Preparation and characterization of inclusion complexes of two-arm linear and four-arm star-shaped poly(ε-caprolactone)s with α-cyclodextrin

Both four-arm star-shaped poly(epsilon-caprolactone) (4sPCL) and two-arm linear PCL (2LPCL) were synthesized and their inclusion complexation with alpha-cyclodextrin (alpha-CD) were studied. The inclusion complexes (ICs) formed between the PCL polymers and alpha-CD were characterized by H-1-NMR, DSC, TGA, WAXD, and FT-IR, respectively. Both branch arm number and molecular weight of the PCL polymers have apparent effect on the stoichiometry (CL:CD, mol:mol) of these ICs. All these analytical results indicate that the branch arms of the PCL polymers are incorporated into the hydrophobic alpha-CD cavities and their original crystalline properties are completely suppressed. Moreover, the inclusion complexation between two-arm linear or four-arm star-shaped PCL polymers and alpha-CD not only enhances the thermal stability of the guest PCL polymers but also improves that of alpha-CD.