ABSTRACT
This chapter aims to describe the gas transport properties and other attributes of polymers that are important for candidate materials for gas separation membranes and to explore how these properties are related to the polymer molecular structure and are interrelated to one another. It focuses on polymers with relatively rigid, usually aromatic, backbones and deals with a class of high free volume polymers that generally have carbon-carbon chain backbones. The chapter reviews basic principles of membrane material characterization followed by a detailed demonstration of many of the most important principles of molecular design using the polysulfone family of polymers. It examines the effects of polymer molecular structure on intrinsic gas transport characteristics and other properties that reflect chain stiffness, mobility, and packing for a number of glassy polymers. Polymeric isomers often have substantially different properties that seem to relate to issue of symmetry. The processes of sorption and permeation can change the state of the film.
