Polystyrene-block-polyvinylpyridine (PS-b-P4VP) polypseudorotaxanes with cucurbiturils (CB) were prepd. from water sol. PS-b-P4VPH+ polymer and CB in aq. soln. at room temp. At acidic and neutral pH, the pyridinium block of PS-b-P4VP is protonated (PS-b-P4VPH+) pushing CB to preferably host the P4VP block. At basic pH (pH 8), P4VP is not charged and thus is not able to strongly complex CB. This phenomenon was verified further by monitoring the release of pyrene, a hydrophobic cargo model, from a PS-b-P4VPH+/CB micellar membrane. Release study of UV active pyrene from the membrane at different pH values revealed that the system is only operational under basic conditions and that the host-guest interaction of CB with P4VPH+ significantly slows down cargo release.