The article discusses the issue of penetrant-induced plasticization in microporous polymer membranes, which has hindered the industrial deployment of many polymers for gas separation. The authors provide an integrative discussion on plasticization theory and gas transport models, comparing these theories with a comprehensive database of plasticization characteristics of microporous polymers. They analyze the correlations between specific polymer properties and plasticization behavior, including plasticization pressures from pure-gas and mixed-gas permeation tests. The article also evaluates common strategies to mitigate plasticization and suggests future research directions. The introduction highlights the environmental impact of distillation and the need for alternative separation technologies, such as membrane-based gas separations. The review covers gas transport theory, polymer chain mobility, and methods to measure these parameters, as well as plasticization mitigation strategies. The authors emphasize the importance of understanding plasticization to advance the field of microporous polymer membranes for energy-efficient gas separations.The article discusses the issue of penetrant-induced plasticization in microporous polymer membranes, which has hindered the industrial deployment of many polymers for gas separation. The authors provide an integrative discussion on plasticization theory and gas transport models, comparing these theories with a comprehensive database of plasticization characteristics of microporous polymers. They analyze the correlations between specific polymer properties and plasticization behavior, including plasticization pressures from pure-gas and mixed-gas permeation tests. The article also evaluates common strategies to mitigate plasticization and suggests future research directions. The introduction highlights the environmental impact of distillation and the need for alternative separation technologies, such as membrane-based gas separations. The review covers gas transport theory, polymer chain mobility, and methods to measure these parameters, as well as plasticization mitigation strategies. The authors emphasize the importance of understanding plasticization to advance the field of microporous polymer membranes for energy-efficient gas separations.