Gas transport in poly[bis(trifluoroethoxy)phosphazene]

The gas transport parameters of 14 gases in poly[bis(trifluoroethoxy)phosphazene] were determined at temperatures ranging from about 12 to 45°C by the time‐lag method. The phosphazene polymer demonstrated a high diffusivity; rather high crystallinity was expected, though. The permeation data determined were between polydimethylsiloxane and low‐density polyethylene. The most interesting characteristic shown over the course of experimentation is that poly[bis(trifluoroethoxy)phosphazene] has significantly high solubility for CO 2 , as compared to other gases. The polar side groups—i.e., the electron‐withdrawing trifluoroethoxy parts—which should contribute specific interaction with CO 2 , were shown to be stronger than their interaction with the polar N 2 O molecule. The sorption behavior is compared with those of other rubbery polymers, while phosphazene polymer characteristics are also discussed.