In the broadest sense this definition can include porous media, colloids, gels and copolymers, but is more usually taken to mean the solid combination of a bulk matrix and nano-dimensional phase(s) differing in properties due to dissimilarities in structure and chemistry.
The mechanical, electrical, thermal, optical, electrochemical, catalytic properties of the nanocomposite will differ markedly from that of the component materials.
Size limits for these effects have been proposed:[1] Nanocomposites are found in nature, for example in the structure of the abalone shell and bone.
Jose-Yacaman et al.[2] investigated the origin of the depth of colour and the resistance to acids and bio-corrosion of Maya blue paint, attributing it to a nanoparticle mechanism.
From the mid-1950s nanoscale organo-clays have been used to control flow of polymer solutions (e.g. as paint viscosifiers) or the constitution of gels (e.g. as a thickening substance in cosmetics, keeping the preparations in homogeneous form).
[5] The area of the interface between the matrix and reinforcement phase(s) is typically an order of magnitude greater than for conventional composite materials.
The percentage by weight (called mass fraction) of the nanoparticulates introduced can remain very low (on the order of 0.5% to 5%) due to the low filler percolation threshold, especially for the most commonly used non-spherical, high aspect ratio fillers (e.g. nanometer-thin platelets, such as clays, or nanometer-diameter cylinders, such as carbon nanotubes).
[9] The binary phase diagram of the mixture should be considered in designing ceramic-metal nanocomposites and measures have to be taken to avoid a chemical reaction between both components.
A good example of such a combination is represented by the ceramic-metal composite of TiO2 and Cu, the mixtures of which were found immiscible over large areas in the Gibbs’ triangle of ' Cu-O-Ti.
[10] The concept of ceramic-matrix nanocomposites was also applied to thin films that are solid layers of a few nm to some tens of μm thickness deposited upon an underlying substrate and that play an important role in the functionalization of technical surfaces.
The addition of these nanoparticles in the polymer matrix at low concentrations (~0.2 weight %) cause significant improvements in the compressive and flexural mechanical properties of polymeric nanocomposites.
In addition to mechanical properties, polymer nanocomposites based on carbon nanotubes or graphene have been used to enhance a wide range of properties, giving rise to functional materials for a wide range of high added value applications in fields such as energy conversion and storage, sensing and biomedical tissue engineering.
[27] The in situ-generated nanoparticles tend to nucleate and grow on the active sites of the macromolecular chains, showing strong adhesion on the polymeric host.
Nanoscale dispersion of filler or controlled nanostructures in the composite can introduce new physical properties and novel behaviors that are absent in the unfilled matrices.
[37] In this case, magnetic nano composites have great potential for improving the efficiency of power electronic devices by providing relatively high permeability and low losses.
For example, As Iron oxide nano particles embedded in Ni matrix enables us to mitigate those losses at high frequency.