Polymer-inorganic nanocomposites

To put the current research in LDH/polymer nanocomposites into context, we will first give a brief review of 2D-hybrid materials composed of a guest polymer and an inorganic host structure. 

Organic molecules such as aniline, pyrrole and 2,2 -bithiophene have been intercalated and polymerized within the galleries of clay minerals, FeOCl, V2O5 gel and other layered hosts to yield multilayered inorganic/organic polymer nanocomposites... 

Provided in this chapter is an overview on the fundamentals of polymer nanocomposites, including structure, properties, and surface treatment of the nanoadditives, design of the modifiers, modification of the nanoadditives and structure of modified nanoadditives, synthesis and struc-ture/morphology of the polymer nanocomposites, and the effect of nanoadditives on thermal and fire performance of the matrix polymers and mechanism. Trends for the study of polymer nanocomposites are also provided. This covers all kinds of inorganic nanoadditives, but the primary focus is on clays (particularly on the silicate clays and the layered double hydroxides) and carbon nanotubes. The reader who needs to have more detailed information and/or a better picture about nanoadditives and their influence on the matrix polymers, particularly on the thermal and fire performance, may peruse some key reviews, books, and papers in this area, which are listed at the end of the chapter. 

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. 

Keywords Microemulsion polymerization Microemulsion reaction Water-in-Oil (W/O) microemulsion Oil-in-Water (0/W) microemulsion Bicontinuous microemulsion Functional membranes and inorganic/polymer nanocomposites... 

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. 

This bicontinuous-microemulsion polymerization method can also be used to synthesize polymer nanocomposites containing Si02 [101], Ti02, ZnO and many other semiconductors. The advantage of this method is that the nanoparticles of inorganic materials can be dispersed in the polymer matrix fairly uniformly. The only requirement is that nanomaterials should be first stabihzed... 

MEM devices, thin films, (fullerenes, nanotubes, nanofibers, integrated circuits) dendritic polymers, nanoparticles, inorganic-organic nanocomposites nanoelectronic devices)... 

It is well known that small molecules can be removed from larger molecules using inorganic materials such as molecular sieves. However, this approach contaminates the polymer with inorganic particulates. The only literature teaching this approach are Russian patents claiming the addition of silica gel [27] and mont-morillonite clay [28] to absorb styrene from PS. The advances in nanocomposite technology in recent years may allow further development of this approach. 

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. 

Y. Wei, Nanocomposite/Hybrid Materials of Electroactive Polymers with Inorganic Oxides for Biosensor Applications, Storming Media, Washington DC, 2001. 

The most commonly studied polymer nanocomposites are clay-based nanocomposites, mainly with montmorillonite (MMt) as layered silicate filler (Scheme 15.12). Upon incorporation of organomodihed clays (organoclays) into a polymer matrix, two nanomorphologies (Scheme 15.13) can be obtained, either intercalation of the polymer chain in between the clay platelets keeping the stacking of the sheets, or exfoliation of the clay platelets with a disordered dispersion of the inorganic sheets in the polymer. 

Thin-film metal (metal oxide)/polymer nanocomposites with different inorganic phase contents were obtained by using the cold-wall vacuum co-deposition technique. A range of metals was shown to be applicable to form nanocomposite thin films with PPX, i.e., Al, Ti, Pd, and Sn. AFM studies show the metal nanoparticles to have a size of 7-50 nm. Within the composite the polymer forms more or less spherical globules with a maximum size of about 200 nm. The interfacial regions between neighbouring polymeric spherulites contain nanoparticles of the inorganic filler. 

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