Transport field-driven

Electric-field-driven transport in media made of hydrophilic polymers with nanometer-size pores is of much current interest for applications in separation processes. Recent advances in the synthesis of novel media, in experimental methods to study electrophoresis, and in theoretical methodology to study electrophoretic transport lead to the possibility for improvement of our understanding of the fundamentals of macromolecular transport in gels and gel-like media and to the development of new materials and applications for electric-field-driven macromolecular transport. Specific conclusions concerning electrodiffusive transport in polymer hydrogels include the following. 

Figure 11-18. a) Morphological instability of the AgCI/KCl phase boundary in the electric field-driven transport couple, b) Morphological instability of the concentration profile of the AgCl-NaCI interdiffusion couple under the action of an electric field (see text) [S. Schimschal (1993)]. 

Fig. 13. Possible sign combinations involving the sign of the surface charge at the metal—oxide interface and the sign of the charge of the field-driven mobile species originating at the metal—oxide interface, together with schematic diagrams of the concentration profiles for the mobile species, (a) Field-driven cation interstitial (or anion vacancy) transport (b) Field-driven electron transport.

A. Tikhonov, R.D. Coalson, Yu. Dahnovsky, Calculating electron transport in a tight binding model of a field-driven molecular wire Floquet theory approach, J. Chem. Phys. 116... 

Pai et al. (1983) measured hole mobilities of a series of bis(diethylamino)-substituted triphenylmethane derivatives doped into a PC and poly(styrene) (PS). The mobilities varied by four orders of magnitude, while the field dependencies varied from linear to quadratic. In all materials, the field dependencies decreased with increasing temperature. The temperature dependencies were described by an Arrhenius relationship with activation energies that decrease with increasing field. Pai et al. described the transport process as a field-driven chain of oxidation-reduction reactions in which the rate of electron transfer is controlled by the molecular substituents of the hopping sites. 

Fig. 41. The simple semicircular IMPS response is predicted by Eq. 93 for the case where photogenerated carriers diffuse or migrate through a nanocrystalline network without being trapped. The second IMPS plot is predicted by a more exact treatment of field driven electron transport [78]. Note that in this case, the plot crosses the imaginary axis at high frequencies and spirals into the origin.

Oekermann, T., Yoshida, T., Boeckler, C, Caro, J., and Minoura, H. (2005) Capacitance and field-driven electron transport in electrochemically self-assembled nanoporous ZnO/dye hybrid films. J. Phys. Chem. B, 109, 12560-12566. 

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