1.8 Thermally Rearranged Polymeric Membranes: Materials and Applications

Thermally rearranged (TR) polymers are microporous with high fractional free volume and narrow cavity size distribution. As a result, they exhibit excellent gas permeability and selectivity, exceeding the Robeson upper bound. This article provides a detailed discussion on the influence of TR polymer types on free volume topology. General principles are offered for TR polymer design, including the choice of monomers and synthesis routes, and their relationships with the polymer free volume topology and eventually the gas permeation properties. Other aspects including characterization techniques and industrial-scale implementation and applications are also provided.