| Abstract
| - The pH-switchable ion transport and selectivity in nanopore membranes with fixed charges is theoreticallyanalyzed using a model based on the Nernst−Planck flux equations. The ionization state of the weakpolyelectrolyte groups attached to the pore surface appears to be a crucial factor in order to understand theconductive properties of the pore. The model allows for the calculation of the fluxes of all of the ionic speciesinvolved and the membrane potential. Comparison of the theoretical results with the experimental data byMartin el al. (Science1995, 268, 700−2; J. Phys. Chem. B2001, 105, 1925−34; and Adv. Mater. 2001, 13,1351−62) and Stroeve et al. (Langmuir 2000, 16, 2401−4; and Langmuir 2001, 17, 5271−5) for surfacemodified nanopores with fixed charges shows that the model can describe qualitatively the changes of thepermeate ion flux and the membrane potential with the pH and the solute concentration of the external solutions.The effect of applying an electric potential to the nanopore walls is also studied. Some of the main characteristicsthat allow a simple description of pH-switchable effects on nanopore membranes with fixed charges areclearly shown.
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