Effect of Porosity on Ion Transport Through Polymers and Polymer-Based Composites Containing Inorganic Nanoparticles (Review)

This chapter is devoted to organic-inorganic composite ion exchange resins and membranes. We ascertain interrelation between composition, morphology, and porous structure of the materials on the one hand and ion transport through them on the other hand. The composites for different practical application (fuel cells, ion exchange columns, electrodialysis) are in a focus of attention. Porosity of the polymer constituent was determined with a method of standard contact porosimetry, which gives information about pores in a very wide diapason (from 2 nm to 200 μm). In this context, pore formation in ion exchange polymers during swelling is considered. A number of parameters, which are obtained from porosimetric measurements, can be used for interpretation of ion transport regularities, particularly evolution of electrical conductivity. Embedded non-aggregated nanoparticles, their aggregates, and agglomerates differently affect porosity of the polymer constituent: they are able to block, stretch, and squeeze pores. As a result, the composites demonstrate different rate of ion transport depending on amount and size of inorganic particles, which can be formed purposefully. The approach to the formation of one or other types of particles has been considered.