Polyaniline /inorganic composites

Acids can act as dopants for polyaniline therefore, if the nanofibers are first doped with these acids, and subsequently exposed to the metal ions, precipitates should be formed on the surface of the nanofibers, leading to inorganic-polyaniline nanofiber composites. This idea has been applied in Section 7.3.5 to improve the detection of H2S. Another possibility is to use nanofibers as nucleation seeds to collect inorganic nanoparticles from supersaturated solutions [148]. 

Several recent reports describe using clay or other inorganic fillers to form CP composites. Polyaniline-polypyrrole composite coatings containing clay or yttria stabilized zirconia were electrodeposited onto AA 2024-T3 [158], with improved corrosion resistance of the substrate. Similarly, particulate-filled polyaniline and polypyrrole films on AA 2024-T3 were prepared electrochemically using a variety of fillers, including clay, carbon black, short carbon fiber, zirconia, and silica [159]. Again, enhanced corrosion performance for these composites was observed. 

Polyaniline (PAn)/inorganic composites have been considered as new class of materials due to their improved properties compared with those of pure conducting polymers and inorganic materials [73-77]. For example, the combination of electrical conductivity of PAn and UV sensitivity of anatase Ti02 are expected to find applications in electrochromic devices, nonlinear optical system, and photochemical devises [73], From this point of view, it is in particular interest to prepare fluoroalkyl end-capped oligomers/PAn/titanium oxide nanocomposites. In fact, fluoroalkyl end-capped acrylic acid oligomer [Rp—(ACA) —Rp]/, 2-methacryloyloxyethane sulfonic acid oligomer [Rp—(MES) —Rp]/, 2-acrylamido-2-methylpropanesulfonic acid... 

Recently, new types of organic positives, formed by a mixture of dimercaptan with polyaniline, have been reported. These composite materials appear to have an energy density higher than that of most inorganic intercalation oxides and good cyclability. However, use of these materials in practical rechargeable lithium batteries has still to be confirmed. 

More recently, nanosized polyaniline/Ni(0) composites were used as heterogeneous catalysts for arylations of acrylates and styrene (2) [42]. Efficient catalysis was achieved with aryl iodides, while bromides gave only poor conversions. In contrast to the previously developed nickel-based heterogeneous catalysts, the use of inorganic bases led only to poor yields. 

The concept of using composites with polyaniline can be used to detect other gases, such as hydrogen sulfide (H2S). Hydrogen sulfide is a very weak acid with a pK, of 7 and it cannot dope polyaniline directly. About 10 times as much weak acid is required to dope poiyaniline when compared to a strong acid (20). One way to enhance the sensitivity of polyaniline to H2S is to use inorganic-organic composite materials. 

An alternative to in situ polymerization involves direct intercalation of macromolecules into layered structures. Silicates are most often used. The insertion of polymer molecules into layered host lattices is of interest from different points of view. First, this insertion process leads to the construction of organic-inorganic polylayered composites. Second, the intercalation physical chemistry by itself and the role intercalation plays in the gain of electronic conductivity are of interest. This becomes important in the construction of reversible electrodes " or when improving the physicomechanical properties of nylon-layered silicate nanocomposites, hybrid epoxide clay composites," and nanomaterials based on hectorite and polyaniline, polythiophene or polypyrrole. ... 

Polyanilines could also be polymerized in situ within the confinement of nanometer-sized pores [29], channels of zeolites [30], and layered inorganic compounds [31] to prepare composite materials. 

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