Pore volume fraction accessible, polymer fractionation

Here Cp is the accessible pore volume fraction of the gel which is a fijnction of the pore size distribution as well as the size of a polymer molecule. The value of p is given by Equation 3 ... 

These concerns can be addressed partially through the use of mixed-matrix membranes [77-79]. Dispersing the microporous material in the form of small particles within a polymeric matrix simplifies membrane formation dramatically. Mixed matrix materials possess transport properties intermediate between those of the polymer matrix and the microporous particle and operating temperatures are limited by the thermal stability of the polymer matrix. However, proper selection of the matrix, control of particle volume fraction, and development of a membrane formation process can yield materials with properties that approach those of the particles [77-78]. Special attention must be given to the particle-polymer interface. If the interface morphology is uncontrolled, the matrix may 1) not wet the particle leaving a non-selective void around the particle, 2) enter the particle and block pores, or 3) rigidify around the particle and block access to it [79]. 

Large molecules of polymers are partially or fully excluded from the packing pores and therefore they elute faster than the eluent molecules. Naturally, the macromolecules outrun also their original solvent. The acceleration of polymer relative to eluent molecules rises with increasing size of macromolecules because the volume fraction of accessible pores decreases correspondingly. As a result, both the distribution constant K and the retention volume of polymer... 

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