The present invention provides a surface modified polymeric gas separation membrane having improved selectivity, particularly for oxygen/nitrogen gas mixtures, prepared by forming a membrane of a polymer having the structural formula ##STR1## wherein R and R" can be the same or different linear, branched...http://www.google.com.au/patents/US5073175?utm_source=gb-gplus-sharePatent US5073175 - Fluorooxidized polymeric membranes for gas separation and process for preparing them
