(660d) Fundamental Water and Salt Transport Properties of a Novel Sulfonated Styrenic Pentablock Copolymer

Sulfonated polymers have been shown to exhibit favorable tolerance to the chlorine compounds that are commonly used to disinfect water. As such, these materials are being studied and optimized for use as chlorine-resistant desalination membrane materials. Fundamental transport studies are needed to understand the structure-property relationships that exist in these materials. These studies will allow further optimization of sulfonated polymers for desalination applications. Here, water and salt transport data have been measured for a series of sulfonated styrenic pentablock copolymers where the degree of sulfonation and the copolymer structure have been varied. The results are presented within the framework of the solution-diffusion model for transport through non-porous materials. In addition, positron annihilation lifetime spectroscopy (PALS) has been used to measure the free-volume characteristics of these materials. Since free-volume is directly related to transport properties in these materials, the PALS technique provides valuable information that can be used to correlate transport properties. Water and salt transport properties will be discussed within the framework of fundamental tradeoff relationships that have been observed in desalination materials. Furthermore, water and salt transport properties will be compared to salt rejection data using traditional reverse osmosis theory.