Novel side chain polypseudorotaxanes with cucurbit[7]uril (CB[7]) threaded onto the side chains are synthesized from a water-soluble polymer and CB[7] in water by simple stirring at room temperature. CB[7] beads could move from the hexyl groups to the benzyl and a part of viologen units in the side chains of polymer when the molar ratio of CB[7] to the monomer reaches from 1 to 2 as shown by H-1 NMR studies, and it is considered that the hydrophobic and charge-dipole interactions of CB[7] are the driving forces. The sizes of the polypseudorotaxanes with different molar ratio of CB[7] to 4VBVHeP in aqueous solution increase with increasing the molar ratio of CB[7] to 4VBVHeP as found by DLS and resonance light scattering, while the typical cyclic voltammograms and UV-vis data indicate that CB[7] are not threaded in the viologen units of P4VBVHeP, and the oxidation reduction characteristic of the polymer is remarkably affected by the addition of CB[7]. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 2138-2146, 2011