Study of Microporosity of Polymer Glasses Using Techniques of Positron Annihilation and Low-Temperature Sorption of Carbon Dioxide

Abstract

The nature of micropore size distribution in a number of amorphous polymer glasses (membrane materials and sorbents) has been discussed on the basis of data on positron annihilation lifetime spectroscopy (PALS) and low-temperature CO₂ gas sorption (LTGS). The LTGS (CO₂) technique in combination with mathematical processing by the density functional theory gives a multimodal size distribution of micropores in the range of effective diameters of 0.5–1.5 nm for PIM-1 type polymers of intrinsic microporosity. The positron annihilation data (time distribution of annihilation emission events) are also satisfactorily processed under the assumption of multimodality. The results have been discussed in terms of the “local rigidity” of the materials under consideration.