The influence of side chains on formation of inclusion complexes prepared with polyolefin and cyclodextrins

We investigated the formation of inclusion complexes (ICs) between cyclodextrins (CDs) with different cavity size and polyolefin (PO) with different side chains by using Fourier transform infrared (FTIR) spectroscopy, wide-angle X-ray diffraction (WAXD) and differential scanning calorimetry. The analysis of FTIR spectra revealed that the resultants were complexes of CD and PO, and the analysis of WAXD revealed that the molecules of CD had a channel structure due to the formation of ICs. We found that IC could not be obtained when the cavity size of CD was small for PO molecules to thread and it was too large for cross-sectional area of PO molecules. Thus, it was found that PO1 with few side chains could form IC with α-CD, and PO2 with ethyl side chain could form IC with β-CD and γ-CD, while the PO3 with 2-methyl-propyl side chain could form IC with γ-CD. These results suggest that the cross-sectional areas of polymer and the cavity size of CDs play critical roles in the formation of ICs. It is only possible to form ICs when the polymer chains can tread into cavities of CDs, and the space between the polymer and CD is suitable to provide enough intermolecular interaction to keep the structure of IC stable.