Photoresponsive Polymer and Polymer Composite Membranes for Gas Separation

Stimuli-responsive materials, referred to as “smart” or “intelligent” materials, have gained significant attention in the separation fields, including gas separation. Among a variety of available stimuli, the use of light as a nondestructive, cost-efficient, chemical-reagent-free stimulus with a relatively fast response is very promising. Herein, we summarize and highlight the approaches applied for the synthesis of photoresponsive organic polymeric membranes, inorganic metal–organic framework thin films, and inorganic–organic mixed-matrix membranes. We discuss the application of these materials for gas separation and provide selected state-of-the-art examples from recently conducted studies. Additionally, the photoresponsive gas separation membrane testing cell plays a crucial role in evaluating and comparing the performance of photoresponsive membranes in the gas separation process. Therefore, we review the development of photoresponsive gas separation membrane testing cells along with the ascribed drawbacks and limitations. A third generation testing system designed to highlight test accuracy is proposed and discussed.