Transport in Nonionic Polymers

The driving force for ion transport in a polymer phase can be either a concentration gradient (diffusive transport), an electric field (migration), or both. The resulting flux of the ionic species i, Ji, is usually described by the Nernst-Planck equation  

Again transport in the film is considered to proceed only in the x direction, i.e., across the film. The diffusion coefficient A can be correlated with the physical mobility u (in units of cm V s ) via the Einstein relation  

The specific ionic conductivity of the considered phase is given by 

The migrational transport frequently proceeds by both anions and cations. In the absence of concentration gradients, the fraction of the ionic current transported by a particular species i is the transference number r, 

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