This work reports the formation and detailed characterization of the ycyclodextrin (gamma-CD) inclusion compounds (ICs) formed with two poly (vinyl chloride) samples with different isotactic content. The lCs were characterized by X-ray diffraction, solid state C-13-NMR, solution H-1-NMR, FT-infrared, differential scanning calorimetry, and thermogravimetric analysis. Experimental evidence of the inclusion of the guest polymer chains into the narrow channels created by the gamma-CD crystalline host lattice has been obtained. Examination of coalesced poly (vinyl chlorides) (PvCs) obtained after the host gamma-CD is removed reveals different characteristics specifically for the coalesced PVC sample with higher isotactic content. Am increase in Tg was observed by DSC for this PVC. To the contrary, the T-g of the coalesced PVC sample with lower isotactic content is almost the same as that of the as-synthesized sample. Thermogravimetric analysis indicated that coalesced PVC with higher isotactic content acquires a degree of stabilization after modification by threading into and being extracted from its gamma-CD IC. The results suggest that an irreversible conformational change takes place when PVC forms ICs with a solid host lattice like T-CD. The PVC molecules extend and reorganize into a more stable conformation in the IC, consequently improving the properties of the coalesced sample. (C) 2007 Wiley Periodicals, Inc.