Cover Image, Volume 58, Issue 9

Gas permeation through a glassy polymer far from the steady state is a complex process. Presented in the cover image from Frances A. Houle and colleagues for the article on page 1207, the membrane (cyan) is exposed to a gas (purple). Binding sites (gray) are slowly created within the polymer and filled when they become available. Eventually, steady‐state permeation with a constant gas concentration within the membrane is reached. Consideration of this polymer response is essential in capturing pre‐steady state gas permeation behavior. (DOI: 10.1002/pol.20200053 )