Thermo- and pH-sensitive gel membranes based on poly-(acryloyl-L-proline methyl ester)-graft-poly(acrylic acid) for selective permeation of metal ions

Thermo- and pH-responsive gel membranes were synthesized by γ-ray grafting of pH-responsive poly(acrylic acid) (AAc) onto thermo-responsive polymer gel of acryloyl-L-proline methyl ester (A-ProOMe). The gel membranes of poly(A-ProOMe) with 15 mol% graft chains of AAc exhibited both thermo- and pH-responses. Under the condition (pH 6.0, 30°C) in which the thermo-sensitive unit shrinks and the pH-sensitive unit swells, the selective permeation of Li ion over Co and Ni ions can be achieved.