(695b) Intrinsically Microporous Polyimides Incorporating TröGer's Base (TB) for Membrane Gas Separation

Trögerâ??s Base (TB), which is a rigid, V-shaped, and bridged bicyclic amine, has been studied during more 130 years especially in organocatalysis and stereochemistry and recently, McKeown introduced the TB units into polymers of intrinsic microporosity (PIMs) for gas separation membranes. The resultant PIM-TBs exhibited an improvement in gas transport behaviors, indicating that incorporation of the TB units into polymer backbones endows polymer rigidity and microporosity.

In this study, rigid TB moieties were incorporated in polyimides (PI-TBs) in-situ polycondensation reactions using dimethoxymethane (DMM). Polyimides are commonly used for membrane gas separation due to their advantages such as good thermal and chemical stabilities, and processability. Solution-processable PI-TB membranes in this work exhibited an enhancement of mechanical properties and gas transport behaviors compared to conventional polyimide membranes, indicating that TB units imparted their microporosity and improved free volume elements of polyimide chains.

Six copolyimides incorporating Trögerâ??s Base (CoPI-TBs) were also investigated for the first time. The CoPI-TBs were prepared in-situ TB formation with dimethoxymethane (DMM) and two kinds of diamines, imide-containing diamines and three kinds of flourene-based diamines. Molecular architecturing of CoPI-TBs was tailored of the ratio of two diamines and species of flourene moieties and the structure-property relationship including the physical properties and gas separation properties of the corresponding CoPI-TBs was evaluated.