Models of Diffusion in Porous Polymer Matrices

Macroscopic Models of Diffusion in Porous Polymer Matrices 

Consider a protein-loaded matrix constructed as a thin slab. Release of the protein occurs essentially through the top and bottom faces of this slab because the thickness of the slab is small compared to the other dimensions. The desorption of protein from this slab can be described by Pick s second law of diffusion  

Since protein is initially distributed uniformly throughout the slab, and since we assume that protein is rapidly removed from the surface of the matrix, the following initial and boundary conditions apply for this geometry  

The cumulative fraction of protein released (i.e., the amount released at time t divided by the amount originally dispersed in the matrix) is found by 

For cumulative fractions released of 0.6, an approximate solution can be used  

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