause a design to fail, stop functioning or break down. One method that ensures uniform particle distribution is sonochemistry, where, in the presence of ultrasonic waves, bubbles are formed which collapse, dispersing the nanoparticles more evenly.
Of the numerous applications for nanocomposite materials, some of interest are electronics, optics and biomedical. Nanocomposites that combine a polymer-based medium with carbon nanotubes are used in the packaging of electronic components that require housings to dissipate static electrical charges and thermal buildup. For optical clarity, the optimally sized nanoparticles do not scatter light but allow it to pass while adding strength to the material. In photovoltaics, the smaller the particles, the greater the solar absorption, resulting in more electricity production. Nanoparticles in contact lenses, formed from a polymer base, change color depending on the amount of glucose in the patient’s tear fluid, indicating a diabetic’s need for insulin.
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