Preparation and Characterization of Inclusion Complexes of Polyisobutylene with Cyclodextrins

β-Cyclodextrin (β-CD) and γ-cyclodextrin (γ-CD) formed inclusion complexes with polyisobutylene (PIB) of various molecular weights to give stoichiometric compounds in crystalline states. α-Cyclodextrin (α-CD) did not form complexes with PIB of any molecular weight. The yields of the complexes with β-CD decreased with an increase in the molecular weight of PIB. In contrast, the yields of the complexes with γ-CD increased with an increase in the molecular weight and the complexes were obtained almost quantitatively with PIB of molecular weight 1350. The chain-length selectivity is reversed between β-CD and γ-CD. The inclusion complexes were isolated and found to be 3:1 (monomer unit:CD). The complexes were characterized by IR, 1H NMR, 13C NMR, 13C CP/MAS NMR, 13C PST/MAS NMR spectra, and X-ray (powder), thermal, and elemental analyses. The structures of the complexes are discussed.