Poly(ethylene glycol) (PEG) can form either the inclusion complex with alpha-cyclodextrins (alpha-CDs) through host-guest interactions or the interpolymer complex with poly(acrylic acid) (PAA) through hydrogen-bonding interaction. Mixing alpha-CD, PEG, and PAA ternary components in an aqueous solution, the competition between host-guest and hydrogen-bonding interactions occurs. Increasing feed ratio of alpha-CD:EG:AA from 0:1:1 to 0.2:1:1 (molar ratio), various interesting supramolecular polymer systems, such as hydrogen-bonding complex, dynamic polyrotaxane, crystalline inclusion complex, and thermoresponsive hydrogel, are successively obtained. (c) 2008 Wiley Periodicals, Inc.