High Free Volume Polyimide and Its Use in Gas Separation

Abstract

Polymer membranes have served as a key element in many useful scientific and technological applications such as sensors, fuel cells, water purification and desalination and gas separation. However, conventional polymer membranes for gas separation are confronted with some drawbacks ? poor chemical and thermal stability with relatively low mass transport rates and low separation efficiency. It is necessary for polymer membranes to achieve both high permeability and selectivity as well as to impart strong environmental adaptability. Here we show new polyimide membranes having high internal free volume which was achieved by incorporating an iptycene-based diamine into polyimide structure. An unusual combination of properties of an iptycene makes it useful in polymer design with high internal free volume. As such, an iptycene-based polyimide membranes show relatively higher gas permeability and selectivity as compared to other polyimide membranes.