Supramolecular aggregations through the inclusion complexation of cyclodextrins and polymers with bulky end groups

Abstract

Mono-polyhedral oligomeric sillsesquioxane-end capped poly(epsilon-caprolactone) (mPPCL) can form inclusion complexes (ICs) with alpha- and gamma-cyclodextrins (CDs) but not with beta-CD. These CD ICs have been characterized with X-ray diffraction, solid-state C-13 cross-polarization/magic-angle-spinning NMR spectroscopy, H-1 NMR spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and scanning electron microscopy. The poly(epsilon-caprolactone) (PCL) chain of mPPCL is included within the channel provided by the CDs to form a columnar, crystalline structure. The PCL/CD ratios determined by H-1 NMR spectroscopy for the ICs with alpha- or gamma-CDs are higher than the stoichiometries because of the steric hindrance of the bulky polyhedral oligomeric silsesquioxane chain end and result in a fraction of the e-caprolactone units free from complexation with the CDs. On the basis of these analyses, we propose some possible structures for these CD/mPPCL ICs. (c) 2006 Wiley Periodicals, Inc.