Electronic polymers charge mobility

There may be contributions to the conductivity from several different types of carrier, notably electrons and holes (a hole is an electron vacancy carrying an equivalent positive charge) in electronic conductors, and cation and anion pairs in ionic conductors. Theories of conduction aim to explain how n and fj. are determined by molecular structure and how they depend on such factors as temperature and applied field. In addition, in polymers the mobility will be affected by the sample morphology. Just as a large range of conductivity is observed for different materials so there is a large range of mobility values. Data for a selection of systems are displayed on the mobility chart (Fig. 4.2). 

Polyaniline filaments within the mesoporous channel host (aluminosilicate) have significant conductivity, and this demonstration of conjugated polymer with mobile charge carriers in nanometer channels represents a step toward the design of nanometer electronic devices. These composites have potential as stable molecular wires, which can be applied in the design of batteries and systems to accumulate electric charge. SBA-15 with polyaniline inside the pore channels was used as a dispersed phase in electro-rheological (ER) fluids. 

Implications. These results have an important implication concerning the use of Fourier analysis of DC transients in polymeric materials to extract the frequency-dependence of the dielectric response (12)- In order for the principle of superposition to apply the electric field inside the material being measured must be time- and space-invariant. This critical condition may not be met in polymers which contain mobile ionic impurities or injected electrons. Experimentally, we can fix only the average of the electric field. Moreover, our calculations demonstrate that the bulk field is not constant in either time or space. Thus, the technique of extracting the dielectric response from the Fourier components of the transient response is fundamentally flawed because the contribution due to the formation of ionic and electronic space-charge to the apparent frequency-dependent dielectric response can not generally be separated from the dipole contribution. 

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