Section 4 - Transport and permeation (diffusion of materials)

Abstract

Experimental and theoretical basis studies have attempted to understand the diffusion of molecules (solvents, polymeric materials etc.) in gels. Advances in instrumentation for diffusion coefficient determination have contributed significantly to this field. These techniques include the dynamic light scattering technique, nuclear magnetic resonance spectroscopy (NMR), and the forced Raleigh scattering technique. Application studies have been using the results of these basic studies. The chapter discusses examples of recent studies after briefly describing the fundamental theories and measurement methods related to gels diffusion. In particular, those examples in which the NMR technique has been used are discussed in detail in the chapter. The classic method for measuring the diffusion coefficient within a gel is to measure the amount of the exclusion of the solute or the amount of permeation through the gel.