Mixed matrix materials comprised of molecular sieve domains embedded in processable polymer matrices have the potential to provide membranes with higher permselectivity and equivalent productivity compared to existing membrane materials. It has been shown that successful mixed matrix materials can be formed using relatively low glass transition (T g ) polymers that have a favorable interaction with the sieves. This article extends this earlier work to include the use of more practical rigid matrix polymers with high T g s that can ultimately be used in forming high-performance mixed matrix layers for composite membranes. Initial attempts to form mixed matrix materials based on high T g polymers with a type 4A zeolite resulted in poor adhesion between the polymer and sieve. Correcting this problem was pursued in this study by forming the composite material close to the T g of the polymer by addition of a plasticizer to match the matrix T g with the solvent volatility. Forming the films at elevated temperatures presented substantial challenges, and this work discusses overcoming these challenges in detail. With some modifications in the film casting procedure, successful materials were achieved. Promising oxygen/nitrogen transport results are presented for these zeolite 4A-Matrimid/plasticizer membranes, and this data compares favorably with predictions of the well-known Maxwell model for composite systems.

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Previous studies have examined polypyrrolone and polyimide membranes for gas separations. For the first time this study examines poly(pyrrolone-imide) copolymers for the O2/N2, CO2/CH4, and C3H6/C3H8 separation. Combining these two classes of polymers is designed to provide rigidity and desirable mechanical properties in addition to high-quality gas transport properties. Specifically, the copolymer 6FDA-TAB/DAM was studied while systematically varying the TAB/DAM ratio in order to quantitatively alter the structure of the polymer matrix. Most copolymers studied exhibited results near or above the "upper bound" for O 2/N2, CO2/CH4, and C3H6/C3H8 separations. Surprisingly, a maximum in C3H6/C3H8 selectivity was found as a function of the TAB/DAM ratio, and this does not follow the trend expected based on previous literature data. A similar trend has also been observed in carbon molecular sieve materials with varying material structure. This demonstrates that certain materials may show excellent size selective properties for one application (O 2/N2 for example) and exhibit undesirable separation properties for a different application (C3H6/C3H8 in this case).