Inclusion Complex Formation between α,γ-Cyclodextrins and a Triblock Copolymer and the Cyclodextrin-Type-Dependent Microphase Structures of Their Coalesced Samples

A triblock copolymer (PCL−PPG−PCL, Mn = 1.38 × 104) of poly(e-caprolactone) (PCL) and poly(propylene glycol) (PPG) was synthesized by ring-opening polymerization of e-caprolactone. Cyclodextrin (CD)-type-dependent formation of inclusion complexes (ICs) between cyclodextrins and this triblock copolymer was studied. Only PCL blocks were included as guests in the IC formed with α-cyclodextrin (α-CD), while both PCL and PPG blocks were included in the IC formed with γ-cyclodextrin (γ-CD). As a result, the copolymer coalesced from its IC crystals with α-CD showed an increased crystallinity, while to the contrary, the copolymer coalesced from its IC crystals with γ-CD exhibited a decreased crystallinity, when both were compared to the as-synthesized triblock copolymer. Fourier transform infrared (FTIR) spectra, 13C CP/MAS solid-state NMR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and wide-angle X-ray diffraction (WAXD) measurements were employed to study the formation of ICs as ...