Pervaporation of ethanol aqueous solution by polyphosphazene membranes: Effect of pendant groups

A series of phosphazene heteropolymers (NP (OC6H4C3H5)x(OC6H5)y(OR)z)n were synthesized, where different pendant groups (–OC2H5, –OCH2CF3 and –OCH2CF2CF2CF2CF2H) providing hydrophobic property were used. All the polymers are amorphous materials with good film forming property. Pervaporation experiments were performed to characterize the polymer membranes. The results showed that polyorganophosphazene material with –OCH2CF3 group had the best membrane separation performance for ethanol/water mixture under the same content of hydrophobic group. Solubility parameters calculation and sorption measurement were also performed to study the structure–performance relationship.