Patent ID: 8481017

Claim:
A medium for isolating or releasing an electrostatically charged component from or into an aqueous composition, the medium comprising a polyelectrolyte film on at least one surface of an article: the polyelectrolyte film comprises an interpenetrating network of a predominantly positively charged polymer and a predominantly negatively charged polymer; the predominantly positively charged polymer, the predominantly negatively charged polymer or both contain (i) a copolymer comprising a pH sensitive imidazole repeat unit having a pKa between 3 and 9 and a charged pH insensitive repeat unit, or (ii) a redox sensitive repeat unit selected from the group consisting of quaternized bipyridine repeat units, coordinated metal repeat units, pyrrole repeat units, aniline repeat units, thiophene repeat units and combinations thereof having a redox potential between +1.2 volts and −1.2 volts versus a standard hydrogen electrode; and the article is (iii) a porous substrate when the predominantly positively charged polymer, the predominantly negatively charged polymer or both contain the pH sensitive imidazole repeat unit or (iv) an electrically conductive substrate when the predominantly positively charged polymer, the predominantly negatively charged polymer or both contain the redox sensitive repeat unit.