Poly[poly(oxypropylene) phosphate]s (PPOPP, M-n = 5800, 8100, 10,400), with different POP units (400, 1200, 2000), were synthesized and applied as cation-selective macro-ionophores in a multimembrane hybrid system (MHS). The solution of PPOPP in dichloroethane formed the flowing liquid membrane (FLM) circulating between two polymer cation-exchange membranes, and subsequently, between two polymer-made pervaporation (PV) membranes. It was found that the PPOPP macroionophores activate the preferential transport of Zn2+ cations from aqueous solutions containing competing Cu2+, Ca2+ Mg2+, K+, and Na+ cations. The following separation orders were observed for PPOPPs with POP-400 and POP-1200: Zn2+ > Cu2+ >> Ca2+, Mg2+, K+, Na+, and for PPOPP with POP-2000: Zn2+ > Cu2+ Ca2+ >> Mg2+, K+, Na+. Always, the particular cations are separated as: Zn2+ > Cu2+, Ca2+ > Mg2+, and K+ > Na+. The properties of PPOPPs were compared to respective transport and separation characteristics corresponding to those of respective poly(propylene glycol)s and poly(oxypropylene) bisphosphates. The results of investigation indicate that the bifunctional character of PPOPPs is caused by the presence of ionizable groups and probably pseudocyclic POP structures. By comparing the separation of cations in the simple MHS[FLM] system and the system supported by pervaporation unit [MHS[FLM-PV] it was found that continuous dehydration of an organic FLM improves the system overall performance. (C) 2004 Wiley Periodicals, Inc.