Metal-polymer film materials sensor properties

In addition to the modified electrodes described in the previous sections, which usually involve a conductive substrate and a single film of modifying material, more complicated structures have been described. Typical examples (Figure 14.2.4) include multiple films of different polymers (e.g., bilayer structures), metal films formed on the polymer layer (sandwich structures), multiple conductive substrates under the polymer film (electrode arrays), intermixed films of ionic and electronic conductor (biconductive layers), and polymer layers with porous metal or minigrid supports (solid polymer electrolyte or ion-gate structures) (6,7). These often show different electrochemical properties than the simpler modified electrodes and may be useful in applications such as switches, amplifiers, and sensors. 

Polymer/sihca composite blends, not only improve the physical properties, snch as the mechanical properties and thermal properties of the materials, but they can also exhibit some unique properties that have attracted strong interest in many industries. Besides common plastics and rubber reinforcanent, many other potential and practical applications of this type of nanocomposites have been reported coatings, flame-retardant materials, optical devices, electronics and optical packaging materials, photo resist materials, photo-luminescent conducting film, per-vaporation membrane, ultra-permeable reverse-selective membranes, proton exchange membranes, grouting materials, sensors and materials for metal uptake, etc. As for the colloidal polymer/sihca nanocomposites with various morphologies, they usually exhibit enhanced, even novel, properties when compared with the traditional nanocomposites and have many potential applications in various areas. 

It was found that transition to nanocomposites could also improve mechanical properties and promote stabilization of the basic material s parameters (Konig 1987). For example, it was established that in CNTs-polymer composites, the presence of carbon nanotubes inside the polymeric matrix can provide a mechanical support to the polymeric chain s conformational rearrangement. CNTs are hollow nanopipes, and therefore the incorporation of CNTs in a metal oxide matrix can provide better gas permeability for sensing materials and thus enhance gas diffusion into the bulk film. Thus, combination of CNTs with metal oxide (see Fig. 12.1) can lead to development of gas sensors with improved rate of response. 

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