Over the last several decades, polymer membranes have shown promise for purifying various industrial gas mixtures. However, there are a number of potential applications in which highly polarizable gases (e.g., CO2, C3H6, C3H8, butenes, etc.) diminish membrane selectivities through the mechanism of plasticization. Plasticization is the swelling of polymer films in the presence of certain penetrants that results in increased permeation rates of all gases, but an unwanted, and often times, unpredictable loss in membrane efficiency. Current strategies for reducing plasticization effects often result in a reduction in membrane permeability. To address the need for plasticization-resistant membranes that retain good separation performance, researchers at UC Berkeley have developed a novel method for improving polymer membrane stability and performance upon the incorporation of metal-organic frameworks (MOFs). This method can be applied to a broad range of commercially available polymers as well as enable new polymers to be commercialized.