Complex formation between hydrophobic polymers and methylated cyclodextrins. Oligo(ethylene) and poly(propylene)

Abstract

We report here the complex formation between methylated cyclodextrins (CDs) and hydrophobic polymers, such as oligo(ethylene) (OE) and poly(propylene) (PP), in aqueous solutions. These polymers can be dissolved in water phases on addition of 2,6-di-O-methyl-β-CD (DM-β-CD). OE was found to be solubilized in water containing DM-α-CD. The 1H-NMR experiments showed that the 1H resonances of OE change on addition of DM-β-CD or DM-α-CD in D2O at 25 °C. The 1H signals of methyl protons of PP shifted upfield and broadened on addition of DM-β-CD. These phenomena indicate that OE and PP selectively form hydrophilic complexes with methylated CDs. The complex formation of methylated CDs depends on the length (molecular weight) of the hydrophobic polymers.