Pervaporation performance of trifluoroethoxy substituting polyphosphazene membrane for different organic compounds aqueous solutions

A series of phosphazene heteropolymers (NP (OC6H4C3H55) x (OC6H5) y (OCH2CF3) z ) n ) with different percentages of 2,2,2-trifluoroethoxy groups were synthesized and found to have a high affinity for VOCs through pervaporation experiments and sorption studies. The pervaporation performance of as-prepared membranes for removal of tetrahydrofuran, acetone and ethanol from water was characterized, in order to study the effect of 2,2,2-trifluoroethoxy pendant group on pervaporation performance. The membranes had better selectivity for THF/water and acetone/water (maximum 30.2 and 24.1, respectively) compared with a polydimethylsiloxane membrane. As the content of 2,2,2-trifluoroethoxy group increased, both selectivity and flux was increased for ethanol/water. However, selectivity for THF/water and acetone/water was decreased. The swelling and sorption experiments of polymers, solubility parameter and diffusivity analysis provide insight into the process.