Abstract
There are numerous reasons why the exploration of dynamic free volume is particularly important for membrane materials; a few of these include the ability to gain knowledge on plasticization and competitive sorption effects on transport properties. Positron annihilation lifetime spectroscopy (PALS) is a versatile characterisation technique able to measure angstrom to meso sized pores in a variety of materials including polymeric, hybrid, and inorganic membrane materials. Within this work we present the PALS technique and its ability to determine the pore sizes and free volume distribution of a variety of membrane materials. We demonstrate how PALS can be used to observe structural changes in different environments so that we can get a better understanding of how materials behave in dynamic environments. This capability enables understanding of the material behaviour for the particular application environment being investigated and allows us to better tailor the material chemistry and processing to optimize performance.