Inclusion complexes of single-C60-end-capped poly(ethylene oxide) with cyclodextrins

Abstract

Single-C60-end-capped poly(ethylene oxide) (FPEO) forms a stoichiometric inclusion complex with α-cyclodextrin in high yield. The complex was characterized by XRD, 13C CP/MAS NMR, 1H NMR, DSC, and TGA. The incorporation of C60 results in no apparent change in the crystal structure. No complex forms between FPEO and β-cyclodextrin. γ-Cyclodextrin (γ-CD) and FPEO form a thermoreversible gel in aqueous solution instead of a stoichiometric crystalline complex, whereas uncapped polymers form crystalline inclusion complexes with γ-CD in high yields. Interestingly, in a γ-CD/FPEO/PEO aqueous solution, two PEO chains are able to "recognize" each other and thread through the γ-CD cavity to form a γ-CD/PEO inclusion complex.