A New Charge-Mosaic Membrane from a Multiblock Copolymer

A charge-mosaic membrane was prepared from a pentablock copolymer of the BABCB type by selectively introducing anion and cation exchange groups into the microseparated phases. The three-layer lamellar structure of the starting pentablock copolymer film was not disturbed by the modifications. The membrane obtained was highly permeable only to sodium chloride in mixed aqueous solutions of sodium chloride and organic species of low molecular weight, such as sucrose. Marked pH-dependent permeabilities were also observed for amino acids.