Both star-shaped poly(P-caprolactone) (PCL) having 4 arms (4sPCL) and 6 arms (6sPCL) and linear PCL having 1 arm (LPCL) and 2 arms (2LPCL) were synthesized and then investigated for inclusion complexation with alpha-cyclodextrin (alpha-CD). The supramolecular inclusion complexes (ICs) were in detail characterized by H-1 NMR, differential scanning calorimetry, thermogravimetric analysis, wide angle X-ray diffraction, solid-state carbon nuclear magnetic resonance spectroscopy using cross-polarization and magic-angle spinning, and Fourier transform infrared, respectively. The stoichiometry (CL:CD, mol:mol) of all ICs increased with the increasing branch arm of PCL polymers, and it was in the order of alpha-CD-6sPCL1 ICs > alpha-CD-4sPCL ICs > alpha-CD-2LPCL ICs > alpha-CD-LPCL ICs. All analyses indicated that the branch arms of star-shaped PCL polymers were included into the hydrophobic alpha-CD cavities and their original crystalline properties were completely suppressed. Moreover, the ICs of star-shaped PCL with alpha-CD had a channel-type crystalline structure similar to that formed between the linear PCL and alpha-CD. Furthermore, the thermal stability of the free PCL polymers probably controlled that of the guest polymers included in the ICs. (c) 2005 Wiley Periodicals, Inc.