Nano-Filler Forms

All three types have some current interest as fillers. The platy ones (mainly in the form of layered silicates) are receiving by far the most attention, and will be focussed on in this work. The various forms are briefly discussed next. 

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It is proposed that thermal aging of the Cloisite/PDMS elastomers promotes the reformation of the siloxane network into a more thermodynamically stable form though a series of catalytically driven chain backbiting, hydrolysis and recombination reactions. This produces a siloxane network with increased thermal stability which is more intimately associated with the nano-filler. 

Other nano-fillers have also investigated. Cao et al. [253] reported the utilization of multiwalled carbon nanotubes (MWCNTs) as filler-reinforcement to improve the performance of plasticized starch (PS). The PS/MWCNTs nanocomposites were prepared by a simple method of solution casting and evaporation. The results indicated that the MWCNTs dispersed homogeneously in the PS matrix and formed strong hydrogen bonding with PS molecules. Besides the improvement of mechanical properties, the incorporation of MWCNTs into the PS matrix also led to a decrease in the water sensitivity of the PS-based materials. 

Amphiphilic block copolymers forming e.g. micelles and aggregates, and stabilizing additives and (nano)fillers... 

While neither the MWNT elongated cylinders nor the exfoliated clay sheets resulted in self-extinguishing behavior, they did slow the rate of fire spread by reducing the rate of heat evolution. Both of these nano materials form a kind of synthetic char, more effectively than larger particulate fillers, and act as heat shields. It may be that combinations of several types of materials will prove most effective in reducing fire spread. 

The current drive to discover and develop new materials constantly leads to the discovery and/or synthesis of more and better performing [nano] fillers with potential applications that push the limits of what is possible. In spite of their very attractive and exciting properties, CNTs are not the only fillers that can be incorporated into a polymer matrix by latex technology. In fact, any filler that can be obtained in the form of a colloidally stable aqueous dispersion can, in principle, be used. 

The barrier properties of biodegradable melt-mixed polyesteramide/octa-decylamine treated montmorillonite clay have been studied by Krook et Density measurements indicated that shear-induced voids were formed in the nanocomposite, and these were, according to transmission electron microscopy, almost exclusively located between the clay sheets. The presence of voids limited the improvement in barrier properties with increasing filler content. The voids were the major reason for the low efficiency of the nano-fillers in blocking diffusion of the penetrant molecules. 

The uniform nano-filler distribution, combined with the presence of the continuous silicate phase, formed during the preparation of hybrids, represents the key to advance structural materials with simultaneous improvement of several important physical properties, such as mechanical, thermal and barrier properties. 

Up to now, most efforts have been directed towards the preparation of uniformly sized spherical MIP particles in the micrometre range. This is the obvious consequence of the need for this kind of materials as fillers for high-performance chromatographic columns, capillaries for electrophoresis, cartridges for solid-phase extractions and other applications requiring selective stationary phases. Additionally though, strategies for the preparation of other more sophisticated MIP forms, such as membranes, (nano)monoliths, films, micro- and nanostructured surfaces etc. 

This is stimulated by selective interaction of described inorganic fillers with aggressive media. Hydrate complexes formed fill macropores and microcracks of coatings. This process results in repair of defects and the material is hardened and becomes less penetrable [6,7], The free volume of nano-heterogenic coatings simultaneously decreases. 

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