(422c) A Modified Free Volume Model to Designing High-Performance Polymers for Gas Separation

Understanding the structure and property relationship is critical to designing high-performance membrane materials for gas separation, particularly for materials with balanced permeability and selectivity above or near the Robeson’s upper bound. Herein, the free volume model is adapted to describe the upper bounds for the separation of several gas pairs, such as O2/N2, He/CH4, CO2/CH4, and H2/CO2. The results are more or less consistent with the conventional activation energy model reported in the literature. More importantly, this model can be used to predict the structure of polymers with targeted separation properties on demand. I will demonstrate that for the separation of specific gas pairs, polymers with specific free volumes can be identified to achieve the best performance. The model can also satisfactorily predict the effect of temperatures on separation properties, which may be needed for industrial H2/CO2, CO2/CH4, H2/C3H8, and O2/N2 separations. Such an understanding may provide an effective route for the high throughput design of membrane materials through data mining or machine learning.