Preparation and characterization of inclusion complexes of poly(alkyl vinyl ether) with cyclodextrins

gamma-Cyclodextrin (gamma-CD) has been found to form inclusion complexes with poly(methyl vinyl ether) (PMVE), poly(ethyl vinyl ether) (PEVE), and poly(n-propyl vinyl ether) (PnPVE) of various molecular weights to give stoichiometric compounds in crystalline states. alpha-Cyclodextrin (alpha-CD) and beta-cyclodextrin (beta-CD) did not form complexes with poly(alkyl vinyl ether)s of any molecular weight, gamma-CD did not form complexes with the low molecular weight analogs, such as diethyl ether and trimethylene glycol dimethyl ether. The yields of the complexes of gamma-CD with PMVE increased with increasing molecular weight (MW) of PMVE and reached saturation at about MW 2000. The yields of the complexes of gamma-CD with PEVE and PnPVE increased with increase in MW, reached a maximum at a MW of about 1000 for PEVE and about 250 for PnPVE, and decreased with a further increase in the MW. Complexes were isolated and found to have a 3 : 1 (monomer unit:CD) ratio. The complexes were characterized by IR, H-1 NMR, C-13 NMR, and X-ray (powder), thermal and elemental analyses. The structures of the complexes are discussed.