Nanoporosity of Polymer Membrane Materials and Sorbents According to Positron Annihilation and Low-Temperature Gas Sorption Data

Based on the experimental data obtained by the authors in a number of previous studies, the limits of applicability of positron annihilation lifetime spectroscopy (PALS) and low-temperature gas sorption (LTGS) to determination of nanoporosity (size distribution of nanopores in the range from a few fractions of a nanometer to 50 nm) in polymeric membrane materials and sorbents are discussed. It turns out that none of these methods is universal. The possibility of using each of them is determined by different factors, with the cases considered being finely divided polymer materials and the membranes per se cast from powders. It has been shown that the particle size factor is important for the applicability of LTGS. The possibility of using PALS depends on the concentration of nanopores of a given size.